[Federal Register Volume 62, Number 212 (Monday, November 3, 1997)]
[Proposed Rules]
[Pages 59486-59557]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-28747]



[[Page 59485]]

_______________________________________________________________________

Part III





Environmental Protection Agency





_______________________________________________________________________



40 CFR Parts 141 and 142



National Primary Drinking Water Regulations: Interim Enhanced Surface 
Water Treatment Rule Notice of Data Availability; Proposed Rule

  Federal Register / Vol. 62, No. 212 / Monday November 3, 1997 / 
Proposed Rules  

[[Page 59486]]



ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 141 and 142

[WH-FRL-5915-4]


National Primary Drinking Water Regulations: Interim Enhanced 
Surface Water Treatment Rule Notice of Data Availability

AGENCY: U.S. Environmental Protection Agency (USEPA).

ACTION: Notice of Data Availability; request for comments; reopening of 
comment period.

-----------------------------------------------------------------------

SUMMARY: USEPA proposed in 1994 to amend the Surface Water Treatment 
Rule to provide additional protection against disease-causing organisms 
(pathogens) in drinking water (59 FR 38832: July 29, 1994). This Notice 
of Data Availability summarizes the 1994 proposal; describes new data 
and information that the Agency has obtained and analyses that have 
been developed since the proposal; provides information concerning 
recommendations of the Microbial-Disinfectants/Disinfection Byproducts 
(M-DBP) Advisory Committee (chartered in February 1997 under the 
Federal Advisory Committee Act) on key issues related to the proposal; 
and requests comment on these recommendations as well as on other 
regulatory implications that flow from the new data and information. 
USEPA solicits comment on all aspects of this Notice and the supporting 
record. The Agency also solicits additional data and information that 
may be relevant to the issues discussed in the Notice. USEPA is 
particularly interested in public comment on the Committee's 
recommendations and whether the Agency should reflect these 
recommendations in the final rule. In addition, USEPA is hereby 
providing notice that the Agency is re-opening the comment period for 
the 1994 proposal for 90 days beginning on the date of publication of 
today's Notice in the Federal Register. USEPA also requests that any 
information, data or views submitted to the Agency since the close of 
the comment period on the 1994 proposal that members of the public 
would like the Agency to consider as part of the final rule development 
process be resubmitted during this current 90-day comment period unless 
already in the underlying record in the Docket for this Notice.
    The Interim Enhanced Surface Water Treatment Rule (IESWTR) would 
apply to surface water systems serving 10,000 or more people. USEPA 
intends to promulgate the final rule in November 1998 as required by 
the 1996 Amendments to the Safe Drinking Water Act. The Agency plans 
subsequently to address surface water systems serving fewer than 10,000 
people as part of a ``long-term'' Enhanced Surface Water Treatment Rule 
which may also include additional refinements for larger systems.
    Key issues related to the IESWTR that are addressed in this Notice 
include the establishment of a Maximum Contaminant Level Goal for 
Cryptosporidium; removal of Cryptosporidium by filtration; revised 
turbidity provisions; disinfection benchmark provisions to assure 
continued levels of microbial protection while facilities take the 
necessary steps to comply with new disinfection byproduct standards; 
sanitary surveys; inclusion of Cryptosporidium in the definition of 
ground water under the direct influence of surface water; and inclusion 
of Cryptosporidium in the watershed control requirements for unfiltered 
public water systems. Other issues that are discussed include 
inactivation of Cryptosporidium, viruses and Giardia lamblia; uncovered 
finished water reservoirs; cross connection control; and recycling of 
filter backwash water and filter-to-waste.
    Today's Federal Register also contains a related Notice of Data 
Availability for the Stage 1 Disinfectants/Disinfection Byproducts Rule 
(DBPR). USEPA proposed this rule at the same time as the IESWTR and 
plans to promulgate it along with the IESWTR in November 1998.

DATES: Comments should be postmarked or delivered by hand on or before 
February 3, 1998. Comments must be received or post-marked by midnight 
February 3, 1998.

ADDRESSES: Send written comments to IESWTR NODA Docket Clerk, Water 
Docket (MC-4101); U.S. Environmental Protection Agency; 401 M Street, 
SW; Washington, DC 20460. Please submit an original and three copies of 
your comments and enclosures (including references). If you wish to 
hand-deliver your comments, please call the Docket between 9:00 a.m. 
and 4 p.m., Monday through Friday, excluding legal holidays, to obtain 
the room number for the Docket. Comments may be submitted 
electronically to [email protected].

FOR FURTHER 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 am to 5:30 
pm Eastern Time. For technical inquiries, contact Elizabeth Corr or 
Paul S. Berger, Ph.D.(Microbiology), Office of Ground Water and 
Drinking Water (MC 4607), U.S. Environmental Protection Agency, 401 M 
Street SW, Washington DC 20460; telephone (202) 260-8907 (Corr) or 
(202) 260-3039 (Berger).

Regional Contacts

Region I. Kevin Reilly, Water Supply Section, JFK Federal Bldg., Room 
203, Boston, MA 02203, (617) 565-3616
II. Michael Lowy, Water Supply Section, 290 Broadway, 24th Floor, New 
York, NY 10007-1866, (212) 637-3830
III. Jason Gambatese, Drinking Water Section (3WM41), 841 Chestnut 
Building, Philadelphia, PA 19107, (215) 566-5759
IV. David Parker, Water Supply Section, 345 Courtland Street, Atlanta, 
GA 30365, (404)562-9460
V. Kimberly Harris (micro), Miguel Del Toral (DBP), Water Supply 
Section, 77 W. Jackson Blvd., Chicago, IL 60604, (312) 886-4239 
(Harris), (312) 886-5253 (Del Toral)
VI. Blake L. Atkins, Team Leader, Water Supply Section, 1445 Ross 
Avenue, Dallas, TX 75202, (214) 665-2297
VII. Stan Calow, State Programs Section, 726 Minnesota Ave., Kansas 
City, KS 66101, (913) 551-7410
VIII. Bob Clement, Public Water Supply Section (8WM-DW), 999 18th 
Street, Suite 500, Denver, CO 80202-2466, (303) 312-6653
IX. Bruce Macler, Water Supply Section, 75 Hawthorne Street, San 
Francisco, CA 94105, (415) 744-1884
X. Wendy Marshall, Drinking Water Unit, 1200 Sixth Avenue (OW-136), 
Seattle, WA 98101, (206) 553-1890.

SUPPLEMENTARY INFORMATION:

    Regulated entities. Entities potentially regulated by the IESWTR 
are public water systems that use surface water and serve at least 
10,000 people. Regulated categories and entities include:

------------------------------------------------------------------------
                Category                  Examples of regulated entities
------------------------------------------------------------------------
Public Water System....................  PWSs that use surface water and
                                          serve at least 10,000 people. 
State Governments......................  State government offices that  
                                          regulate drinking water.      
------------------------------------------------------------------------


[[Page 59487]]

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be regulated by the 
IESWTR. This table lists the types of entities that USEPA is now aware 
could potentially be regulated by the rule. Other types of entities not 
listed in this table could also be regulated. To determine whether your 
facility may be regulated by this action, you should carefully examine 
the applicability criteria outlined under Alternatives A and B in 
Sec. 141.70 of the proposed rule (59 FR 38832, July 29, 1994).
    If you have questions regarding the applicability of the IESWTR to 
a particular entity, contact one of the persons listed in the preceding 
FOR FURTHER INFORMATION CONTACT section.
    Additional Information for Commenters. The Agency requests that 
commenters follow the following format: type or print comments in ink, 
and cite, where possible, the paragraph(s) in this Notice to which each 
comment refers. Commenters should use a separate paragraph for each 
method or issue discussed. Electronic comments must be submitted as a 
WP5.1 or WP6.1 file or as an ASCII file avoiding the use of special 
characters and any form of name or title of the Federal Register. 
Comments and data will also be accepted on disks in WordPerfect in 5.1 
or WP6.1 or ASCII file format. Electronic comments on this Notice may 
be filed online at many Federal Depository Libraries. Commenters who 
want EPA to acknowledge receipt of their comments should include a 
self-addressed, stamped envelope. No facsimiles (faxes) will be 
accepted.
    Availability of Record. The record for this Notice, which includes 
supporting documentation as well as printed, paper versions of 
electronic comments, is available for inspection from 9 to 4 p.m., 
Monday through Friday, excluding legal holidays at the Water Docket, 
U.S. EPA Headquarters, 401 M. St., S.W. Washington, D.C. 20460. For 
access to docket materials, please call 202/260-3027 to schedule an 
appointment and obtain the room number.
    Copyright Permission. Supporting documentation reprinted in this 
document from copyrighted material may be reproduced or republished 
without restriction in accordance with 1 CFR 2.6.

List of Abbreviations Used in This Document

ASCE--American Society of Civil Engineers
ASTM--American Society for Testing Materials
AWWA--American Water Works Association
C--the residual concentration of disinfectant, mg/L
CDC--Centers for Disease Control
CFE--Combined Filter Effluent
CFR--Code of Federal Regulations
CPE--Comprehensive Performance Evaluation
CT--the residual concentration of disinfectant multiplied by the 
contact time
DOC--dissolved organic carbon
ESWTR--Enhanced Surface Water Treatment Rule
FACA--Federal Advisory Committee Act
gpm/sf--gallons per minute per square foot
HAA5--Haloacetic acids (monochloroacetic, dichloroacetic, 
trichloroacetic, monobromoacetic, and dibromoacetic acids)
HAV--hepatitis A virus
hrs--hours
ICR--Information Collection Rule
IESWTR--Interim Enhanced Surface Water Treatment Rule
IFA--Individual Filter Assessment
IFE--Individual Filter Effluent
ISO--International Standards Organization
k--the pseudo first-order reaction rate constant
L--liter
Log Inactivation--logarithm of (No/NT)
Log--logarithm (common, base 10)
LTESWTR--Long Term Enhanced Surface Water Treatment Rule
MCL--Maximum Contaminant Level
MCLG--Maximum Contaminant Level Goal
M-DBP--Microbial and Disinfectants/Disinfection Byproducts
mg/L--milligram per liter
mg-min/L--milligram minutes per liter
MMWR--Morbidity and Mortality Weekly Report
mW-s/cm2--milliwatt seconds per square centimeter
No--the initial viable concentration of microorganisms
NPDWR--National Primary Drinking Water Regulation
NT--the concentration of surviving microorganisms at time T
NTU--nephelometric turbidity unit
 deg.C--degrees centigrade
PE--Performance Evaluation
pH--negative logarithm of the effective hydrogen-ion concentration
PV1--poliovirus 1
PV3--poliovirus 3
PWS--Public Water System
RSD--Relative Standard Deviation
SAB--Science Advisory Board
SDWA--Safe Drinking Water Act
T--the contact time, second or minute
TOC--total organic carbon
TTHM--Total Trihalomethanes
TWG--Technical Work Group
UV--ultraviolet
x--log removal Reduction by 1/10**x

Table of Contents

I. Introduction and Background

A. Existing regulations
    1. Surface Water Treatment Rule
    2. Total Trihalomethane MCL
    3. Total Coliform Rule
    4. Information Collection Rule
B. Public health concerns to be addressed
C. Statutory provisions
    1. SDWA and 1986 provisions
    2. Changes to initial provisions and new mandates
D. Regulatory negotiation process
E. Information Collection Rule
F. Formation of 1997 Federal Advisory Committee
G. Overview of 1994 proposed IESWTR
    1. Summary of major elements
    2. Alternative treatment requirements
    3. Possible supplemental treatment requirements
    a. uncovered finished water reservoirs
    b. cross connection control program
    c. State notification of high turbidity levels
    4. Other related issues

II. New Information and Key Issues To Be Addressed

A. MCLG for Cryptosporidium
    1. Summary of 1994 proposal and public comments
    2. New data and perspectives
    3. Advisory Committee recommendations and related issues
B. Removal of Cryptosporidium by filtration
    1. Summary of 1994 proposal and public comments
    2. New data and perspectives
    a. rapid granular filtration
    b. other filtration technologies
    c. multiple barrier approach
    3. Advisory Committee recommendations and related issues
C. Turbidity control
    1. Summary of 1994 proposal as it relates to turbidity issues 
and public comments
    2. New data and perspectives
    a. 95th percentile and maximum turbidity levels of composite 
filtered water
    b. individual filter performance
    c. turbidity measurement
    3. Advisory Committee recommendations and related issues
D. Disinfection benchmark for Stage I DBP MCLs
    1. Applicability
    2. Developing the profile and benchmark
    3. State review
    4. Guidance
    5. Request for public comment
E. Definition of ground water under direct influence of surface 
water (GWUDI)--inclusion of Cryptosporidium in the definition
    1. Summary of 1994 proposal and public comments
    2. Overview of existing guidance
    3. Summary of new data and perspectives

[[Page 59488]]

    4. Request for public comment
F. Inclusion of Cryptosporidium in watershed control requirements
    1. Summary of 1994 proposal and public comments
    2. Overview of existing guidance
    3. Summary of new data and perspectives
G. Sanitary survey requirements
    1. Summary of 1994 proposal
    2. Overview of existing regulations and guidance
    3. New developments
    4. Advisory Committee recommendations and related issues
H. Covered finished water reservoirs
    1. Summary of 1994 proposal and public comments
    2. Overview of existing information
    3. Request for public comment
I. Cross connection control program
    1. Summary of 1994 proposal and public comments
    2. Overview of existing information
    3. Request for public comment
J. Recycling filter backwash water and filtering to waste
    1. Filter backwash recycle configuration
    2. State drinking water regulations
    3. Literature overview of standards of practice
    4. Filter-to-waste
    5. Request for public comment
K. Certification criteria for water plant operators
L. Regulatory compliance schedule and other compliance-related 
issues
    1. Regulatory compliance schedule
    2. Compliance violations and State primacy obligations
    3. Compliance with current regulations
M. Disinfection studies
    1. New Giardia inactivation studies at high pH levels
    2. Effectiveness of different disinfectants on Cryptosporidium
    3. New virus inactivation studies

III. Economic Analysis of M-DBP Advisory Committee Recommendations

A. Overview of RIA for proposed rule
B. What's changed since proposed rule
C. Summary of cost analysis
    1. Total national costs
    2. Household costs
D. Cost of turbidity performance criteria & associated monitoring
    1. System level impact analysis
    2. National impact analysis
    a. decision tree
    b. utility costs
    c. State costs
E. Disinfection benchmark
    1. Decision tree
    2. Utility costs
    3. State costs
F. Sanitary surveys
G. Summary of benefits analysis
IV. National Technology Transfer and Advancement Act

I. Introduction and Background

A. Existing Regulations

1. Surface Water Treatment Rule
    Under the Surface Water Treatment Rule (SWTR)(54 FR 27486, June 29, 
1989), USEPA set maximum contaminant level goals of zero for Giardia 
lamblia, viruses, and Legionella; and promulgated national primary 
drinking water regulations for all public water systems (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) removal or 
inactivation of 3 logs (99.9%) for Giardia and 4 logs (99.99%) for 
viruses; (2) combined filter effluent performance of 5 NTU as a maximum 
and 0.5 NTU at 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 (3) 
watershed protection and other requirements for unfiltered systems.
2. Total Trihalomethane MCL
    USEPA set an interim Maximum Contaminant Level (MCL) for total 
trihalomethanes (TTHM) of 0.10 mg/l as an annual average in November 
1979 (44 FR 68624). This standard was based on the need to balance the 
requirement for continued disinfection of water to reduce exposure to 
pathogenic microorganisms while simultaneously lowering exposure to 
disinfection byproducts which might be carcinogenic to humans.
    The interim TTHM standard only applies to any PWSs (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. About 80 
percent of the PWSs, serving populations of less than 10,000, are 
served by ground water that is generally low in THM precursor content 
(USEPA, 1979) and which would be expected to have low TTHM levels even 
if they disinfect.
3. Total Coliform Rule
    The Total Coliform Rule (54 FR 27544; June 29, 1989), revised in 
June 1989 and effective on December 31, 1990 applies to all public 
water systems (USEPA, 1989b). This regulation sets compliance with the 
Maximum Contaminant Level (MCL) for total coliforms as follows. For 
systems that collect 40 or more samples per month, no more than 5.0% of 
the samples may be total coliform-positive; for those that collect 
fewer than 40 samples, only one sample may be total coliform-positive. 
If a system exceeds the MCL for a month, it must notify the public 
using mandatory language developed by the USEPA. The required 
monitoring frequency for a system ranges from 480 samples per month for 
the largest systems to once annually for certain of the smallest 
systems. All systems must have a written plan identifying where samples 
are to be collected. In addition, systems are required to conduct 
repeat sampling after a positive sample.
    The Total Coliform Rule also requires each system that collects 
fewer than five samples per month to have the system inspected every 5 
years (10 years for certain types of systems using only protected and 
disinfected ground water.) This on-site inspection (referred to as a 
sanitary survey) must be performed by the State or by an agent approved 
by the State.
4. Information Collection Rule
    The Information Collection Rule (ICR) is a monitoring and data 
reporting rule that was promulgated on May 14, 1996 (61 FR 24354) 
(USEPA, 1996b). The purpose of the ICR is to collect occurrence and 
treatment information to evaluate the need for possible changes to the 
current Surface Water Treatment Rule and existing microbial treatment 
practices and to evaluate the need for future regulation for 
disinfectants and DBPs. The ICR will provide USEPA with additional 
information on the national occurrence in drinking water of (1) 
chemical byproducts that form when disinfectants used for microbial 
control react with compounds already present in source water and (2) 
disease-causing microorganisms, including Cryptosporidium, Giardia, and 
viruses. The ICR will also collect engineering data on how PWSs 
currently control such contaminants. This information is being 
collected because the regulatory negotiation on disinfectants and DBPs 
concluded that additional information was needed to assess the 
potential health problem created by the presence of DBPs and pathogens 
in drinking water and to assess the extent and severity of risk in 
order to make sound regulatory and public health decisions. The ICR 
will also provide information to support regulatory impact analyses for 
various regulatory options, and to help develop monitoring strategies 
for cost effectively implementing regulations.

B. Public Health Concerns To Be Addressed

    In 1990, USEPA's Science Advisory Board (SAB), an independent panel 
of experts established by Congress, cited

[[Page 59489]]

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 (USEPA/
SAB 1990). This view was prompted by the SAB's concern about the number 
of waterborne disease outbreaks in the U.S. Between 1980 and 1994, 379 
waterborne disease outbreaks were reported, with over 500,000 cases of 
disease. During this period, a number of agents were implicated as the 
cause, including protozoa, viruses and bacteria, as well as several 
chemicals. Most of the cases (but not outbreaks) were associated with 
surface water, and specifically with a single outbreak of 
cryptosporidiosis in Milwaukee (over 400,000 cases) (Craun, Pers. Comm. 
1997a).
    The number of waterborne disease outbreaks and cases is, however, 
probably much greater than that recorded because the vast majority of 
waterborne disease is probably not reported. Few States have an active 
outbreak surveillance program and disease outbreaks are often not 
recognized in a community or, if recognized, are not traced to the 
drinking water source. This situation is complicated by the fact that 
the vast majority of people experiencing gastrointestinal illness 
(predominantly diarrhea) do not seek medical attention. For those who 
do, physicians generally cannot attribute gastrointestinal illness to 
any specific origin such as a drinking water source. An unknown but 
probably significant portion of waterborne disease is endemic, i.e., 
not associated with an outbreak, and thus is even more difficult to 
recognize.
    One of the key regulations USEPA has developed and implemented to 
counter pathogens in drinking water is the SWTR. Among its provisions, 
the rule requires that a public water system have sufficient treatment 
to reduce the source water concentration of Giardia and viruses by at 
least 99.9% (3 logs) and 99.99% (4 logs), respectively.
    The goal of the SWTR is to reduce risk to less than one infection 
per year per 10,000 people (10-4). However, one of the 
SWTR's shortcomings is that the source waters of some systems have high 
pathogen concentrations that, when reduced by the levels required under 
the rule, still may not meet a common health goal (e.g., 
10-4).
    Another shortcoming of the SWTR is that the rule does not 
specifically control for the protozoan Cryptosporidium. The first 
report of a recognized outbreak caused by Cryptosporidium was published 
during the development of the SWTR (D'Antonio et al., 1985). Other 
outbreaks caused by this pathogen have since been reported both in the 
United States and other countries (Smith et al.,1988; Hayes et al., 
1989; Levine and Craun, 1990; Moore et al., 1993; Craun, 1993). A 
particular public health challenge is that simply increasing existing 
disinfection levels above those most commonly practiced in the United 
States today does not appear to be an effective strategy for 
controlling Cryptosporidium.
    In addition to these issues, there is another potentially counter-
balancing public health concern. The disinfectants used to control 
microbial pathogens may produce toxic or carcinogenic disinfection 
byproducts (DBPs) when they react with organic chemicals in the source 
water. Thus, an important question facing water supply professionals is 
how to minimize the risk from both microbial pathogens and DBPs 
simultaneously.
    At the time the SWTR was promulgated, USEPA had limited data 
concerning Giardia and Cryptosporidium occurrence in source waters and 
treatment efficiencies. The 3-log removal/inactivation of Giardia 
lamblia and 4-log removal/inactivation of enteric viruses required by 
the SWTR were developed to provide protection from most pathogens in 
source waters. However, additional data has become available since 
promulgation of the SWTR concerning source water occurrence and 
treatment efficiencies for Giardia, as well as for Cryptosporidium 
(LeChevallier et al. 1991 a,b). A major concern is that if systems 
currently provide four or more logs of removal/inactivation for 
Giardia, such systems might reduce existing levels of disinfection to 
more easily meet new DBP regulations, and thus only marginally meet the 
three-log removal/inactivation requirement for Giardia lamblia 
specified in the current SWTR. Depending upon source water Giardia 
concentrations, such treatment changes could lead to significant 
increases in microbial risk (Regli et al., 1993; Grubbs et al., 1992; 
USEPA, 1994b).

C. Statutory Provisions

1. SDWA and 1986 Provisions
    The Safe Drinking Water Act (SDWA or the Act), as amended in 1986, 
requires USEPA to publish a ``maximum contaminant level goal'' (MCLG) 
for each contaminant which, in the judgement of the USEPA 
Administrator, ``may have any adverse effect on the health of persons 
and which are 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 also requires that at the same time USEPA publishes an 
MCLG, which is a non-enforceable health goal, it also must publish a 
National Primary Drinking Water Regulation (NPDWR) that specifies 
either a maximum contaminant level (MCL) or treatment technique 
(Sections 1401(1) and 1412(a)(3)). USEPA is authorized to promulgate a 
NPDWR ``that requires the use of a treatment technique in lieu of 
establishing a MCL,'' if the Agency finds that ``it is not economically 
or technologically feasible to ascertain the level of the 
contaminant''.
    Section 1414 (c) of the Act requires each owner or operator of a 
public water system to give notice to the persons served by the system 
of any failure to comply with an MCL or treatment technique requirement 
of, or testing procedure prescribed by, a NPDWR and any failure to 
perform monitoring required by section 1445 of the Act.
    Section 1412(b)(7)(C) of the SDWA requires the USEPA Administrator 
to publish a NPDWR ``specifying criteria under which filtration 
(including coagulation and sedimentation, as appropriate) is required 
as a treatment technique for public water systems supplied by surface 
water sources''. In establishing these criteria, USEPA is required to 
consider ``the quality of source waters, protection afforded by 
watershed management, treatment practices (such as disinfection and 
length of water storage) and other factors relevant to protection of 
health''. This section of the Act also requires USEPA to promulgate a 
NPDWR requiring disinfection as a treatment technique for all public 
water systems and a rule specifying criteria by which variances to this 
requirement may be granted.
2. Changes to Initial Provisions and New Mandates
    In 1996, Congress reauthorized the Safe Drinking Water Act. Several 
of the 1986 provisions discussed above were renumbered and augmented 
with additional language, while other sections mandate new drinking 
water requirements. These modifications, as well as new provisions, are 
detailed below.
    As part of the 1996 amendments to the Safe Drinking Water Act (the 
Amendments), USEPA's general

[[Page 59490]]

authority to set a MCLG and NPDWR was modified to apply 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' (1986 SDWA Section 1412 (b)(3)(A) stricken and 
amended with 1412(b)(1)(A)).
    The Amendments also require that USEPA, when proposing a NPDWR that 
includes an MCL or treatment technique, publish and seek public comment 
on health risk reduction and cost analyses. The Amendments also require 
USEPA 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 1996 Amendments also newly require USEPA to promulgate an 
Interim Enhanced SWTR and a Stage I Disinfectants and Disinfection 
Byproducts Rule by November 1998. In addition, the 1996 Amendments 
require USEPA to promulgate a Final Enhanced SWTR and a Stage 2 
Disinfection Byproducts Rule by November 2000 and May 2002, 
respectively (Section 1412(b)(2)(C)).
    Under the Amendments of 1996, 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 . . .''.

D. Regulatory Negotiation Process

    In 1992 USEPA initiated a negotiated rulemaking to develop a 
disinfectants/disinfection byproducts rule. The negotiators included 
representatives of State and local health and regulatory agencies, 
public water systems, elected officials, consumer groups and 
environmental groups. The Committee met from November 1992 through June 
1993.
    Early in the process, the negotiators agreed that large amounts of 
information necessary to understand how to optimize the use of 
disinfectants to concurrently minimize microbial and DBP risk on a 
plant-specific basis were unavailable. Nevertheless, the Committee 
agreed that USEPA propose a disinfectants/disinfection byproducts rule 
to extend coverage to all community and nontransient noncommunity water 
systems that use disinfectants. This rule proposed to reduce the 
current TTHM MCL, regulate additional disinfection byproducts, set 
limits for the use of disinfectants, and reduce the level of organic 
compounds in the source water that may react with disinfectants to form 
byproducts.
    One of the major goals addressed by the Committee was to develop an 
approach that would reduce the level of exposure from disinfectants and 
DBPs without undermining the control of microbial pathogens. The 
intention was to ensure that drinking water is microbiologically safe 
at the limits set for disinfectants and DBPs and that these chemicals 
do not pose an unacceptable risk at these limits.
    Following months of intensive discussions and technical analysis, 
the Committee recommended the development of three sets of rules: a 
two-staged Disinfectants/Disinfection Byproduct Rule (proposal: 59 FR 
38668, July 29, 1994) (USEPA, 1994a), an ``interim'' ESWTR (proposal: 
59 FR 38832, July 29, 1994) (USEPA, 1994b), and an Information 
Collection rule (proposal: 59 FR 6332, February 10, 1994) (USEPA, 
1994c). The IESWTR would only apply to systems serving 10,000 people or 
more. The Committee agreed that a ``long-term'' ESWTR (LTESWTR) would 
be needed for systems serving fewer than 10,000 people when the results 
of more research and water quality monitoring became available. The 
LTESWTR could also include additional refinements for larger systems.
    The approach in developing these proposals considered the 
constraints of simultaneously treating water to control for both 
microbial contaminants and DBPs. As part of this effort, the 
Negotiating Committee concluded that the SWTR may need to be revised to 
address health risk from high densities of pathogens in poorer quality 
source waters and from the protozoan, Cryptosporidium. The Committee 
also agreed that the schedules for IESWTR and LTESWTR should be 
``linked'' to the schedule for the Stage 1 DBP Rule to assure 
simultaneous compliance and a balanced risk-risk based implementation. 
The Committee agreed that additional information on health risk, 
occurrence, treatment technologies, and analytical methods needed to be 
developed in order to better understand the risk-risk tradeoff, and how 
to accomplish an overall reduction in risk.
    Finally the Negotiating Committee agreed that to develop a 
reasonable set of rules and to understand more fully the limitations of 
the current SWTR, additional field data were critical. Thus, a key 
component of the regulation negotiation agreement was the promulgation 
of the Information Collection Rule (ICR) noted above and described in 
more detail below.

E. Information Collection Rule

    As stated above, the ICR established monitoring and data reporting 
requirements for large public water systems serving populations over 
100,000. About 350 PWSs operating 500 treatment plants are involved in 
the data collection effort. Under the ICR, these PWSs monitor their 
source water for bacteria, viruses, and protozoa (surface water sources 
only); water quality factors affecting DBP formation; and DBPs within 
the treatment plant and in the distribution system. In addition, PWSs 
must provide operating data and a description of their treatment plan 
design. Finally, a subset of PWSs perform treatment studies, using 
either granular activated carbon or membrane processes, to evaluate DBP 
precursor removal. Monitoring for treatment study applicability began 
in September 1996. The remaining occurrence monitoring began in July 
1997.
    The initial intent of the ICR was to collect monitoring data and 
other information for use in developing the Stage 2 DBPR and IESWTR and 
to estimate national costs for various treatment options. However, 
because of delays in promulgating the ICR and technical difficulties 
associated with laboratory approval and review of facility sampling 
plans, most ICR monitoring did not begin until July 1, 1997. As a 
result of this delay and the new Stage 1 DBPR and IESWTR deadlines 
specified in the 1996 SDWA amendments, ICR data will not be available 
for analysis in connection with these rules. In place of the ICR data, 
the Agency has worked with stakeholders to identify additional data 
developed since 1994 that can be used in components of these rules. 
USEPA intends to continue to work with stakeholders in analyzing and 
using the comprehensive ICR data and research for developing subsequent 
revisions to the SWTR and the Stage 2 DBP Rule.

F. Formation of 1997 Federal Advisory Committee

    In May 1996, the Agency initiated a series of public informational 
meetings to exchange information on issues

[[Page 59491]]

related to microbial and disinfectants/disinfection byproducts 
regulations. To help meet the deadlines for the IESWTR and Stage 1 DBPR 
established by Congress in the 1996 SDWA Amendments and to maximize 
stakeholder participation, the Agency established the Microbial and 
Disinfectants/Disinfection Byproducts (M-DBP) Advisory Committee under 
the Federal Advisory Committee Act (FACA) on February 12, 1997, to 
collect, share, and analyze new information and data, as well as to 
build consensus on the regulatory implications of this new information. 
The Committee consists of 17 members representing USEPA, State and 
local public health and regulatory agencies, local elected officials, 
drinking water suppliers, chemical and equipment manufacturers, and 
public interest groups.
    The Committee met five times, in March through July 1997, to 
discuss issues related to the IESWTR and Stage 1 DBPR. Technical 
support for these discussions was provided by a Technical Work Group 
(TWG) established by the Committee at its first meeting in March 1997. 
The Committee's activities resulted in the collection, development, 
evaluation, and presentation of substantial new data and information 
related to key elements of both proposed rules. The Committee reached 
agreement on the following major issues discussed in this Notice and 
the Notice for the Stage 1 DBPR published elsewhere in today's Federal 
Register: (1) MCLs for TTHMs, HAA5 and bromate; (2) requirements for 
enhanced coagulation and enhanced softening (as part of DBP control); 
(3) microbial benchmarking/profiling to provide a methodology and 
process by which a PWS and the State, working together, assure that 
there will be no significant reduction in microbial protection as the 
result of modifying disinfection practices in order to meet MCLs for 
TTHM and HAA5; (4) disinfection credit; (5) turbidity; (6) 
Cryptosporidium MCLG; (7) removal of Cryptosporidium; (8) role of 
Cryptosporidium inactivation as part of a multiple barrier concept and 
(9) sanitary surveys. The Committee's recommendations to USEPA on these 
issues were set forth in an Agreement In Principle document dated July 
15, 1997. This document is included with this notice as Appendix 1.

G. Overview of IESWTR 1994 Proposal

1. Summary of Major Elements
    As part of the IESWTR July 29, 1994, Federal Register notice (59 FR 
38832), USEPA proposed to revise the SWTR to provide additional 
protection against pathogens in drinking water. USEPA proposed to set 
the MCLG for Cryptosporidium at zero based on animal studies and human 
epidemiology studies of waterborne outbreaks of cryptosporidiosis. The 
proposal also focused on treatment requirements for the waterborne 
pathogens Giardia lamblia, Cryptosporidium, Legionella and viruses that 
would apply to all public water systems that use surface water or 
ground water under the influence of surface water and serve 10,000 
people or more. Major features of the proposal included a stricter 
watershed control requirement for systems using surface water that wish 
to avoid filtration; a change in the definition of ground water under 
the influence of surface water to include the presence of 
Cryptosporidium; a periodic sanitary survey requirement for all systems 
using surface water or ground water under the influence of surface 
water; and several alternative requirements, described below, for 
augmenting treatment control of Giardia lamblia, Cryptosporidium, and 
viruses. USEPA also requested comment on several supplemental 
provisions and on other related issues, described below.
2. Alternative Treatment Requirements
    USEPA proposed five treatment alternatives for controlling Giardia 
lamblia, Cryptosporidium, and viruses. Each alternative included 
several options. Alternative A addressed enhanced treatment for Giardia 
lamblia only. Alternatives B and C addressed treatment for 
Cryptosporidium only. Alternative D addressed enhanced treatment for 
viruses only. Alternative E would maintain existing levels of treatment 
for Giardia lamblia and viruses.
    a. Alternative A. Enhanced treatment for Giardia lamblia. The SWTR 
currently requires a 99.9 percent (3-log) removal/inactivation of 
Giardia lamblia for all surface waters, regardless of Giardia lamblia 
cyst concentrations in the source water. Under Alternative A, the 
minimum level of treatment a system would be required to provide (e.g., 
3, 4, 5 or 6 log removal/inactivation) would depend on the Giardia 
lamblia density in the source water as determined by monitoring over 
some specified interval of time. The level of prescribed treatment for 
a particular system would correspond to providing water below an annual 
risk level for Giardia lamblia infections (e.g. 10-4).
    b. Alternative B. Specific Treatment for Cryptosporidium. USEPA 
also proposed a treatment technique for Cryptosporidium similar to the 
proposal for Giardia under Alternative A, such that the required level 
of Cryptosporidium treatment for any particular system would depend on 
the density of Cryptosporidium in the source water.
    c. Alternative C. 99% (2-log) removal of Cryptosporidium. Under 
this alternative, USEPA would require systems to achieve at least a 99% 
(2-log) removal of Cryptosporidium by filtration (with pretreatment). 
The 2-log level was based on the premise that a 3-log level (as 
currently required for Giardia removal/inactivation) is not 
economically or technologically possible, since data suggests that 
Cryptosporidium is consistently more resistant to disinfection than is 
Giardia. USEPA indicated that it would continue to assess new field and 
laboratory data to control Cryptosporidium by physical removal and 
disinfection for consideration in subsequent microbial regulations.
    d. Alternative D. Specific disinfection treatment for viruses. The 
SWTR required systems to achieve a four-log removal/inactivation of 
viruses. This is to be achieved through a combination of filtration and 
disinfection or, for systems not required to filter their source 
waters, by disinfection alone. However, this level of treatment may not 
be adequate to achieve a particular health risk (e.g., 10-4 
infections/yr/person) for viruses. Viruses are of particular concern, 
given that one or several virus particles may be infectious (Regli et 
al.,1991) and that several enteric viruses are associated with 
relatively high mortality rates (Bennett et al., 1987). Failure or 
impairment of filtration performance could allow substantial pathogen 
contamination of drinking water, particularly if the disinfection 
barrier following filtration is minimal.
    Alternative D would require that systems provide sufficient 
disinfection such that disinfection alone would achieve at least a 0.5-
log inactivation of Giardia lamblia or, alternatively, a 4-log 
inactivation of viruses. This proposed approach would be independent of 
the level of physical removal or the source water density of viruses. 
If the filtration process was able to remove three logs of Giardia 
lamblia, a system would still have to provide at least an additional 
0.5-log inactivation of Giardia lamblia or 4-log inactivation of 
viruses by disinfection.
    e. Alternative E. No change to existing SWTR treatment requirements 
for Giardia lamblia and viruses. Alternative E maintains existing SWTR 
levels of

[[Page 59492]]

treatment for Giardia lamblia and viruses. USEPA could regulate 
Cryptosporidium directly (e.g., Alternative C above) or make a finding 
that existing SWTR filtration and disinfection requirements are 
adequate to control this organism.
3. Possible Supplemental Treatment Requirements
    USEPA also requested comment on three supplemental requirements 
regarding uncovered finished water reservoirs, cross connection control 
and State notification of turbidity levels.
    a. Uncovered Finished Water Reservoirs. As part of the 1994 
proposal, USEPA requested comment on possible supplemental requirements 
for uncovered finished water reservoirs. The Agency noted that USEPA 
guidelines recommend that all finished water reservoirs be covered 
(USEPA, 1991a) and that the American Water Works Association (AWWA) 
also has issued a policy statement that strongly supports the covering 
of such reservoirs (AWWA, 1993).
    b. Cross Connection Control Program. USEPA requested comment on 
whether to require States or public water systems to have cross 
connection control programs. Plumbing cross-connections are actual or 
potential connections between a potable and non-potable water supply 
(USEPA, 1989a). According to Craun (1991), 24% of the waterborne 
disease outbreaks that occurred during 1981-1990 were caused by water 
contamination in the distribution system, primarily as the result of 
cross-connections and main repairs.
    c. State Notification of High Turbidity Levels. USEPA also 
requested comment on whether to require systems to notify the State as 
soon as possible for persistent turbidity levels above the performance 
standards or for any other situation that is not now a violation of the 
turbidity standards. Under the SWTR, any time the turbidity of a 
treatment plant's combined filter effluent exceeds 5 NTU the system 
must notify the State as soon as possible, but no later than the end of 
the next business day. In addition, the system must notify the public 
as soon as possible, but in no case later than 14 days after the 
violation.
    USEPA indicated in the proposal that it was considering broadening 
the requirement for State notification. The Agency suggested it might, 
for example, require systems to notify the State as soon as possible if 
at any point during the month it becomes apparent that a system will 
violate the monthly 95th percentile turbidity performance standard 
specified in the SWTR, rather than wait to the end of the month.
    USEPA outlined a number of public health reasons for requiring 
swift State notification for persistent turbidity levels. Pathogens may 
accompany the turbidity particles that exit the filters, especially 
with poor quality source waters. High turbidity levels in the filtered 
water, even for a limited time, may represent a significant risk to the 
public. USEPA's proposed approach was intended to allow States to 
respond in controlling a potentially serious problem more quickly.
    4. Other related issues. The Agency also requested comments on 
other issues related to possible IESWTR options. A number of these are 
listed below.
    (a) To what extent should the ESWTR address the issue of recycling 
filter backwash, given its potential for increasing the densities of 
Giardia lamblia and Cryptosporidium on the filter?
    (b) Should the ESWTR define minimum certification criteria for 
surface water treatment plant operators? Currently the SWTR (40 CFR 
141.70) requires such systems to be operated by ``qualified personnel 
who meet the requirements specified by the State.''
    (c) What criteria, if any, should the ESWTR include to ensure that 
systems optimize treatment plant performance?
    (d) Should turbidity performance criteria be modified? Should 
criteria pertain to individual filters?
    (e) Should the rule include a performance standard for particle 
removal?
    (f) Should the rule include a requirement for an early warning for 
high turbidity?
    (g) Under what conditions could systems be allowed different log 
removal credits than is currently recommended in the SWTR Guidance 
Manual?
    (h) How should USEPA decide, in developing a Notice of Data 
Availability, what treatment approach(es) is most suitable for 
additional public comment?

II. New Information and Key Issues to be Addressed

A. MCLG for Cryptosporidium

1. Summary of 1994 Proposal and Public Comments
    The July 29, 1994, Federal Register notice proposed to set the MCLG 
for Cryptosporidium at zero. The purpose of the MCLG is to protect 
public health. The reasons for this determination were based upon 
animal studies and human epidemiology studies of waterborne outbreaks 
of cryptosporidiosis.
    Most commenters supported an MCLG of zero for Cryptosporidium. 
Those who provided reasons stated that (1) a single cell could infect, 
and data do not support a threshold dose below which an outbreak or 
disease will not occur, (2) the organism is present in water and has 
caused major waterborne disease outbreaks, and (3) it is consistent 
with the goals set under the SWTR and Total Coliform Rule. Commenters 
who opposed the proposed MCLG stated that USEPA needed more health risk 
and organism/disease transmission data and better analytical methods 
before setting an MCLG and regulating Cryptosporidium.
2. New data and Perspectives
    Since publication of the proposed rule, results of a human feeding 
study have become available. Dupont et al. (1995) fed 29 healthy 
volunteers single doses ranging from 30 to 1 million C. parvum oocysts 
obtained from a calf. Of the 16 volunteers who received 300 or more 
oocysts, 88% became infected. Of the five volunteers who received the 
lowest dose (30 oocysts), one became infected. The median infective 
dose was 132 oocysts. According to a mathematical model based upon the 
Dupont et al. data, 0.5% of a population exposed to an average dose of 
one oocyst, would be expected to become infected. (Haas et al., 1996).
    An important concern is that certain populations are at greater 
risk of waterborne disease infection than others. These vulnerable 
populations include the immunocompromised; children, especially the 
very young; the elderly; and pregnant women (Gerba et al. 1996; Fayer 
and Ungar 1986). The most significant segment within these vulnerable 
populations with regard to cryptosporidiosis is people who are 
immunocompromised. In patients with severely weakened immune systems, 
(e.g cancer, AIDS patients), cryptosporidiosis can be serious, long-
lasting and sometimes fatal. There is concern about cryptosporidiosis 
in immunocompromised individuals because currently there is no cure for 
the disease.
    C. parvum is the only Cryptosporidium species known for certain to 
infect humans. One controversial report (the only one of its kind) 
found evidence that C. baileyi, which infects birds, was present in the 
stools and other autopsied organs of an immunodeficient patient 
(Ditrich et al., 1991). There was no indication that Cryptosporidium 
had been responsible in this instance for any adverse health effects. 
C. parvum also infects many other mammals. While C. parvum is a

[[Page 59493]]

well-documented human pathogen, strain variation may occur and one 
strain may cause infection and/or disease at a higher or lower 
concentration than other strains. USEPA is currently funding research 
[Cryptosporidium virulence study using different strains, Herbert 
Dupont] to examine this issue.
    There is some question about the taxonomy (i.e., classification) of 
species within the genus Cryptosporidium. Up until 1980, classification 
was based on the assumption that a particular species only infected one 
type of animal. This assumption appears to be incorrect; hence other 
appropriate taxonomy schemes have been suggested.
    An important issue not directly related to the MCLG involves the 
measurement of C. parvum in water. With current technology, it is often 
very difficult to distinguish between viable and non-viable oocysts. 
When Cryptosporidium is identified it is often not clear whether it is 
C. parvum or another species. Several Cryptosporidium species look 
similar to C. parvum and react to ``specific'' C. parvum stains in a 
like manner (cross-reactions). In addition, it can be difficult to 
distinguish Cryptosporidium from alga and invertebrate eggs (Clancy et 
al. 1994)
    3. Advisory Committee Recommendations and Related Issues
    The M-DBP Federal Advisory Committee supported the proposed 
establishment of a Cryptosporidium MCLG at zero. However, a key issue 
identified by the Committee and public commenters is whether the MCLG 
should be set at the genus level (i.e., Cryptosporidium), as proposed, 
or at the more specific species level (i.e., C. parvum). Setting the 
MCLG at the genus level would automatically include any Cryptosporidium 
species other than C. parvum that is later found to be pathogenic to 
humans. In contrast, setting an MCLG at the species level would 
indicate that only C. parvum infects humans, and would also be 
consistent with the approach taken under the SWTR for Giardia where the 
MCLG is set at the species level (i.e., G. lamblia). USEPA has not 
decided which approach is most appropriate and seeks public comment on 
this issue.
    As indicated above, USEPA's intent in establishing this MCLG at 
zero is to protect public health. The Agency believes there is adequate 
research data to support this determination. However, as noted above, 
the Agency recognizes that there is scientific uncertainty on the issue 
of Cryptosporidium taxonomy and on the question of cross reactions 
between species. USEPA expects further clarification on this issue as 
research continues, Cryptosporidium analytical methods improve, and 
more is learned about the circumstances under which cross-reactivity 
between species occurs. The Agency also wishes to emphasize that the 
scope or specificity of the MCLG may be modified in the future to 
reflect new research and additional information about particular 
species that represent a significant risk to human health.
    As part of this notice, USEPA requests comment on whether to 
establish a Cryptosporidium MCLG at the genus level as proposed or at 
the species level (i.e., Cryptosporidium vs. Cryptosporidium parvum). 
USEPA also requests copies of any additional research, data or other 
information related to this issue.

B. Removal of Cryptosporidium by Filtration

    1. Summary of 1994 Proposal and Public Comments Received
    One of USEPA's proposed treatment Alternatives (Alternative C) 
would require filtered systems to achieve at least a 2 log removal of 
Cryptosporidium oocysts. USEPA recognized that the proposed removal 
level was based on limited data and therefore solicited comment on 
whether other minimum removal levels might be appropriate.
    Most commenters addressing the issue of treatment alternatives 
supported Alternative C. Some commenters opposed any treatment 
requirement greater than a 2 log removal due to a lack of better 
understanding of dose-response, effectiveness of treatment, and 
analyses to justify the higher treatment costs involved.
    Other commenters referred to specific studies (Nieminski 1995; 
Patania et al., 1995) that provided additional information on 
Cryptosporidium removal. One commenter cited a study (Parker and Smith, 
1993), where oocyst damage was observed after agitation with sand. This 
study postulated that oocysts may be damaged as they pass through the 
filtration media. This commenter also pointed to the lack of data on 
cyst removal by full-scale plants and recommended that additional 
research be conducted. Some commenters recognized the need to regulate 
Cryptosporidium, but opposed having the level of treatment based upon 
source water pathogen density (alternative B). One commenter indicated 
that further implementation and evaluation of the adequacy of the SWTR 
needs to occur before modifying it.
2. New Data and Perspectives
    a. Rapid Granular Filtration. Table 1 summarizes research pertinent 
to Cryptosporidium and Giardia lamblia removal efficiencies by rapid 
granular filtration. Brief descriptions of these studies and a summary 
of key points follow.

         Table 1.--Cryptosporidium and Giardia Lamblia Removal Efficiencies by Rapid Granular Filtration        
----------------------------------------------------------------------------------------------------------------
     Type of treatment plant            Log removal      Experimental design              Researcher            
----------------------------------------------------------------------------------------------------------------
Conventional filtration plants...  Crypt 2.7-5.9.......  Pilot Plants.......  Patania et al. 95.                
    Do...........................  Giardia 3.4-5.8.....  ......do...........      Do.                           
    Do...........................  Crypt 2.3-3.0.......  Pilot scale plant..  Nieminski/Ongerth 95.             
    Do...........................  Giardia 3.3-3.4.....  +full scale plant        Do.                           
                                                          with seeded cysts/                                    
                                                          oocysts.                                              
    Do...........................  Crypt 2.7-3.1.......  Pilot Plants.......  Ongerth/Pecaroro 95.              
    Do...........................  Giardia 3.1-3.5.....  ......do...........      Do.                           
    Do...........................  Crypt 2-2.5.........  Full scale plants..  LeChevallier et al. 91b.          
    Do...........................  Giardia 2-2.5.......  Full scale plants..  LeChevallier et al. 91b.          
    Do...........................  Crypt 2.3-2.5.......  Full scale plants..  LeChevallier/Norton 92.           
    Do...........................  Giardia 2.2-2.8.....  ......do...........      Do.                           
    Do...........................  Crypt 2-3...........  Pilot scale plant..  Foundation for Water.             
                                                                              Research 94.                      
    Do...........................  Giardia and.........  Full scale plant...  Kelley et al. 95.                 
    DoCrypt 1.5-2................  operation considered                                                         
                                    ot optimized).                                                              
Direct filtration plants.........  Crypt 1.5-4.0.......  Pilot Plants.......  Patania et al. 1995.              
    Do...........................  Giardia 1.5-4.8.....  ......do...........      Do.                           

[[Page 59494]]

                                                                                                                
    Do...........................  Crypt 2.8-3.0.......  ......do...........  Nieminski/Ongerth 95.             
    Do...........................  Giardia 3.3-3.9.....  ......do...........      Do.                           
    Do...........................  Crypt 2-3...........  ......do...........  West et al. 1994.                 
----------------------------------------------------------------------------------------------------------------

Patania, Nancy L; et al. 1995

    Raw water turbidities were between 0.2 and 13. 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, by up to l log greater than when filter 
effluent turbidities were greater than 0.1 NTU (within the 0.1 to 0.3 
NTU range) (see Figures 1 and 2 below). Cryptosporidium removal rates 
of less than 2.0 log (indicated in Figures 1 and 2) occurred at the end 
of the filtration cycle.
    Blackened data points in these figures represent data in which 
oocysts were not detected in the filtered water. The log removal values 
shown would be greater than indicated had the influent oocyst 
concentration been sufficiently high to show oocyst detection in the 
filtered water. The researchers also noted that removal of 
Cryptosporidium was 0.4 to 0.9 log lower during filter ripening than 
during stable filter operation; Giardia removal was generally 0.4 to 
0.5 log lower during ripening. Cryptosporidium removal was 1.4 to 1.8 
log higher for conventional treatment (including sedimentation) as 
compared to direct filtration. Similarly, Giardia removal was 0.2 to 
1.8 log higher. Figures 1 and 2 below show the log removal rates 
discussed above.
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BILLING CODE 6560-50-C

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

    This study evaluated performance in a pilot plant and in a full 
scale plant (not in operation during the time of the study) and 
considered two treatment modes: direct filtration and conventional 
treatment. The source water of the full scale plant had turbidities 
typically between 2.5 and 11 NTU with a peak level 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 
different source water quality during the filter runs.

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

    This project used very low turbidity source waters (0.35 to 0.58 
NTU). With optimal coagulation, 3 log removal for both cysts were 
obtained. In one test run, where coagulation was intentionally 
suboptimal, the removals were only 1.5 log for Cryptosporidium and 1.3 
log for Giardia. This emphasized 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

    Source water turbidities ranged from less than 1 to 120 NTU. 
Removals of Giardia and Cryptosporidium (2.2-2.8 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 were in varying stages of 
treatment optimization. Removal achieved a median of 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 cysts were 
detected on the finished water below detection protozoan levels were 
set at the detection limit for calculating removal efficiencies.

Foundation for Water Research 1994

    Raw water turbidity ranged from 1 to 30 NTU. Cryptosporidium oocyst 
removal was between 2 and 3 log. Investigators concluded that any 
measure which reduced filter effluent

[[Page 59497]]

turbidity should reduce risk from Cryptosporidium. The importance in 
selecting coagulants, dosages, and pH should not be overlooked. Apart 
from turbidity, indicators of possible reduced efficiency for oocyst 
removal would be increased color and dissolved metal ion coagulant 
concentration in the effluent, for these are indications of reduced 
efficiency of coagulation/ flocculation.

Kelley, M.B. et al. 1995

    Protozoa removal was between 1.5 and 2 log. The authors speculated 
that this low Cryptosporidium removal occurred because the coagulation 
process was not optimized, though the finished water turbidity was less 
than 0.5 NTU. Also, when cysts were not detected in the finished water 
below detection values were assumed as filtered water concentration 
levels.

West, Thomas; et al. 1994

    Pilot scale direct filtration was used with anthracite mono-media 
at filtration rates of 6 and 14 gpm/sq ft. Raw water turbidity was 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, declining 
significantly during particle breakthrough. When effluent turbidity was 
less than 0.1 NTU, removal typically exceeded 2 log. Log removal of 
Cryptosporidium generally exceeded that for particle removal.

Summary of Studies

    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).
    Members of the M-DBP Advisory Committee discussed that tighter 
turbidity performance criteria would increase the likelihood of systems 
achieving higher oocyst removal rates. As a general principle, members 
of the M-DBP Advisory Committee indicated that if a utility were 
required to achieve less than 0.3 NTU 95% of the time, it would target 
substantially lower turbidity levels in order to have confidence that 
it will not exceed the 0.3 level. This principle was also recognized by 
the M-DBP Advisory Committee's Technical Work Group and served as a 
technical basis for much of the Committee's discussion of turbidity 
(i.e., that if the performance standard is 0.3 NTU systems would target 
achieving less than 0.2 NTU 95 percent of the time).
    The Patania and Nieminski/Ongerth studies as they relate to 
finished water turbidity levels and log removal are particularly 
relevant to this point. These particular studies involve finished water 
turbidity at low levels in the same range as the finished water target 
identified by the Committee. The associated removal of Cryptosporidium 
at these turbidity levels was reliably in the range of 2 log or 
greater.
    Other key points discussed during the Advisory Committee's 
deliberations 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 the table tend to be for low-turbidity waters, which are 
considered to be the most difficult to treat regarding particulate 
removal and associated protozoan removal. Since high removal rates have 
been demonstrated in pilot studies using lower-turbidity source waters, 
it is likely that similar or higher removal rates would be achieved for 
higher-turbidity source waters.
     The evaluation of Cryptosporidium removal in full-scale 
plants can be difficult in that this data includes many non-detects in 
the finished water. In these cases, values assigned at the detection 
limit will likely result in over-estimation of oocysts in the finished 
water. This in turn means that removal levels will tend to be under-
estimated.
     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 that still 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;
--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, which is the 
predominant period).
    b. Other Filtration Technologies. Other filtration technologies 
include slow sand and diatomaceous earth filtration. ``Technologies and 
Costs for the Treatment of Microbial Contaminants in Potable Water 
Supplies, October 1988'' by USEPA (1988) listed research studies 
indicating that a well designed and operated plant using these 
technologies is capable of 3-to 4-log removal of Giardia and viruses. 
Recent findings appear in Table 2 below.

                       Table 2.--Cryptosporidium and Giardia Lamblia Removal Efficiencies                       
----------------------------------------------------------------------------------------------------------------
     Type of treatment plant            Log removal      Experimental design              Researcher            
----------------------------------------------------------------------------------------------------------------
Slow Sand........................  Giardia >3..........  Pilot plant at 4.5   Schuller and Ghosh, 91.           
                                                          to.                                                   
                                   Crypt >3............  16.5 degrees C.....                                    
                                   Crypt 4.5...........  Full scale plant...  Timms et al., 1995                
Diatomaceous Earth...............  Giardia >3..........  Pilot plant,         Schuler and Ghosh, 90.            
                                                          addition of.                                          
                                   Crypt >3............  coagulant increased                                    
                                     ..................  removal beyond.....                                    
                                     ..................  values shown.......                                    
----------------------------------------------------------------------------------------------------------------


[[Page 59498]]

    c. Multiple Barrier Approach.
    The M-DBP Advisory Committee engaged in extensive discussion 
regarding the adequacy of relying solely on physical removal to control 
Cryptosporidium in drinking water supplies and on the need for 
inactivation. There was a substantial absence of technical consensus on 
how to or whether it is currently possible to adequately measure 
Cryptosporidium inactivation efficiencies for various disinfection 
technologies. This issue emerged as a significant impediment to 
addressing inactivation in the IESWTR.
    As part of the original 1994 proposal, USEPA included control 
strategies that would entail the development of a map of inactivation 
efficiencies for Cryptosporidium. As discussed later in Section M. of 
this Notice, adequate information to develop such a map is not 
available at this time. The Advisory Committee discussion recognized, 
however, that inactivation requirements may be appropriate and 
necessary under future regulatory scenarios and that physical removal 
by filtration may not be sufficient under all circumstances or for all 
source waters.
    As part of the development process for the long term ESWTR, the 
Advisory Committee recommended that USEPA request comment on a risk-
based proposal for Cryptosporidium embodying the multiple barrier 
approach (e.g., source water protection, physical removal, 
inactivation, etc.), including, where risks suggest appropriate, 
inactivation requirements. In establishing the LTESWTR, the Committee 
recommended that the following issues be evaluated:

--Data and research needs and limitations (e.g., occurrence, treatment, 
viability, active disease surveillance, etc.);
--Technology and methods capabilities and limitations;
--Removal and inactivation effectiveness;
--Risk tradeoffs including risks of significant shifts in disinfection 
practices;
--Cost considerations consistent with the SDWA;
--Reliability and redundancy of systems; and
--Consistency with the requirements of the Act.
3. Advisory Committee Recommendations and Related Issues
    USEPA reiterates its request for comment on the following 
recommendations of the M-DBP Advisory Committee.

    All surface water systems that serve more than 10,000 people and 
are required to filter must achieve at least a 2-log removal of 
Cryptosporidium. Systems which use rapid granular filtration (direct 
filtration or conventional filtration treatment-as currently defined 
in the SWTR), and meet the turbidity requirements described in 
section II.C. are assumed to achieve at least a 2-log removal of 
Cryptosporidium. Systems which use slow sand filtration and 
diatomaceous earth filtration and meet existing turbidity 
performance requirements under the SWTR (less than 1 NTU for the 
95th percentile or alternative criteria as approved by the State) 
are assumed to achieve at least 2-logs removal of Cryptosporidium.
    Systems may demonstrate that they achieve higher levels of 
physical removal.

C. Turbidity Control

1. Summary of 1994 Proposal as it Relates to Turbidity Issues and 
Public Comments
    Finished water turbidity levels are currently regulated by USEPA 
under the SWTR as a treatment technique to ensure removal of Giardia 
and viruses. The SWTR requires systems to monitor the turbidity of the 
combined filter effluent every four hours at each treatment plant. 
Systems using direct filtration or conventional treatment must achieve 
a combined filter effluent turbidity level of no more than 0.5 NTU in 
95% of the measurements in each month and never exceed 5 NTU. Failure 
of individual filters may allow pathogens to enter the distribution 
system. However, the SWTR does not presently require systems to monitor 
the effluent of individual filters.
    As a treatment technique, turbidity is an indicator of filtration 
performance. Treatment plants are, as noted above, required to meet 
certain turbidity levels to meet the removal requirements for Giardia. 
Although turbidity is not a direct indicator of health risk, a very low 
turbidity level of the treated water is in general a good indicator of 
effective Cryptosporidium and Giardia oocyst and cyst removal by rapid 
granular filtration. USEPA continues to believe that turbidity is the 
most readily measurable parameter to indicate filtration treatment 
effectiveness.
    A primary focus of the 1994 proposal was the establishment of 
treatment requirements that would address public health risks from high 
densities of pathogens in poor quality source waters and from the 
waterborne pathogen Cryptosporidium. As discussed earlier in this 
Notice, waterborne pathogens have caused significant disease outbreaks 
in the United States. Approaches outlined in the 1994 proposal included 
treatment requirements based on site-specific concentrations of 
pathogens in source water and a proposed 2-log removal requirement for 
Cryptosporidium by filtration.
    USEPA also specifically requested comment on what criteria, if any, 
should be included to ensure that systems optimize treatment plant 
performance and on whether any of the existing turbidity performance 
criteria should be modified (e.g., should systems be required to base 
compliance with the turbidity standards on individual filter effluent 
monitoring in lieu of or in addition to monitoring the confluence of 
all filters; and should any performance standard value be changed). In 
addition, the Agency requested comment in the 1994 proposal on possible 
supplemental requirements for State notification of persistent high 
turbidity levels (e.g., broadening the requirements for State 
notification of turbidity exceedances).
    Some comments suggested and supported a revised approach to the 
IESWTR that would focus on optimizing existing water treatment 
processes to provide insurance against microbial disease outbreak in 
the absence of source water occurrence data. Another comment suggested 
that current levels of treatment, including filtration, have a 
sufficient degree of effectiveness in preventing transmission of 
Cryptosporidium in drinking water.
    One commenter suggested that turbidity performance standards should 
not be modified until the SWTR has been further implemented. One 
commenter suggested that decreases in turbidity standards or monitoring 
after each filter should be voluntary unless scientific data 
demonstrate otherwise. Another commenter suggested that individual 
filters can be evaluated during sanitary surveys. Several commenters 
supported tighter turbidity standards and monitoring of individual 
filters. Suggested turbidity performance levels included 0.1 or less, 
or 0.2 NTU as revised standards. Several commenters supported 
monitoring of individual filters, with one suggesting backwashing of 
filters when turbidity levels increase.
2. New Data and Perspectives
    As presented in detail below, the M-DBP Advisory Committee's 
recommendations to the Agency included tighter turbidity performance 
criteria and individual filter monitoring requirements as part of the 
IESWTR. These revised performance criteria, along with the individual 
filter monitoring requirements, would better enable systems to 
demonstrate that they meet a 2 log removal requirement for 
Cryptosporidium. Because Cryptosporidium is exceptionally

[[Page 59499]]

resistant to inactivation using chlorine, physical removal by 
filtration is extremely important in controlling this organism. Data 
presented in the previous section of this Notice support modifications 
to the existing turbidity requirements under the SWTR to enable systems 
to demonstrate that they meet the proposed 2 log requirement.
    The revised turbidity performance criteria would also contribute to 
another of the IESWTR's key objectives, which is to establish a 
microbial backstop to prevent significant increases in microbial risk 
when systems implement new disinfection byproduct standards under the 
Stage 1 DBPR. As indicated by data presented below, tighter turbidity 
performance criteria would reflect actual current performance for a 
substantial percentage of systems nationally. Revising the turbidity 
criteria would effectively ensure that these systems continue to 
perform at these levels (in addition to resulting in improved 
performance by systems that currently meet the existing criteria but 
that operate at levels higher than those suggested in the Advisory 
Committee's recommendations). The other major component of a microbial 
backstop would be provisions for disinfection profiling and 
benchmarking, which are discussed in Section D. of this Notice.
    The revisions to the turbidity provisions (including the individual 
filter provisions) recommended by the Committee would also contribute 
to the microbial backstop objective in direct relationship to the 
treatment process itself. The reliability of the disinfection barrier 
as a means for preventing waterborne disease should increase 
substantially as a result of these tighter turbidity provisions 
because:

--There would be fewer and shorter periods of elevated turbidity during 
which the disinfection barrier could be compromised; and
--The removal of particulate matter achieved by the filtration process 
will both be higher on average and more consistent throughout the 
treatment cycle, thus putting less burden on the disinfection barrier.
    a. 95th Percentile and Maximum Turbidity Levels of Composite 
Filtered Water.
    Three data sets, summarizing the historical turbidity performance 
of various filtration plants, were evaluated to assess the national 
impact of modifying existing turbidity requirements. This included 
turbidity information from the American Water Works Service Company 
(AWWSC, 1997), a multi-State data set (which was analyzed in two sets) 
(SAIC, 1997), and information from plants participating in the 
Partnership for Safe Water program (Bissonette, 1997). Only turbidity 
data from plants serving populations greater than 10,000 persons were 
used. The analyses also included only plants that met the current 95th 
percentile turbidity standard, 0.5 NTU, and the current maximum 
turbidity standard, 5 NTU, in all months. Each of the data sets was 
analyzed to assess the current performance of plants with respect to 
the number of months in which selected 95th percentile and maximum 
turbidity levels were exceeded.
    The AWWSC is a privately-held company that owns and operates for 
profit about 70 water treatment facilities located across the country. 
For this analysis, the AWWSC data set (AWWSC, 1997) included one year's 
data for 45 plants in 10 States. The States, with number of plants in 
each state listed in parentheses, are as follows: California (1), 
Connecticut (3), Iowa (2), Indiana (6), Maryland (1), Missouri (2), 
Pennsylvania (24), Tennessee (1), Virginia (2), and West Virginia (3). 
USEPA analyzed the composite filtered effluent turbidity data obtained 
from the AWWSC plants measured every 4-hours.
    The analyses examined two variations of turbidity data obtained 
from the multi-State data set (SAIC, 1997). The multi-State data set 
included 86 plants in 11 states. The States, with number of plants in 
each state listed in parentheses, are as follows: California (10), 
Georgia (5), Kansas (9), New Jersey (5), Ohio (12), Oregon (10), Rhode 
Island (6), Texas (9), Wisconsin (8), West Virginia (6), Wyoming (6). 
The State data was analyzed as two data sets, denoted as State 1 and 
State 2. The State 1 data set included only plant information with 
measurements every 4 hours, comprising slightly more than half of the 
State data (47 plants in CA (10), OR (10), TX (9), WI (6), WY (6), WV 
(6)). The State 2 data set was comprised of both the State 1 data and 
other data including plant information consisting of daily maximum 
turbidity values only, altogether 86 plants.
    The State 1 data set was expected to provide a more accurate 
picture of typical plant performance among the plants in the entire 
State data set because there were more data points per plant. However, 
the State 2 data set increased regional coverage by incorporating data 
from five additional States (GA, KS, NJ, OH, RI) to reflect additional 
geographic variation that may not have been captured in the State 1 
data set.
    In order to determine how many of the systems met lower 95th 
percentile turbidity levels based on turbidity measurements every four 
hours, the data from those States in which systems only report maximum 
daily values had to be statistically adjusted. The adjustment is 
necessary to take into account the difference in the number of reported 
measurements in a month that can exceed a particular level (e.g., 0.3 
NTU) without exceeding the monthly 95th percentile for that level. 
(Systems that report measurements every four hours can have up to 9 of 
180 measurements (5%) that exceed the level in a month; however, there 
is no way to directly calculate an equivalent value for systems that 
only report daily maximum values without making some adjustment.) No 
adjustment was necessary for assessing monthly maximum turbidity 
levels.
    The State 2 analyses adjusted the monthly 95th percentile turbidity 
levels for plants with only daily maximum data. This was done because 
the 95th percentile based on 31 daily turbidity maximums a month will 
overestimate the 95th percentile based on 186 daily measures (or 
measurements every 4 hours). To assess the magnitude of the bias, the 
State 1 data were used to examine the relationship between the 95th 
percentile of the daily maximums and the 95th percentile of the daily 
measurements.
    The State 2 monthly 95th percentile analyses were obtained by 
dividing the estimated monthly 95th percentiles of those systems 
reporting only daily maximums by a factor of 1.2 to account for bias. 
This factor was derived as follows. The daily maximum was determined 
for each day in the State 1 data set and a monthly 95th percentile (of 
the 30 or 31 daily maximums) was determined, i.e., the second largest 
daily maximum. The corresponding monthly 95th percentile based on the 
daily data was also determined. The ratio of these two values was then 
calculated and summarized across months. The median ratio across all 
months was 1.2, with 90 percent of the ratios ranging between 1.0 and 
1.9. The analysis used to derive the adjustment factor examined only 
plants that reported six values per day.
    The remaining data set included in the turbidity analysis was of 
plants participating in the Partnership for Safe Water. The Partnership 
for Safe Water is a joint venture of several organizations, including 
the American Water Works Association, the Association of State Drinking 
Water Administrators, the Association of Metropolitan Water Agencies, 
the National Association of Water Companies, the American Water Works 
Association Research Foundation and USEPA. These organizations

[[Page 59500]]

entered into a voluntary ``partnership'' with the nation's drinking 
water filtration plants treating surface water to tighten treatment 
practices and operational controls to reduce the risk from 
Cryptosporidium and other waterborne pathogens. The Partnership 
approach, described in the ``Partnership for Safe Water Voluntary Water 
Treatment Plant Performance Improvement Program Self-Assessment 
Procedures'' (USEPA et al. 1995), is based on USEPA's Composite 
Correction Program (CCP). The CCP is a voluntary program which is 
described in detail in the handbook Optimizing Water Treatment Plant 
Performance Using the Composite Correction Program--USEPA/625/6-91/027. 
The Partnership for Safe Water utility membership consists of 199 
utilities representing almost 280 water treatment plants. These plants 
serve approximately 80 million persons. The Partnership consists of 
four phases with each phase providing tools and methodologies to assist 
utilities in progressing toward a higher quality finished water. The 
following data summarizes turbidity performance based on 4-hour 
measurements reported by the Partnership utilities for 12 months 
overlapping 1995 and 1996. The data represents a composite of 
Partnership utilities that have completed varying phases of Partnership 
activities, ranging from having just joined to having progressed well 
into the self-assessment phase (phase 3). All data were derived from 
the 1997 Partnership for Safe Water Annual report (Bissonette, 1997).
    The results of the analyses of all of the data sets are shown in 
Tables 3 and 4.
    Tables 3 and 4 indicate the extent to which plants, as currently 
operated, are meeting different turbidity levels. Conversely the data 
indicate the portion of utilities which might need to alter existing 
practice in order to meet lower turbidity limits, if such limits were 
required through regulation.
    Table 3 is organized to reflect the extent to which utilities are 
currently meeting monthly 95th percentile turbidity limits, assuming 
that compliance with such limits is determined as currently done under 
the existing monthly 95th percentile standard of < 0.5 NTU. For 
example, Table 3 indicates that 19.1 percent (based on the Partnership 
data set) and 34.9 percent (based on the State 2 data set) exceed a 
monthly 95th percentile turbidity limit of 0.3 NTU at least one month 
during the year for which data were collected. Table 3 also indicates 
the extent to which utilities meet a particular limit for multiple 
months of the year (i.e., for at least 3 months and for at least 6 
months). The frequency in months by which utilities exceed a particular 
monthly turbidity limit could influence the extent of treatment that 
might be needed to achieve compliance through out the year.
    The Technical Work Group (TWG) which provided technical advice to 
the Advisory Committee made the following recommendations for 
estimating national compliance forecasts.
    (1) The State 2 data set could be used as a reference point for 
estimating potential compliance burdens for systems serving less than 
100,000 people. The Partnership data could be used as a reference point 
for estimating potential compliance burdens for systems serving greater 
than 500,000 people. For systems serving between 100,000 and 500,000 
people, the average of the percentages of systems not meeting a 
particular limit reflected by the Partnership and State 2 data could be 
used for estimating compliance burdens.
    (2) Estimates for systems needing to make changes to meet a 
turbidity performance limit of < 0.3 NTU should be based on the ability 
of systems currently being able to meet a 0.2 NTU as reflected in Table 
3. This assumption would also take into account a utility's concern 
with possible turbidity measurement error.
    For example, for systems serving less than 100,000 people, the TWG 
assumed that 51.7 percent of the systems could be expected to make 
treatment changes to consistently comply with a monthly 95th percentile 
limit of 0.3 NTU. Similarly, for systems serving over 500,000 people, 
the TWG assumed that 41.7 percent could be expected to make treatment 
changes to comply with a 0.3 NTU regulatory limit.
    Table 4 is organized to reflect the extent to which utilities meet 
different monthly maximum turbidity limits (i.e., all measurements 
taken during the month must be below the indicated limit). For example, 
Table 4 indicates that 6 percent of the plants (based on State 2 
Partnership data) are currently exceeding a monthly maximum limit of 
1.0. The data in Table 4 were considered for evaluating possible 
national impacts of lowering the current maximum limit of 5 NTU to some 
lower value.
    Regarding maximum turbidity levels, the Advisory Committee also 
discussed filtered water turbidity levels with respect to the 
cryptosporidiosis outbreak in Milwaukee in 1993. Some members indicated 
concern that filtered water turbidities associated with the outbreak 
apparently were significantly lower than the current maximum turbidity 
level of 5 NTU. Indications are that the turbidity levels were at about 
2 NTU (MacKenzie et al., 1994; Fox and Lytle., 1996).

   Table 3.--Number and Percent of Plants That Exceeded Monthly 95th Percentile Turbidity Limits in at Least N  
                                                Months out of 12                                                
----------------------------------------------------------------------------------------------------------------
                                                  At least 1 month      At least 3 months     At least 6 months 
       Turbidity limit           Data source   -----------------------------------------------------------------
                                                   Num        Pct        Num        Pct        Num        Pct   
----------------------------------------------------------------------------------------------------------------
0.1..........................  State 1........         34       72.3         28       59.6         24       51.1
  State 2                      69.............       80.2         59       68.6         51       59.3           
  AWWSC                        33.............       73.3         24       53.3         15       33.3           
  Partnership                  177............       75.3        136       57.9        100       42.6           
0.2..........................  State 1........         17       36.2          9       19.1          2        4.3
  State 2                      44.............       51.2         29       33.7         15       17.4           
  AWWSC                        12.............       26.7          7       15.6          2        4.4           
  Partnership                  98.............       41.7         51       21.7         27       11.5           
0.3..........................  State 1........         10       21.3          3        6.4          0        0.0
  State 2                      30.............       34.9         11       12.8          3        3.5           
  AWWSC                        6..............       13.3          1        2.4          0        0.0           
  Partnership                  45.............       19.1         17        7.2          7        3.0           
0.4..........................  State 1........          3        6.4          0        0.0          0        0.0
  State 2                      9..............       10.5          1        1.2          0        0.0           
  AWWSC                        3..............        6.7          0        0.0          0        0.0           

[[Page 59501]]

                                                                                                                
  Partnership                  22.............        9.4          5        2.1          3        1.3           
----------------------------------------------------------------------------------------------------------------
Population served 10,000. State 1 (4-hour daily data from 47 plants): 10 CA, 10 OR, 9 TX, 6 WI, 6 WV,
  6 WY. State 2 (86 plants including State 1 data and daily maximums * from additional plants) : 10 CA, 5 GA, 9 
  KS, 5 NJ, 12 OH, 10 OR, 6 RI, 9 TX, 8 WI, 6 WV, 6 WY. AWWSC: 45 plants: 1 CA, 3 CT, 2 IA, 6 IN, 1 MD, 2 MO, 24
  PA, 1 TN, 2 VA, 3 WV. Partnership for Safe Water 235 plants. *For plants with only daily maximums, the monthly
  95th percentile was estimated as the 95th percentile of the daily maximums divided by 1.2. The adjustment was 
  done to account for the potential bias of taking the 95th percentile of daily maximums, and was based on the  
  relationship observed in the State 1 data between the 95th percentile of the daily maximums and the 95th      
  percentile of the 4-hour data.                                                                                


 Table 4.--Number and Percent of Plants That Exceeded Monthly Maximum Turbidity Limits in at Least N Months out 
                                                      of 12                                                     
----------------------------------------------------------------------------------------------------------------
                                                  At least 1 month      At least 3 months     At least 6 months 
   Maximum turbidity limit       Data source   -----------------------------------------------------------------
                                                   Num        Pct        Num        Pct        Num        Pct   
----------------------------------------------------------------------------------------------------------------
0.3..........................  State 1........         36       76.6         15       31.9          6       12.8
  State 2                      69.............       80.2         36       41.9         15        7.4           
  AWWSC                        24.............       53.3         10       22.2          4        8.9           
  Partnership                  129............       54.9         72       30.6         37       15.7           
0.5..........................  State 1........         18       38.3          3        6.4          1        2.1
  State 2                      35.............       40.7          7        8.1          1        1.2           
  AWWSC                        12.............       26.7          3        6.7          0        0.0           
  Partnership                  65.............       27.7         20        8.5          5        2.1           
1.0..........................  State 1........          1        2.1          0        0.0          0        0.0
  State 2                      6..............        7.0          0        0.0          0        0.0           
  AWWSC                        4..............        8.9          0        0.0          0        0.0           
  Partnership                  16.............        6.8          4        1.7          2        0.9           
2.0..........................  State 1........          1        2.1          0        0.0          0        0.0
  State 2                      2..............        2.3          0        0.0          0        0.0           
  AWWSC                        0..............        0.0          0        0.0          0        0.0           
  Partnership                  7..............        3.0          2        0.9          1        0.4           
----------------------------------------------------------------------------------------------------------------

    b. Individual Filter Performance.
    During a turbidity spike, significant amounts of particulate matter 
(including oocysts, if present) may pass through the filter. Figure 3 
presents the turbidity levels over time of a typical filter. The 
greatest potential for a peak (and thus, pathogen break-through) is 
near the beginning of the filter run after filtered backwash or start 
up of operation (Amirtharajah 1988; Bucklin et al. 1988; Cleasby 1990; 
and Hall and Croll 1996).
    Various factors effect 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. The M-DBP Advisory Committee also 
discussed the need to control turbidity spikes in order to limit the 
number of oocysts passing through the filter.

BILLING CODE 6560-50-P

[[Page 59502]]

[GRAPHIC] [TIFF OMITTED] TP03NO97.045



BILLING CODE 6560-50-C
    c. Turbidity Measurement.
    Turbidity is a measure of light scatter that is affected by the 
size distribution and shape of suspended particles in the water. Four 
methods are commonly used to measure turbidity and all are approved for 
use under the SWTR. They include the Nephelometric Method listed in 
2130B of the Standard Methods for the Examination of Water and 
Wastewater, Standard Test Method for Turbidity of Water ASTM (1990) 
D1889-94, the Nephelometric Method in 180.1 of USEPA-600/R-93-100 and 
the Great Lakes Instruments Method 2 (see section 141.74(a)(1)).
    Turbidimeters which measure turbidity commonly consist of the 
following components: (1) a light source and lenses and other optical 
devices to project the light beam at the sample container and to direct 
the scattered light to the detector; (2) a transparent cell that 
contains the water to be measured; (3) light traps within the sample 
chamber that minimize the amount of stray light that reaches the 
detector; and (4) a meter that indicates the intensity of the light 
reaching the detector. While turbidity measurement has long been 
recognized as a means for evaluating treatment performance for removal 
of particulate matter (which include microorganisms), issues remain 
pertinent to the accuracy and precision of the measurement (Hart et al. 
1992; Sethi et al. 1997).
    Large tolerances in instrument design criteria, intended to promote 
competition among instrument manufacturers, have lead to turbidimeters 
with significantly different design features being available on the 
market. Turbidimeters with different designs (but within the design 
specifications of Standard Methods), calibrated according to 
manufacturer's recommendations, have been shown to provide different 
turbidity readings for a given suspension (Hart et al. 1992). The 
significance of this phenomenon as it might pertain to the same water 
with changing turbidities over time or different waters in the U.S. is 
not known. Therefore, narrowing instrument design criteria could reduce 
variation of turbidity measurement but the best direction that such 
change should take is not yet apparent.
    Calibration procedures also affect turbidity measurements. 
Calibration typically involves placing a quantity of a standard 
suspension in the turbidimeter and then adjusting the response so that 
the meter gives a reading equal to the turbidity value assigned to the 
standard. Instruments that are calibrated with currently approved 
different standard suspensions can yield different turbidity 
measurements on the same water (Hart et al. 1992). The significance of 
this phenomenon as it might pertain to the same water with changing 
turbidities over time or different waters in the U.S. is also not 
known. While narrowing specifications for current calibration 
procedures could reduce variation of turbidity measurements, the best 
direction that such change should take is not yet apparent.
    Other factors that may affect turbidity measurement include 
procedures used to prepare and wipe the sample cell and use of sample 
degassing procedures. The extent to which all of the above factors, 
collectively, affect turbidity measurement is not known. However, past 
performance evaluation (PE) studies conducted by USEPA provide some 
indication of accuracy and precision of turbidity measurements among 
different laboratories for a common synthetically prepared water. In PE 
studies, PE samples with known turbidity levels are sent to 
participating laboratories (who are not informed of the turbidity 
level). Laboratories participating in these studies used turbidimeters 
from various manufacturers and conducted their analysis in accordance 
with calibration and analytical procedures they are familiar with. 
Thus, the variability of the results reflect differences resulting from 
using different turbidimeter models and methods and the effects of 
different laboratory procedures. Table 5 summarizes results from PE 
studies conducted at turbidity levels close to the SWTR turbidity 
performance limit of 0.5 NTU. The Relative Standard Deviation (RSD) is 
the Standard Deviation divided by the mean. It appears that the RSD at 
turbidity levels considered in these PE studies are slightly below 20%. 
(A RSD of 20% implies that 95% of one-time turbidity measurements made 
by different laboratories would fall within 40% of the mean. The RSD 
for an individual laboratory, making numerous measurements on a given 
sample water would be expected to be significantly less than that 
achieved among different laboratories (using a variety of turbidimeters 
as indicated in Table 5).

[[Page 59503]]



             Table 5.--USEPA Performance Evaluation Results of Turbidity Measurements (USEPA 1997d)             
                 [Turbidity readings are expressed in NTU, and Relative Standard Deviation in %]                
----------------------------------------------------------------------------------------------------------------
                                                                              No. of                 Relative  S
                          Study No.                            True Turb.    samples        Mean          D     
----------------------------------------------------------------------------------------------------------------
34  USEPA/State.............................................         .720           54         .752         16.0
34  All Lab.................................................         .720         1503         .744         15.8
23  USEPA/State.............................................         .650           24         .659         10.1
25  USEPA/State.............................................         .600           28         .585         13.8
25  All Lab.................................................         .600          708         .597         16.0
25  USEPA/State.............................................         .450           29         .463         20.5
25  All Lab.................................................         .450          707         .481         19.5
22  USEPA/State.............................................         .350           52         .406         16.1
----------------------------------------------------------------------------------------------------------------

    No data is yet available on measurement performance from PE studies 
at levels less than 0.3 NTU. A major concern expressed by participants 
among the Advisory Committee is the ability to reliably measure low 
turbidity levels. The TWG assumed that if systems operated to achieve a 
turbidity limit of less than 0.2 NTU 95 percent of the time, this would 
provide an adequate margin of safety from variability in treatment 
performance and turbidity measurement error, to consistently meet a 
turbidity limit of 0.3 NTU.
    USEPA intends to conduct two PE studies with true turbidities 
ranging from 0.1 to 0.3 NTU. One study is planned to begin no later 
than the end of January 1998 and the other study within 6 months 
thereafter. These new studies will provide an indication of accuracy 
and precision of turbidity measurements at lower levels than previously 
examined. Measurements by on-line turbidimeters will also be evaluated.
    On-line monitoring issues: For expedience, on-line turbidimeters 
are often calibrated against a bench instrument that has been 
accurately calibrated by comparing the turbidity level in a water 
sample. However, at regular intervals they need to be taken off line 
and calibrated, as for bench instruments, by pouring the prepared 
standard suspension into the chamber of the instrument. On-line 
instruments must be inspected regularly to remove air bubbles and 
accumulated debris. Fluctuations in continuous measurements do not 
necessarily signify a decrease in water treatment performance. 
Fluctuations in continuous measurements should be investigated since 
they may be due to air bubbles, debris or a temporary disturbance due 
to a change in the flow rate of sample water flow through the 
turbidimeter. To address the contingency of such phenomenon, the 
Advisory Committee recommended, based on advice from the Technical Work 
Group, that turbidity spikes should be defined on the basis of at least 
2 consecutive measurements taken over some interval of time (e.g., 15 
minutes).
    There is no standard design specification for on-line turbidimeters 
regarding chamber size and recommended flow rate. Thus, turbidity 
spikes of the treated water will be reflected with a delay of a few 
seconds to a few minutes, depending on chamber volume and flow rate of 
the turbidimeter. A turbidity peak measured by a turbidimeter with a 
large chamber volume and small flow rate will result in slightly 
reduced peak.

3. Advisory Committee Recommendations and Related Issues

    USEPA reiterates its request for comment on the following 
recommendations of the M-DBP Advisory Committee.

    1. Turbidity Performance Requirements. For all surface water 
systems that use conventional treatment or direct filtration, serve 
more than 10,000 people, and are required to filter: (a) the 
turbidity level of a system's combined filtered water at each plant 
must be less than or equal to 0.3 NTU in at least 95 percent of the 
measurements taken each month and, (b) the turbidity level of a 
system's combined filtered water at each plant must at no time 
exceed 1 NTU. For both the maximum and the 95th percentile 
requirements, compliance shall be determined based on measurements 
of the combined filter effluent at four-hour intervals.
    2. Individual Filter Requirements. All surface water systems 
that use rapid granular filtration, serve more than 10,000 people, 
and are required to filter shall conduct continuous monitoring of 
turbidity for each individual filter and shall provide an exceptions 
report to the State on a monthly basis. Exceptions reporting shall 
include the following: (1) any individual filter with a turbidity 
level greater than 1.0 NTU based on 2 consecutive measurements 
fifteen minutes apart; and (2) any individual filter with a 
turbidity level greater than 0.5 NTU at the end of the first 4 hours 
of filter operation based on 2 consecutive measurements fifteen 
minutes apart. A filter profile will be produced if no obvious 
reason for the abnormal filter performance can be identified.
    If an individual filter has turbidity levels greater than 1.0 
NTU based on 2 consecutive measurements fifteen minutes apart at any 
time in each of 3 consecutive months, the system shall conduct a 
self-assessment of the filter utilizing as guidance relevant 
portions of guidance issued by the Environmental Protection Agency 
for Comprehensive Performance Evaluation (CPE). If an individual 
filter has turbidity levels greater than 2.0 NTU based on 2 
consecutive measurements fifteen minutes apart at any time in each 
of two consecutive months, the system will arrange for the conduct 
of a CPE by the State or a third party approved by the State.
    3. State Authority: States must have rules or other authority to 
require systems to conduct a Composite Correction Program (CCP) and 
to assure that systems implement any follow-up recommendations that 
result as part of the CCP.

    In reference to the above recommendations, EPA also requests 
comment on what would or would not constitute an obvious reason for 
abnormal filter performance. The Agency also requests comment on how 
much time a system should have to conduct a self-assessment of the 
filter and how much time a system should have to arrange for the 
conduct of a CPE under circumstances such as described in the 
recommendations.
    USEPA also requests comment on whether there are particular filters 
currently in operation in the United States for which specific guidance 
may be needed with regard to individual filter monitoring. For example, 
some members of the M-DBP Advisory Committee suggested that special 
guidance be developed for unique filtration devices made by Infilco 
Degremeont (previously made by Aldridge). These devices consist of 
multi-celled filters with a traveling bridge-automated back washing 
unit that are not conducive to individual cell monitoring.
    USEPA also requests comment regarding existing SWTR provisions for 
lime softening plants that have very low

[[Page 59504]]

turbidity in source waters. The existing SWTR allows States to set 
numerically higher standards up to 1 NTU in 95 percent of samples taken 
per month for conventional treatment and direct filtration plants if 
the State determines that on-site studies demonstrate at least 99.9 
percent overall removal and/or inactivation of Giardia cysts. (54 FR 
27503). In the SWTR (54 FR 27486), the Agency notes that actual 
demonstrations ``(e.g. with pilot plant study results)'' are not 
required for the State to determine when minimum performance 
requirements at the higher turbidity level might be appropriate for a 
particular system. The SWTR states:

    Instead, the State's determination may be based upon an analysis 
of existing design and operating conditions (e.g. adequacy of 
treatment prior to filtration, percent turbidity removal across the 
entire treatment train, stringency of disinfection) and/or 
performance relative to certain water quality characteristics (e.g. 
microbiological analysis of the filtered water, particle size counts 
in water before and after filtration). The State may wish to 
consider such factors as source water quality and system size in 
determining the extent of analysis necessary. (54 FR 27503).

    Committee members raised situations where filtration plants have 
been designed for specific source water quality characteristics such as 
high alkalinity and extremely low turbidity water (e.g. 0.1 to 0.5 
NTU). In systems with such source waters, turbidity levels from the 
filters may actually be higher than in the source waters due to 
reactions from chemicals added mainly for purposes other than source 
water particle removal. Lime softening plants operating under certain 
conditions, depending upon process configuration and raw water 
characteristics or when flocculation conditions change, may 
periodically experience a carry over of extremely fine calcium 
carbonate or magnesium hydroxide particles. These fine particles may 
pass through filters thereby resulting in artificially elevated 
effluent turbidity levels. If turbidity performance criteria are 
tightened under the IESWTR some plants may have difficulty meeting 
these criteria but still achieve substantial removal of Giardia 
lamblia, Cryptosporidium parvum, and viruses. As reflected in the 1989 
SWTR, USEPA believes that in cases where lime softening is practiced 
and source water turbidity levels are low, provisions for alternative 
treatment performance criteria (i.e., in lieu of turbidity) may be 
appropriate.
    As in the present SWTR, USEPA believes that demonstrations of 
equivalent protection need not be based on actual demonstrations (e.g. 
pilot plant study results). Instead the State's determination can be 
based on the factors cited at 54 FR 27503 as quoted above. Other 
factors related to source water microbial quality (e.g. pristine source 
water, source water protection programs, microbial monitoring results, 
bank filtration) may be appropriate for such determinations.
    USEPA requests comment on the appropriateness of continuing 
existing provisions that provide States the flexibility of approving 
higher turbidity levels up to 1 NTU in 95 percent of samples per month 
and up to 2 NTU maximum turbidity for such plants, and additionally 
seeks comments on:

     What types of plants might fall in this category (e.g. 
softening plants designed for color and hardness removal with very 
low turbidity source waters);
     What demonstrations of equivalent protection from 
Giardia lamblia, Cryptosporidium parvum, and viruses are appropriate 
(e.g. microbiological analysis of the filtered water, monitoring 
results for protozoans, watershed control, wellhead protection 
programs);
     What additional or alternative requirements States 
might place on such systems to insure the objective of equivalent 
protection from Giardia lamblia, Cryptosporidium parvum, and viruses 
(e.g. regular monitoring for protozoans in source and or filtered 
water, or for other water quality parameters, watershed control, 
well head protection programs);
     Allowing systems to acidify turbidity samples when 
calcium carbonate carry-over exists to obtain true turbidity 
readings; and
     The appropriateness of including source water microbial 
quality measurements or surrogates as part of a State determination 
of equivalent protection when considering whether to authorize 
higher operating turbidity levels.

D. Disinfection Benchmark for Stage 1 DBP MCLS

    A fundamental principle of the 1992-93 regulatory negotiation which 
was reflected in the 1994 proposal for the IESWTR was that new 
standards for control of byproducts must not result in significant 
increases in microbial risk. This principle was also one of the 
underlying premises of the 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 Stage 1 DBPR. The Advisory Committee's 
recommendations to meet this key objective are discussed in this 
section.
    The approach outlined below represents the recommendation of the 
Advisory Committee to develop a mechanism that is designed to assure 
that pathogen control is maintained while the Stage 1 DBPR provisions 
are implemented. Briefly, the disinfection benchmark addresses the 
three issues of who must gather the necessary information to evaluate 
current practices, how the benchmark operates, and finally, how the 
system and the State work together to assure that microbial control is 
maintained.
    Based on data provided by systems and reviewed by the TWG, the 
baseline of microbial inactivation (expressed as logs of Giardia 
lamblia inactivation) demonstrated high variability. Inactivation 
varied by several logs 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, the TWG developed an approach for a 
system to use to characterize disinfection practice; the procedure is 
called profiling. In essence, this approach allows a plant to chart or 
plot its daily levels of Giardia inactivation on a graph which, when 
viewed on a seasonal or annual basis, represents a ``profile'' of the 
plant's inactivation performance. The system can use the profile to 
develop a baseline or benchmark of inactivation against which to 
measure possible changes in disinfection practice. This approach makes 
it possible for a plant that may need to change practice to meet DBP 
MCLs to assure no significant increase in microbial risk. It provides 
the necessary tool to allow plants to project or measure the possible 
impacts of potential changes in disinfection. Only certain systems 
would be required to develop a profile and keep it on file for State 
review during sanitary surveys, and only a subset of those required to 
develop a profile would be required to submit it to the State as part 
of a package submitted when the system is making significant changes to 
its disinfection practice.
    USEPA reiterates its request for comment on the following 
recommendations of the M-DBP Advisory Committee that address the three 
questions outlined above: (1) who should develop a profile, (2) how a 
profile is actually generated, and (3) how the profile will be used.
1. Applicability
    Systems would be required to prepare a disinfection profile, if at 
least one of the following criteria are met:


[[Page 59505]]


    (1) TTHM levels are at least 80% of the MCL (0.064 mg/l) as an 
annual average for the most recent 12 month compliance period for 
which compliance data are available prior to November 1998 (or some 
other period designated by the State). Monitoring would be in 
accordance with current TTHM requirements.
    (2) Haloacetic acid (HAA5) levels are at least 80% of the MCL 
(0.048 mg/l) as an annual average for the most recent 12 month 
period for which data are available (or some other period designated 
by the State). In connection with HAA5 monitoring, the following 
provisions apply:
    (a) Systems that have collected HAA5 data under the ICR must use 
those data to determine the HAA5 level, unless the State determines 
that there is a more representative annual data set.
    (b) If the system does not have four quarters of HAA5 data by 
the end of 90 days following the IESWTR promulgation date, the PWS 
must conduct HAA5 monitoring for four quarters. This monitoring must 
comply with the monitoring requirements included in the DBP Stage 1 
rule.

    (The Advisory Committee recommended a value of 80% of the MCL 
because available data indicated that DBP levels varied from year to 
year due to many factors (e.g., changes in source water quality, 
changes in water demand). The Committee believed that targeting a level 
20% below the MCL would include most systems that would be expected to 
make changes to comply with the TTHM and HAA5 MCLs on a continuing 
basis. Also, USEPA previously considered this target level at the 
recommendation of the 1992 reg-neg committee, to evaluate DBP Stage 1 
compliance forecasts and costs, based upon the judgement that most 
facilities will take additional steps to ensure continuing MCL 
compliance if they are at or above these levels.)
2. Developing the Profile and Benchmark
    As outlined above, profiling is the characterization of a system's 
disinfection practice over a period of time. The system can create the 
profile by conducting new daily monitoring or by using 
``grandfathered'' data (as explained below). A disinfection profile 
consists of a compilation of daily Giardia lamblia log inactivations 
(or virus inactivations under conditions to be specified in the final 
rule), computed over the period of a year, based on daily measurements 
of operational data (disinfectant residual concentration(s), contact 
time(s), temperature(s), and where necessary, pH(s)).
    Grandfathered data are those operational data that a system 
previously collected at a treatment plant during the course of normal 
operation. These data may or may not have been used previously for 
compliance determinations with the SWTR. Those systems that have all 
necessary data to determine profiles, using operational data collected 
prior to promulgation of the IESWTR, would be able to use up to three 
years of operational data in developing profiles. Grandfathered 
operational data should be substantially equivalent to operational data 
that would be collected under this rule.
    Those systems that do not have three years of operational data to 
develop profiles would have to conduct monitoring to develop the 
profile for one year beginning no later than 15 months after IESWTR 
promulgation. If the PWS has existing operational data to develop 
profiles, it would have to use those data to develop profiles for the 
years prior to the IESWTR promulgation.
    In order to develop the profile, a system would have to:

--Measure disinfectant residual concentration (C, in mg/l) prior to 
entrance into distribution system and just prior to each additional 
point of disinfectant addition, whether with the same or a different 
disinfectant.
--Determine contact time (T, in minutes) during peak flow conditions. T 
can be based on either a tracer study or assumptions based on contactor 
geometry and baffling. However, systems would have to use the same 
method for both grandfathered data and new data.
--Measure water temperature ( deg. C).
--Measure pH (for chlorine only).
    The system would then have to convert operational data to log 
inactivation values for Giardia (and viruses when chloramines or ozone 
used as primary disinfectant).

--Determine CTactual for each disinfection segment.
--Determine CT99.9 (i.e., 3-logs inactivation) from tables 
in the SWTR/IESWTR using temperature (and pH for chlorine) for each 
disinfection segment. [NOTE: USEPA may redesign the tables so that no 
conversion is necessary (i.e., the tables will reflect a 
CT90 (1-log) value.]
--For each segment, log inactivation = (CTact/
CT99.9)  x  3.0.
    A log inactivation benchmark would then be calculated as follows:
    1. Calculate the average log inactivation for each calendar month.
    2. Determine the calendar month with the lowest average log 
inactivation.
    3. The lowest average month becomes the critical period for that 
year.
    4. If 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 for 
that year is the benchmark.
3. State Review
    The State would review disinfection profiles as part of its 
periodic sanitary survey. If a system that is required to develop a 
disinfection profile subsequently decides to make a significant change 
in disinfection practice, it would have to consult with the State 
before implementing such a change. Significant changes would be defined 
as: (1) moving the point of disinfection, (2) changing the type of 
disinfectant, (3) changing the disinfection process, or (4) making any 
other change designated as significant by the State. Supporting 
materials for such consultation would have to include a description of 
the proposed change, the disinfection profile, and an analysis of how 
the proposed change will affect the current disinfection benchmark.
4. Guidance
    USEPA, in consultation with interested stakeholders, will develop 
guidance for States and systems on how to develop and evaluate 
disinfection profiles, how to identify and evaluate significant changes 
in disinfection practices, and guidance on moving the point of 
disinfection from before the point of coagulant addition to after the 
point of coagulant addition. USEPA will also develop guidance for 
systems that would be required to develop a profile based on virus 
inactivation instead of Giardia lamblia inactivation. Guidance will be 
available when the IESWTR is promulgated.
5. Request for Public Comment
    USEPA requests comment on all aspects of the recommendation 
outlined above and any alternative suggestions that stakeholders or 
other interested parties may have. Commenters may want to focus 
particular attention on the following issues:

--Applicability requirements,
--Characterization of disinfection practices and components (e.g., 
monitoring, analysis),
--Use of TTHM and HAA5 data from the same time period instead of TTHM 
data from one year and HAA5 data from another,
--Definition of significant changes to disinfection practice,
--Different approaches to evaluating possible changes in disinfection 
practice against a disinfection profile, and
--Whether the use of grandfathered data, if available, should be

[[Page 59506]]

mandatory for profiling and benchmarking.

E. Definition of Ground Water Under the Direct Influence of Surface 
Water (GWUDI)--Inclusion of Cryptosporidium in the Definition

1. Summary of 1994 Proposal and Public Comments
    The July 29, 1994, Federal Register notice proposed to amend the 
SWTR by including Cryptosporidium in the definition of a GWUDI system. 
Under the rule, a system using ground water considered vulnerable to 
Cryptosporidium contamination would be subject to the provisions of the 
SWTR. USEPA proposed that this determination be made by the State for 
individual sources using State-established criteria.
    The 1994 proposed IESWTR also requested comment on revisions to 
USEPA's guidance on this issue. Cryptosporidium oocysts are smaller 
than Giardia cysts and may have substantially different hydrodynamic 
behavior in ground water due to their smaller size and perhaps also due 
to a difference in charge distribution on the outer surface of the 
oocyst. USEPA guidance for the determination of GWUDI suggests methods 
that may be insensitive to this differing hydrodynamic behavior in 
ground water.
    Almost all commenters agreed that Cryptosporidium should be added 
to the definition. Only one commenter clearly opposed the addition 
without caveat, maintaining that problems with the analytical methods 
for the recovery and enumeration of viable organisms and uncertainties 
associated with risk assessment should preclude its addition. One 
commenter contended that Cryptosporidium should be included only if 
USEPA addresses the amount of natural disinfection at each site and 
defines treatment effectiveness, especially coagulant use, for GWUDI 
systems. One commenter believed that the definition of Cryptosporidium 
should be made at the species level, e.g. Cryptosporidium parvum, 
because other species were not pathogenic to humans.
    One commenter was concerned about the Microscopic Particulate 
Analysis (MPA), one of the methods that USEPA identifies in guidance as 
being suitable for making GWUDI determinations. As part of this method, 
a microscopic examination is made of the ground water to determine 
whether insect parts, plant debris, rotifers, nematodes, Giardia 
lamblia, and other material associated with the surface or near surface 
environment are present. The commenter claimed that the MPA has 
analytical method problems similar to those associated with the 
recovery of cysts and oocysts from environmental samples and suggested 
that the method should undergo additional testing with positive and 
negative controls and with performance evaluation samples.
2. Overview of Existing Guidance
    USEPA issued guidance on the MPA in October 1992 as the Consensus 
Method for Determining Groundwater Under the Direct Influence of 
Surface Water Using Microscopic Particulate Analysis. Additional 
guidance for making GWUDI determinations is also available (USEPA, 
1994e,f). 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 USEPA and the Association of State Drinking Water 
Administrators. AWWARF has also published guidance (Wilson et al., 
1996).
3. Summary of New Data and Perspectives
    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.
    USEPA is interested in an expanded discussion of MPA performance. 
The work cited here is preliminary information and represents the only 
data provided to USEPA so far. USEPA is considering several analytical 
activities to address possible changes in the GWUDI determination 
guidance. These changes are as follows:
     Change the MPA methodology to include a score for 
Cryptosporidium oocysts in the risk rating method.
     Conduct additional comparison of MPA scores with cyst and 
oocyst recovery to evaluate the performance of MPA as an indicator 
method (e.g., Schulmeyer, 1995).
     Conduct additional MPA performance evaluation testing 
(with both positive and negative controls).
     Compare MPA scores and cyst/oocyst recovery in horizontal 
collector wells and vertical wells to determine if additional guidance 
for horizontal collector wells is needed.
4. Request for Public Comment
    USEPA is continuing to consider inclusion of Cryptosporidium in the 
definition of GWUDI. USEPA requests further comment on this issue as 
well as on issues outlined above pertaining to guidance for GWUDI 
determinations.

F. Inclusion of Cryptosporidium in Watershed Control Requirements

1. Summary of 1994 Proposal and Public Comments
    USEPA proposed to extend the existing watershed control 
requirements for unfiltered systems to include the control of 
Cryptosporidium. This would be analogous to and build upon the existing 
requirements for Giardia lamblia and viruses; Cryptosporidium would be 
included in the watershed control provisions wherever Giardia lamblia 
is mentioned. USEPA also proposed requiring a State, as a condition of 
primacy, to describe how it would judge the adequacy of watershed 
control programs for Cryptosporidium as well as Giardia lamblia and 
viruses in the source water.
    Several commenters to the proposed rule specifically supported 
inclusion of Cryptosporidium in watershed control. Others supported 
watershed control programs in general without specifically articulating 
an opinion on Cryptosporidium. One commenter specifically opposed the 
inclusion of Cryptosporidium in watershed control program, maintaining 
that other avenues of watershed control could be promoted without 
including this organism in the control plan. Another commenter opposed 
including Cryptosporidium because environmental sources of Giardia and 
Cryptosporidium were not sufficiently understood. This commenter also 
opposed the requirement to include Cryptosporidium

[[Page 59507]]

in State watershed control program protocols as a condition of primacy.
    Other comments included: (1) Systems need to be informed of the 
nature of upstream pathogen sources and changes in upstream water 
quality in a timely manner, (2) watershed characteristics should not be 
the sole basis for determining water treatment strategies, (3) upstream 
sewage discharges should be prohibited and cattle farming and feedlots 
prohibited or substantially limited in a watershed, and (4) watershed 
control programs should be scientifically based, educational, and 
voluntary. One commenter contended that the burden of contamination on 
the watershed should not fall to the drinking water systems, and that 
better coordination on regulations is needed between the USEPA's 
drinking water and wastewater programs.
2. Overview of Existing Guidance
    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 minimize the 
potential for source water contamination by Giardia lamblia and 
viruses. This program must include a characterization of the watershed 
hydrology characteristics, land ownership and activities which may have 
an adverse effect on source water quality. The SWTR Guidance Manual 
(USEPA, 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 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.
3. Summary of New Data and Perspectives
    Since proposal of the IESWTR in July 1994, several new outbreaks of 
waterborne cryptosporidiosis have occurred in the United States. A 
recent summary of these outbreaks (Solo-Gabriele and Neumeister, 1996) 
identified raw sewage, surface runoff from livestock grazing areas, 
septic tank effluent, cattle wastes, treated wastewater, and backflow 
of contaminated water in the distribution system as the suspected 
sources of Cryptosporidium contamination of the water supplies in these 
outbreaks. Cattle grazing, feedstocks and in particular, calves and 
other young livestock, appear to be of greater concern for 
Cryptosporidium contamination than for Giardia. Some outbreaks of 
cryptosporidiosis have been related to upsets in the treatment process 
of filtered water systems or have occurred on occasions when spikes in 
turbidity have occurred in those systems. However, little information 
is available for unfiltered water systems as to whether spikes in raw 
water turbidity increase the likelihood that elevated levels of 
Cryptosporidium are present in the source water. Because 
Cryptosporidium cannot easily be controlled with conventional 
disinfection practices, there is particular concern about the presence 
of this organism in the source waters of systems that do not filter.
    Data from the ICR may be useful in providing information on the 
relative Giardia and Cryptosporidium levels in the raw water sources of 
unfiltered and filtered water systems. In one comprehensive study on 
Giardia and Cryptosporidium densities in ambient water and drinking 
water, investigators (LeChevallier and Norton, 1995) found 
Cryptosporidium oocyst levels in ambient water ranging from 0.065/L to 
65.1/L, with a geometric mean of 2.4 oocysts/L. In drinking water, the 
level of Cryptosporidium oocysts ranged from 0.29-57 oocysts/100L, with 
a mean of 3.3 oocysts/100L.
    The Seattle Water Department summarized the Giardia and 
Cryptosporidium monitoring results from several unfiltered water 
systems (Montgomery Watson, 1995). The central tendency of this data is 
about 1 oocyst/100L. Thus, depending upon what removal efficiencies are 
achieved by filtration for Cryptosporidium (for example, 2 logs), it 
appears that unfiltered water systems that comply with the source water 
requirements of the SWTR may have a risk of cryptosporidiosis 
equivalent to that of a water system with a well-operated filter plant 
using a water source of average quality.
    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. 
USEPA is considering adding specific monitoring requirements to the 
IESWTR for the unfiltered supplies serving 10,000 or more people to 
ensure the continued effectiveness of the watershed control program. 
The monitoring would be similar to the requirements under the ICR for 
Giardia and Cryptosporidium although the sampling frequency may be 
modified. As with the ICR, a USEPA-approved method and laboratory for 
Giardia and Cryptosporidium analyses would be required.
    At a minimum, such a monitoring program might require some level of 
routine sampling (e.g., on a weekly, biweekly or monthly basis). The 
program may also include ``event'' sampling. An ``event'' would 
constitute an occasion when the raw water turbidity and/or fecal/total 
coliform concentration exceeded a specific value or possibly exceeded a 
site-specific 90th percentile value. At least one sample during an 
event might be required in addition to routine sampling. Results of all 
protozoa and related analyses would be made available to the State at a 
minimum as part of the annual on-site inspection required under the 
SWTR for non-filtering supplies.
    USEPA is continuing to consider extending the existing watershed 
control requirements for unfiltered systems to include the control of 
Cryptosporidium. USEPA requests further comment on this issue. The 
Agency also requests comment on issues pertaining to monitoring for 
unfiltered systems serving 10,000 or more people, including comment on 
the following approaches:
    Routine Source Water Giardia and Cryptosporidium Monitoring:

Option 1. Weekly Giardia and Cryptosporidium Monitoring
Option 2. Bi-Weekly Giardia and Cryptosporidium Monitoring
Option 3. Monthly Giardia and Cryptosporidium Monitoring

The Agency also requests comments on whether the frequency of 
monitoring should depend on system size, e.g., should requirements 
differ for systems serving between 10-100,000 people versus those 
serving more than 100,000 people.
    ``Event'' Source Water Giardia and Cryptosporidium Monitoring:

    Option 1. No event sampling required.
    Option 2. Collect sample(s) for Giardia and Cryptosporidium when 
source water turbidity exceeds 1.0 NTU or some alternative value such 
as a site-

[[Page 59508]]

specific 90th percentile which might be lower than 1.0 NTU.
    Option 3. Collect sample(s) for Giardia and Cryptosporidium when 
source water fecal coliform concentration exceeds 20 per 100 mL or 
total coliform level exceeds 100 per 100 mL, depending on which class 
of coliforms is used under the individual systems filtration avoidance 
agreement. Alternatively, the trigger could be some other coliform or 
fecal coliform value.
    Option 4. Individual utility develops turbidity frequency 
distribution (e.g., based on previous 1 to 3 years of daily historical 
data) and collects sample(s) for Giardia and Cryptosporidium when 
turbidity exceeds 90th percentile level.
    Option 5. Some combination of Options 2, 3, or 4.
    The Agency also requests comment on whether any of the above 
options should depend on system size.

G. Sanitary Survey Requirements

    1. Summary of 1994 Proposal and Public Comments
    The July 29, 1994, Federal Register proposed to amend the SWTR to 
require periodic sanitary surveys for all public water systems that use 
surface water, or ground water under the direct influence of surface 
water, regardless of whether they filter or not. States would be 
required to review the results of each sanitary survey to determine 
whether the existing monitoring and treatment practices for that system 
are adequate, and if not, what corrective measures are needed to 
provide adequate drinking water quality.
    The July 1994 notice proposed that only the State or an agent 
approved by the State would be able to conduct the required sanitary 
survey, except in the unusual case where a State has not yet 
implemented this requirement, i.e., the State had neither performed the 
required sanitary survey nor generated a list of approved agents. The 
proposal suggested that under exceptional circumstances the sanitary 
survey could be conducted by the public water system with a report 
submitted to the State within 90 days. USEPA also requested comment on 
whether sanitary surveys should be required every three or every five 
years.
    Most commenters on this issue voiced support for requiring a 
periodic sanitary survey for all systems. One commenter suggested that 
USEPA develop sanitary survey guidance for administration by the 
States, while another commenter suggested that sanitary surveys by the 
private sector be certified by States or national associations using 
USEPA-defined criteria. Commenters recommended that surveys be 
conducted either by the State or a private independent party/
contractor. One respondent contended that sanitary surveys, as 
presently conducted, were insufficient to assess operational 
effectiveness in surface water systems.
    With regard to sanitary survey frequency, commenters were nearly 
evenly divided between every three years and every five years. Some 
commenters argued that the frequency should depend on: (1) whether a 
system's control is effective or marginal, (2) system size (less 
frequent for small systems), (3) source water quality, (4) whether the 
State believes a system's water quality is likely to change over time, 
(5) results of the previous survey, and (6) population density on the 
watershed. One commenter suggested an annual sanitary survey.
    Regarding criteria for sanitary survey inspectors, some commenters 
suggested that the State should decide what requirements to use. Others 
suggested some combination of education and working experience related 
to water plant operations, including (1) professional engineering 
certificate and water plant operator license for at least five years, 
(2) knowledge of surface water contaminants, source and fate of 
contaminants, and both removal capabilities of existing treatment 
technologies and ability to evaluate their performance, (3) a BS degree 
(preferably MS degree) in sanitary or environmental engineering with 
two years experience in evaluating water treatment plants and valid 
plant operator's license, (4) five years experience in water system 
operation, evaluation, and/or design, and a BS in engineering or 
environmental science, (5) a BS degree in science or engineering and 
five years experience in the drinking water field.
2. Overview of Existing Regulations and Guidance
    Sanitary surveys have historically been conducted by state drinking 
water programs as a preventive tool to identify water system 
deficiencies that could pose a threat to public health. The first 
regulatory requirement for systems to have a periodic on-site sanitary 
survey appeared in the final TCR (54 FR 27544-27568). This rule 
requires all systems that collect less than 5 total coliform samples 
each month to undergo such surveys. These sanitary surveys must be 
conducted by the State or an agent approved by the State. Community 
water systems were to have had the first sanitary survey conducted by 
June 29, 1994, and every five years thereafter while non-community 
water systems are to have the first sanitary survey conducted by June 
29, 1999, and every five years thereafter unless the system is served 
by a protected and disinfected ground water supply, in which case, a 
survey must be conducted every 10 years.
    The SWTR did not specifically require water systems to undergo a 
sanitary survey. Instead, it required that unfiltered water systems, as 
one criterion to remain unfiltered, have an annual on-site inspection 
to assess the system's watershed control program and disinfection 
treatment process. The on-site survey must be conducted by the State or 
a party approved by the state. This on-site survey is not a substitute 
for a more comprehensive sanitary survey, but the information can be 
used to supplement a full sanitary survey.
    USEPA's SWTR Guidance Manual (USEPA, 1991a), Appendix K, suggests 
that, in addition to the annual on-site inspection, a sanitary survey 
be conducted every three to five years by both filtered and unfiltered 
systems. This time period is suggested ``since the time and effort 
needed to conduct the comprehensive survey makes it impractical for it 
to be conducted annually.''
3. New Developments
    Since the publication of the proposed ESWTR in 1994, USEPA and the 
States (through the Association of State Drinking Water Authorities) 
have issued a joint guidance on sanitary surveys entitled USEPA/State 
Joint Guidance on Sanitary Surveys (1995). The Guidance outlines the 
following elements as integral components of a comprehensive sanitary 
survey:

 Source
    --Protection
    --Physical Components and Condition
 Treatment
 Distribution System
 Finished Water Storage
 Pumps/Pump Facilities and Controls
 Monitoring/Reporting/Data Verification
 Water System Management/Operations
 Operator Compliance with State Requirements

    The guidance also addresses the qualifications for sanitary survey 
inspectors, the development of assessment criteria, documentation, 
follow-up after the survey, tracking and enforcement.
    USEPA is aware that a number of States have independently developed 
their own sanitary survey criteria. For instance, the American Water 
Works Association California-Nevada Section,

[[Page 59509]]

Source Water Quality Committee in conjunction with the California 
Department of Health Services, Division of Drinking Water and 
Environmental Management (DHS) have published a document entitled 
Watershed Sanitary Survey Guidance Manual (AWWA California -Nevada 
Section 1993) to assist domestic water suppliers in defining the scope 
of their watershed sanitary surveys and to provide information on the 
methods and sources of information for conducting sanitary surveys.
4. Advisory Committee Recommendations and Related Issues
    USEPA reiterates its request for comment on the following 
recommendations of the M-DBP Advisory Committee.

    A sanitary survey would be defined as an onsite review of the 
water source (identifying sources of contamination using results of 
source water assessments where available), facilities, equipment, 
operation, maintenance, and monitoring compliance of a system to 
evaluate the adequacy of the system, its sources and operations and 
the distribution of safe drinking water. Included in this definition 
is the concept that components of a sanitary survey may be completed 
as part of a staged or phased State review process within the 
established frequency interval set forth below. Finally, for a 
sanitary survey to fall within this definition, it must address each 
of the eight elements in the December 1995 USEPA/State Guidance on 
Sanitary Surveys.
    In terms of frequency, this approach would provide that sanitary 
surveys must be conducted for all surface water systems (including 
ground water under the influence) no less frequently than every 
three years for community systems and no less frequently than every 
five years for noncommunity systems. Any sanitary survey conducted 
after December 1995, that addresses the eight sanitary survey 
components of the 1995 EPA/State guidance, may be counted or 
``grandfathered'' for purposes of completing the round of surveys. 
This approach would also provide that for community systems 
determined by the State to have outstanding performance based on 
prior sanitary surveys, successive sanitary surveys may be conducted 
no less than every five years.
    Finally, under this approach, as part of follow-up activity for 
sanitary surveys, systems must respond to deficiencies outlined in 
the State's sanitary survey report within 45 days, indicating how 
and on what schedule the system will address significant 
deficiencies noted in the survey. In addition, States must have the 
appropriate rules or other authority to assure that facilities take 
the steps necessary to address significant deficiencies identified 
in the survey report that are within the control of the PWS and its 
governing body.

    USEPA also requests comment on whether systems should be required 
to respond in writing to a State's sanitary survey report discussed in 
the paragraph above. USEPA also requests comment on (1) what would 
constitute ``outstanding performance'' for purposes of allowing 
sanitary surveys for a community water system to be conducted every 
five years and (2) how to define ``significant deficiencies.''

H. Covered Finished Water Reservoirs

1. Summary of the 1994 Proposal and Public Comments Received
    The July 29, 1994, Federal Register indicated that USEPA was 
considering whether to issue regulations requiring systems to cover 
finished water reservoirs and storage tanks, and requested public 
comment. The rationale for this position was given in the proposed 
rule.
    Most commenters supported either federal or State requirements. 
Some commenters suggested that regulations apply only to new 
reservoirs. Some commenters opposed any requirement, citing high cost, 
the notion that ``one size does not fit all'', and aesthetic benefits 
of an open reservoir.
    Some commenters suggested elements for such regulations or 
guidance, including (1) applying the same criteria to finished water 
reservoirs as exists for unfiltered surface water systems, (2) using 
engineering measures to minimize contamination, (3) disinfecting the 
effluent to maintain residual in distribution system, (4) monitoring 
reservoirs routinely for water quality indicators, (5) covering all 
storage tanks, (6) fencing reservoirs with signs warning against 
swimming, trespassing, and tampering, and (7) adding notices in the 
annual water quality report that the reservoir is not in compliance 
with current waterworks standards. A few commenters suggested a number 
of other elements.
2. Overview of Existing Information
    Possible Health Concerns: 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. It may be 
subject to contamination by persons tossing items into the reservoir or 
illegal swimming (Pluntze 1974; Erb, 1989).
    Microscopic and other organisms may proliferate in open finished 
water reservoirs. 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., 1996; Geldreich, 1990; Fayer and Ungar, 1986; Current, 
1986). Mammals, birds and fish and their carcasses seed the water and 
the sediment with total and fecal coliforms, E. coli and pathogens. 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). Seagulls are a source of 
numerous coliforms and can also be a source for several human 
pathogens, (Geldreich and Shaw, 1993). 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). Plants, macrophytes and organic debris will add to the biomass 
and nutrient supply.
    State Regulations: In order to assess regulatory requirements at 
the State level, it is necessary to contact individual drinking water 
programs and collect and evaluate specific regulatory language obtained 
from those programs. 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.
    Survey of Ten Utilities: There is no comprehensive information 
available on the number or size of open finished water reservoirs in 
water systems around the country; however, there is one recent survey 
of ten utilities which either have open finished water reservoirs or 
which had them in the past and covered or replaced them (E&S 
Environmental Chemistry, 1997). The existing open reservoirs which were 
operated by these systems varied greatly in size, from 5.5 million 
gallons (MG) to 900 MG. The systems with open finished reservoirs also 
had closed reservoirs within their service area, but for some of the 
systems the open reservoirs represent the largest component of total 
storage volume in the systems.

[[Page 59510]]

    Most of the reservoirs in the systems in this survey were excavated 
and lined, but several of the larger ones were formed by dams or 
natural lakes that had been converted to water supply use. Many of 
these reservoirs have irregular geometry and configurations which make 
covering very difficult or impossible. Others are so large that 
covering them would be impractical. For some of these reservoirs, it is 
impractical to find locations for replacement with the proper hydraulic 
characteristics and size. To partially solve this problem in some 
cases, systems have chosen to leave large existing open reservoirs off-
line, except for emergency supply purposes.
    None of the systems had comprehensive evidence about the effect of 
open reservoirs on water quality. These water systems had instituted a 
number of measures at open reservoirs to control potential sources of 
contamination; these measures included fencing setbacks, security 
cameras, on-site surveillance, rechlorination, wire canopies to control 
bird activity, and other measures.
3. Request for Public Comment
    USEPA is considering as part of the IESWTR a requirement that 
systems cover all new reservoirs, holding tanks or other storage 
facilities for finished water for which construction begins after the 
effective date of the rule. The Agency intends to further consider this 
issue, including whether there should be a requirement that all 
finished water reservoirs, holding tanks and other storage facilities 
be covered, as part of the development of the Long-Term ESWTR. The 
Agency requests further comment on this issue and whether provisions 
should be established to require all new reservoirs, holding tanks, or 
other storage facilities to be covered.

I. Cross Connection Control Program

1. Summary of 1994 Proposal and Public Comments
    The July 29, 1994, Federal Register requested public comment on 
whether the Agency should require States and/or systems to have a 
cross-connection control program. In addition, the Agency solicited 
comment on a number of associated issues, including (1) what specific 
criteria, if any, should be included in such a requirement, (2) how 
often such a program should be evaluated, (3) whether USEPA should 
limit any requirement to only those connections identified as a cross 
connection by the public water system or the State, and (4) conditions 
under which a waiver from this requirement would be appropriate. The 
Agency also requested commenters to identify other regulatory measures 
USEPA should consider to prevent contamination of drinking water in the 
distribution system (e.g., minimum pressure requirements in the 
distribution system).
    Most commenters supported either a federal or State cross 
connection control program. Various commenters recommended that such a 
program include a backflow prevention program with approved backflow 
preventer lists, categorization of all service connections with respect 
to potential risk of backflow, requirement for periodic testing and 
maintenance of backflow prevention devices, periodic review of program 
by State, establishment of an annual backflow device testing program, 
establishment of a backflow device inspector certification program, 
enforcement authority, and other suggestions. Commenters also 
recommended national disinfection procedures for repair of water lines 
and for placing new lines into service, a provision for at least one 
person trained in cross-connection control to carry out the program, 
and other suggestions.
    Commenters opposed to a cross connection control program indicated 
that (1) a federally-mandated program would be impractical, burdensome, 
and would fail, (2) a State program would be more appropriate than an 
USEPA-mandated program, (3) most States already have a comprehensive 
program, thus negating need for federal regulations, (4) USEPA should 
publish general guidelines only, and (5) there should be a separate 
regulation because a cross connection control program would affect both 
surface water and ground water.
2. Overview of Existing Information
    Historically, a significant portion of waterborne disease outbreaks 
reported by CDC are caused by distribution system deficiencies. 
Distribution system deficiencies are defined in CDC's publication 
Morbidity and Mortality Weekly Report as cross connections, 
contamination of water mains during construction or repair, and 
contamination of a storage facility. Between 1971-1994, approximately 
53 waterborne disease outbreaks were associated with cross connections 
or backsiphonage. Fifty-six outbreaks were associated with other 
distribution system deficiencies (Craun, Pers. Comm. 1997b). Some 
outbreaks have resulted from water main breaks or repairs.
    There is no centralized repository where backflow incidents are 
reported or recorded. The vast majority of backflow incidents are 
probably not reported. Specific backflow incidents are described in 
detail in USEPA's Cross-Connection Control Manual (USEPA, 1989a).
    Where cross connections exist, some protection is still afforded to 
the distribution system by the maintenance of a positive water pressure 
in the system. Adequate maintenance of pressure provides a net movement 
of water out through breaks in the distribution pipes and prevents 
contaminated water outside of the pipes from entering the drinking 
water supply. The loss of pressure in the distribution system, less 
than 20 psi, can cause a net movement of water from outside the pipe to 
the inside, possibly allowing the introduction of fecal contamination 
into the system. This problem is of special concern where wastewater 
piping is laid in the same street as the water pipes, creating a 
potential threat to public health whenever there is low or no pressure.
    Many States have cross connection control programs. A Florida 
Department of Environmental Protection survey evaluated cross-
connection control regulations in the 50 states (Florida DEP 1996). The 
survey results showed that 29 of the 40 states that responded to the 
survey request have programs. The rigor of the programs and the extent 
to which they are enforced was not addressed by the survey. An USEPA 
report suggests that the responsibility for administration and 
enforcement of the State programs is generally at the local level 
(USEPA, 1995a).
3. Request for Public Comment
    USEPA does not plan to address cross connection control in the 
IESWTR. As noted above, many States currently have programs, although 
the extent to which these vary is unclear. The Agency does plan to 
consider cross connection control issues during the development of the 
Long-Term ESWTR, in the context of a broad range of issues related to 
distribution systems. USEPA continues to request comments or additional 
information related to cross connection control or other distribution 
system issues.

J. Recycling Filter Backwash Water and Filtering to Waste

    The July 29, 1994, notice requested comment on the extent to which 
the ESWTR should address the issue of recycling filter backwash water, 
given its potential for increasing the densities of Giardia and 
Cryptosporidium on the filters. The 1996 Amendments to the SDWA require 
USEPA to promulgate a

[[Page 59511]]

regulation for filter backwash recycling not later than August 2000, 
(SDWA 1412(b)(14)).
    Most commenters who addressed this issue contended that backwash 
water should not be recycled or that, if it is recycled, it should be 
treated first. One commenter suggested that this decision should be 
based on the pathogen density in the backwash water. Another commenter 
suggested that the rule should include criteria for assessing the 
extent of backwash recycling, depending on raw water quality, size of 
filters, and water volume. Another commenter maintained that this issue 
should be left to the State and system. One commenter suggested that 
the impacts of recycling needed additional research and that any rule 
addressing this issue needed to incorporate the results of the latest 
research.
1. Filter Backwash Recycle Configurations
    Treatment plants can be configured into several general categories 
but the variation within each category is significant.
    One aspect of this treatment variation is how recycling of waste 
streams from plant processes are handled. Figure 4 shows a general 
schematic of a conventional treatment plant and how recycle streams may 
be developed and treated. Note that backwash water treatment is carried 
out in a miniature coagulation-flocculation-sedimentation treatment 
facility. Some utilities are considering microfiltration to replace 
these unit processes.

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[[Page 59512]]

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[[Page 59513]]

    Figure 5 shows an alternate view for some water treatment 
facilities that do not practice treatment of their recycled waste 
streams. There is an almost infinite variety between these two 
examples. In addition, waste streams can be recycled to many different 
points in the treatment train. The most common recycle points are at 
the plant influent or rapid mix. However, there are several known 
examples of recycle streams being introduced into the treatment process 
as late as the filter influent.

BILLING CODE 6560-50-P
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BILLING CODE 6560-50-C
    Figure 6 shows a typical plot of turbidity over time from a filter 
from reintroduction into service after backwash to breakthrough of 
turbidity at the end of the filter run. Some plants have installed 
filter-to-waste facilities which allow the discharge of the first 
minutes of a filter's operation after backwashing usually into the 
backwash reclamation system. In California, the State drinking water 
regulations define filter-to-waste as: ` ``Filter-to-waste'' means a 
provision in a filtration process to allow the first filtered water, 
after backwashing a filter, to be wasted or reclaimed.' (McGuire, 1994)

BILLING CODE 6560-50-P

[[Page 59514]]

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BILLING CODE 6560-50-C
    Figure 7 shows a general schematic of a filter-to-waste operation. 
After the backwash process is complete and the filter influent water is 
allowed to enter the filter, Valve A is operated so that all of the 
filter effluent water is sent to waste. After a specified period of 
time or when it is determined that the ripening spike is largely over, 
Valve A is operated so that the filtered water becomes part of the 
product water of the treatment plant.

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[[Page 59515]]

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BILLING CODE 6560-50-C
2. State Drinking Water Regulations
    California has specific regulations that deal with backwash recycle 
and filter-to-waste. Treatment of backwash recycle flows is covered in 
the design of treatment facilities section. For new construction, 
utilities are required to install solids removal treatment for recycled 
filter backwash water. Also, treated backwash water must be returned to 
the ``headworks'' (i.e., the plant influent) of the treatment plant. 
Solids removal treatment unit processes are not specified in the 
regulation, but new construction must be approved by the California 
Department of Health Services (California Health and Safety Code, 
Sections 646658 & 64660).
    To minimize the filter ripening spike, the California Department of 
Health specifies operational requirements such that filtration rates 
are increased gradually when filters are placed back into service 
following backwashing or any other interruption in the operation of the 
filter. When any individual filter is placed back into service 
following backwashing or other interruption event, the filtered water 
turbidity from that filter cannot exceed any of the following criteria:
     2.0 NTU.
     1.0 NTU in at least 90 percent of the interruption events 
during any consecutive 12-month period.
     0.5 NTU after the filter has been in operation for 4 
hours.
    For new construction, utilities are required to provide filter-to-
waste or add additional coagulant chemicals to backwash water.
3. Literature Overview of Standard of Practice
    a. Treatment Reference Texts. The joint ASCE/AWWA (1990) water 
treatment plant design book includes one section on page 182 dealing 
with washwater disposal and recovery. The section lists several 
possibilities including recycling without treatment, equalization and 
treatment, and lagoons to provide for both equalization and 
sedimentation. On page 188, the backwash recycle facility at the 
Duluth, Minnesota plant is described. Chemical addition, flocculation 
and clarification comprise the backwash treatment system.
    The fourth edition of Water Quality and Treatment contains one 
section on pages 988-989 dealing with filter backwash residuals. The 
section notes that recovery of ``dirty'' backwash water is becoming 
increasingly common and that the volume of backwash water is typically 
one to five percent of total plant production. Flow equalization is 
listed as the most common approach to dealing with recycling of 
backwash water. The section states that ``For conventional plants, 
solid separation before return is not common, and some holding tanks 
are mixed to keep solids in suspension.'' Direct filtration plants are 
noted for needing solids separation

[[Page 59516]]

treatment of backwash water, because there is no sedimentation facility 
in a direct filtration plant. Concerns are expressed in the section 
about increasing the concentrations of Giardia cysts in the plant 
influent with the recycle of untreated backwash water.
    A handbook of practice was published in 1987 dealing with water 
treatment plant waste management. Backwash water was described as a 
major waste stream on page 5 and flow equalization was listed as an 
important requirement. The handbook gives specific examples of the size 
of backwash basins needed based on the number of filters backwashed and 
the backwash frequency. The example discusses tankage volumes that 
would allow a maximum 10 percent recycle rate of the backwash water to 
the plant influent. Neither clarification nor polymer addition were 
mentioned in this early reference (Cornwell et al., 1987).
    b. ICR Treatment Plants. Of the 523 treatment plants subject to the 
ICR, 282 use conventional treatment. Of the conventional treatment 
plants, 146 (or 52%) practice recycling of their backwash water. 
Additionally, 15 direct filtration plants and 3 in-line filter plants 
recycle their backwash water. These data show that a large fraction of 
the surface water treatment plants recycle their backwash water.
    The ICR will provide the first detailed data on the number of 
treatment plants that treat their recycled backwash water and the 
technologies they use and some limited data on backwash water quality. 
Until the initial sampling plan data is available for analysis sometime 
in early 1998, the only information available on the ICR utilities is 
from their Initial Sampling Schematics and that will only show the 
addition of a treatment chemical. The Initial Sampling Schematics do 
not indicate if coagulation, flocculation or sedimentation is used for 
washwater recycle treatment.
    An inspection of those schematics revealed the following 
information on treatment of recycled backwash water. A total of 164 
schematics for plants using conventional treatment, direct filtration 
or in-line filtration were examined. Only 12 of the plants indicated 
that they provided any chemical treatment. Addition of a polymer was 
practiced at 5 plants. Chlorination as the only treatment of the 
recycled washwater was found at 2 plants. A total of 5 plants provided 
both chlorination and polymer treatment of the backwash water.
    c. Cornwell and Lee 1993 Report. Another source of information on 
waste stream quality and the impact of recycling of these streams on 
treated water quality is found in an American Water Works Association 
Research Foundation (AWWARF) 1993 report authored by Cornwell and Lee. 
They studied the quality characteristics of waste streams from 24 
treatment plants and investigated the treatment characteristics in some 
detail at 8 plants.
    Among the contaminants analyzed were Giardia and Cryptosporidium. 
The study found that filter backwash water could have very high cyst/
oocyst concentrations and chemical loads. However, the researchers 
found no finished water quality problems as a result of recycling.
    The study found that backwash water sedimentation was effective in 
reducing particle and pathogen concentrations in the used filter 
backwash water. However, very low overflow rates (less than 0.05 gpm/
sf) of the sedimentation basin were required to achieve the solids 
removal unless a polymer was used. Using an anionic polymer increased 
the particle removals and allowed sedimentation overflow rates of 0.2 
to 0.3 gpm/sf. The last two sentences of the Executive Summary of the 
report provide insight into the overall findings.

    ``The use of equalized, continuous recycle, proper waste stream 
treatment prior to recycle, and characterization of waste stream 
quality through proper monitoring should be used in conjunction with 
recycle operations. If these recommendations are used, recycle can 
be an appropriate part of water treatment operations (Cornwell and 
Lee, 1993).''

    In a paper which summarized the report findings, the authors stated 
a general rule that the recycle streams should be flow equalized and 
blended in to the plant flow over the entire 24 hour plant operating 
cycle. The rule of thumb that the amount of recycle should be less than 
10 percent of the plant flow may not be sufficient, and a lower 
percentage of recycle may have to be practiced depending on the quality 
of the recycled water (Cornwell and Lee, 1994).
    d. Other Studies. In 1996, AWWA conducted a survey of treatment 
plants to determine the extent of backwash water recycling and the 
treatment provided to that water (McGuire, 1997). A total of 400 plants 
from utilities serving more than 100,000 people were contacted. About 
40 percent of those plants responded. Of those responding, about 60 
percent of the plants recycled their filter backwash water. The other 
40 percent appeared to discharge the backwash water to a surface water 
supply or to a sanitary sewer. Of the plants that recycled their 
backwash water, 27 percent responded that they treated the recycle 
water. The important point to note from this limited survey is that 
recycle of backwash water appears to be a common practice among water 
treatment plants.
4. Filter-to-Waste
    One possible concern is the discharge of large number of particles 
from filters that are put back into service after backwashing. Work 
done on Giardia removal by filtration at Fort Collins, Colorado, 
indicated that a filter-to-waste period was not necessary to produce 
low Giardia filter effluent levels as long as proper chemical 
preconditioning of the filter was practiced (Gertig et al. 1988). 
Logsdon et al. studied sedimentation and several different filter media 
from removing Giardia cysts at McKeesport, Pennsylvania. Giardia cyst 
concentrations were found to be higher at the beginning of the filter 
run, indicating that filter-to-waste may be needed to reduce the levels 
of Giardia in the finished water (Logsdon et al, 1985).
    One study (Amirtharajah, 1988) indicated that more than 90% of the 
particles that pass through a filter do so during the initial stages of 
filtration. Another study (Logsdon et al., 1981) found that initial 
cyst concentrations in the effluent, after backwash, were from 10 to 25 
times higher than those in the stabilized filter run, even though the 
difference in turbidity was less than 0.1 NTU. One British study (Hall 
and Croll 1996) found that in one test filter run, calculation of the 
total number of particles released during the whole run showed that up 
to 30% of the particles were released during the first hour of filter 
ripening. The turbidity during this peak was 0.4 NTU. Gradual start of 
the filter after backwashing reduced the peak particle count in the 
effluent. Effectiveness of practicing filter-to-waste in reducing the 
passing of oocysts depends on the duration of the ripening period. For 
example, a 15 minute filter-to-waste period will not be very effective 
for a ripening period of 2 hours. Mid and end-of-run turbidity spikes 
can also pass large number of particles (including pathogen oocysts) 
into the effluent. However, these latter spikes can be controlled by 
avoidance of flow changes and by timely backwashing the filter.
5. Request for Public Comment
    USEPA does not plan to include separate provisions for recycling of 
filter backwash water and filter-to-waste issues in the IESWTR. The 
Agency anticipates that some systems will address these issues as part 
of their efforts to comply with revised turbidity performance standards 
of 0.3 NTU for

[[Page 59517]]

the 95th percentile of monthly measurements and a maximum turbidity 
level of 1 NTU. As previously discussed in this Notice, USEPA is 
required under the 1996 Amendments to the SDWA to issue a regulation to 
address filter backwash recycling by August 2000. USEPA plans to 
develop these regulations in conjunction with the development of the 
Long-Term ESWTR. USEPA continues to request comments or additional 
information related to recycling of filter backwash water or filter-to-
waste issues.

K. Certification Criteria for Water Plant Operators

    The July 29, 1994, notice requested comment on whether the ESWTR 
should define minimum certification criteria for surface water 
treatment plant operators. Currently, the SWTR (141.70) requires such 
systems to be operated by ``qualified personnel who meet the 
requirements specified by the State.'' The 1996 Amendments to the SDWA 
require USEPA to undertake several actions with regard to operator 
certification, including the publication of guidelines specifying 
minimum standards.
    Of the few commenters who addressed this issue most asserted that 
minimum certification criteria for water operators should be left to 
the States. One commenter contended that certified operator(s) should 
be on site at all times and that a non-certified operator should never 
be in charge. Another respondent noted that rewording Sec. 141.70 to 
read ``personnel who are certified by the State, or can obtain 
certification within one year of date of employment'' will adequately 
define certification criteria.
    Consistent with the 1996 SDWA amendments, USEPA appointed an 
Operator Certification Working Group of the National Drinking Water 
Advisory Council (NDWAC) to form a partnership with States, water 
systems and the public to develop information on recommended operator 
certification requirements. USEPA will publish guidelines specifying 
minimum standards for certification (and recertification) of operators 
of community and nontransient noncommunity public water systems. USEPA 
is developing the draft guidelines based on recommendations from the 
NDWAC. The draft guidelines, when available, will be published in the 
Federal Register for public review and comment. Members of the public 
who are interested in further information regarding this effort may 
contact Richard Naylor of USEPA's Office of Ground Water and Drinking 
Water at 202-260-5135 or at e-mail address: 
[email protected].

L. Regulatory Compliance Schedule and Other Compliance-Related Issues

A. Regulatory Compliance Schedule
Background
    During the 1992 Disinfectants/Disinfection Byproducts Regulatory 
Negotiation (reg-neg) that resulted in the 1994 proposed Stage 1 DBPR 
and proposed IESWTR, there was extensive discussion of the compliance 
schedule and applicability to different groups of systems and 
coordination of timing with other regulations.
    In addition to the Stage 1 DBPR, the Negotiating Committee agreed 
that EPA would (a) propose an interim ESWTR which would apply to 
surface water systems serving 10,000 or more people, and (b) at a later 
date, propose a long-term ESWTR applying primarily to small systems 
under 10,000. Both of these microbial rules would be proposed and 
promulgated so as to be in effect at the same time that systems of the 
respective size categories would be required to comply with new 
regulations for disinfectants and DBPs. Finally, although the GWDR was 
not specifically addressed during the reg-neg, EPA anticipated that it 
would be promulgated at about the same time as the IESWTR and Stage 1 
DBPR.
    EPA proposed a staggered compliance schedule, based on the reg-neg 
results. The Negotiating Committee and EPA believed that such a process 
was needed for the rules to be properly implemented by both States and 
PWSs. Also, EPA proposed a staggered schedule to achieve the greatest 
risk reduction by providing that larger water systems were to come into 
compliance earlier than small systems (to cover more people earlier), 
and surface water systems were to come into compliance earlier than 
ground water systems (since the potential risks of both pathogens and 
DBPs were considered generally higher for surface water systems). Large 
and medium size surface water PWSs (serving at least 10,000 people) 
constitute less than 25% of community water systems using surface water 
and less than 3% of the total number of community water systems, but 
serve 90% of the population using surface water and over 60% of the 
population using water from community water systems. These large PWSs 
are also those with experience in simultaneous control of DBPs and 
microbial contaminants. EPA proposed that these systems be required to 
comply with the Stage 1 DBPR and IESWTR 18 months after promulgation of 
the rules and that States would be required to adopt the rules no later 
than 18 months after promulgation. These 18 month periods were 
prescribed in the 1986 SDWA Amendments.
    Surface water PWSs serving fewer than 10,000 people were to comply 
with the Stage 1 DBPR requirements 42 months after promulgation, to 
allow such systems to simultaneously come into compliance with the 
LTESWTR. This compliance date reflected a schedule that called for the 
LTESWTR to be promulgated 24 months after the IESWTR was promulgated 
and for PWSs then to have 18 months to come into compliance. Such a 
simultaneous compliance schedule was intended to provide the necessary 
protection from any downside microbial risk that might otherwise result 
when systems of this size attempted to achieve compliance with the 
Stage 1 DBPR.
    Ground water PWSs serving at least 10,000 people would also be 
required to achieve compliance with the Stage 1 DBPR 42 months after 
promulgation. A number of these systems, due to recently installing or 
upgrading to meet the GWDR (which EPA planned to promulgate at about 
the same time as the Stage 1 DBPR), were expected to need some period 
of monitoring for DBPs in order to adjust their treatment processes to 
also meet the Stage 1 DBPR standards.
1996 Safe Drinking Water Act Amendments
    The SDWA 1996 Amendments affirmed several key principles underlying 
the M-DBP compliance strategy developed by EPA and stakeholders as part 
of the 1992 Regulatory Negotiation process. First, under Section 
1412(b)(5)(A), Congress recognized the critical importance of 
addressing risk/risk tradeoffs in establishing drinking water standards 
and gave EPA the authority to take such risks into consideration in 
setting MCL or treatment technique requirements. Second, Congress 
explicitly adopted the staggered M-DBP regulatory development schedule 
developed by the Negotiating Committee. Section 1412(b)(2)(C) requires 
that the standard setting intervals laid out in EPA's proposed ICR rule 
be maintained even if promulgation of one of the M-DBP rules was 
delayed. As noted above, this staggered regulatory schedule was 
specifically designed as a tool to minimize risk/risk tradeoff. A 
central component of this approach was the concept of ``simultaneous 
compliance'' which provides that a PWS must comply with new microbial 
and DBP requirements at the same time to assure

[[Page 59518]]

that in meeting a set of new requirements in one area, a facility does 
not inadvertently increase the risk (i.e., the risk ``tradeoff'') in 
the other area.
    The SDWA 1996 Amendments also changed two statutory provisions that 
elements of the 1992 Negotiated Rulemaking Agreement were based upon. 
As outlined above, the 1994 Stage 1 DBPR and ICR proposals provided 
that 18 months after promulgation large PWSs would comply with the 
rules and States would adopt and implement the new requirements. 
Section 1412(b)(10) of the SDWA as amended now provides that drinking 
water rules shall become effective 36 months after promulgation (unless 
the Administrator determines that an earlier time is practicable or 
that additional time for capital improvements is necessary--up to two 
years). In addition, Section 1413(a)(1) now provides that States have 
24 instead of the previous 18 months to adopt new drinking water 
standards that have been promulgated by EPA.
Discussion
    In light of the 1996 SDWA amendments, developing a compliance 
deadline strategy that encompasses both the Stage 1 DBPR and IESWTR, as 
well the related LTESWTR and Stage 2 DBPR, is a complex challenge. On 
the one hand, such a strategy needs to reflect new statutory 
provisions. On the other, it needs to continue to embody key reg-neg 
principles reflected in both the 1994 ICR and Stage 1 DBPR proposals; 
principles that both Congressional intent and the structure of the new 
Amendments, themselves, indicate must be maintained.
    An example of the complexity that must be addressed is the 
relationship between the principles of risk/risk tradeoff, simultaneous 
compliance, and the staggered regulatory schedule adopted by Congress. 
Under the 1996 SDWA amendments, the staggered regulatory deadlines 
under Section 1412(b)(2)(C) call for the IESWTR and Stage 1 DBPR to be 
promulgated in November 1998 and the LTESWTR in November of 2000. 
However, a complicating factor reflected in the Negotiated Rulemaking 
Agreement of 1992 and contained in the 1994 ICR, IESWTR, and Stage 1 
DBPR proposals, is that Stage 1 applies to all PWSs, while IESWTR 
applies only to PWSs over 10,000, and the LTESWTR covers remaining 
surface water systems under 10,000.
    One approach might be to simply provide that each M-DBP rule 
becomes effective 3 years after promulgation in accordance with the new 
SDWA provisions. For surface water systems over 10,000, each plant 
would be required to comply with related microbial and DBP requirements 
at the same time thereby minimizing potential risk/risk tradeoffs. For 
surface water systems under 10,000, however, this approach would result 
in a very large number of smaller plants complying with DBP 
requirements two years before related LTESWTR microbial provisions 
became effective, thereby creating an unbalanced risk tradeoff 
situation that the Negotiating Committee, EPA, and Congress each sought 
to avoid.
    As this example suggests, given the staggered regulatory 
development schedule developed by stakeholders in the reg-neg process 
and adopted by Congress, there is a difficult inconsistency between the 
principle of avoiding risk tradeoffs, simultaneous compliance, and 
simply requiring all facilities to comply with applicable M-DBP rules 
three years after their respective promulgation. The challenge, then, 
is to give the greatest possible meaning to each of the new SDWA 
provisions while adhering to the fundamental principles also endorsed 
by Congress of addressing risk-risk tradeoffs and assuring simultaneous 
compliance.
    A further question that must be factored into this complex matrix 
is how to address the relationship between promulgation of a particular 
rule, its effective date, and its adoption by a primacy State 
responsible for implementing the Safe Drinking Water Act. Under the 
1994 IESWTR and Stage 1 DBPR proposals, the rule's 18 month effective 
date was the same as the 18 month date by which a State was required to 
adopt it. This approach reflected the 18 month SDWA deadlines 
applicable during reg-neg negotiations and at the time of proposal.
    The difficulty with requiring PWS compliance and State 
implementation by the same date is that States may not have enough lead 
time to adopt rules, train their own staff, and develop policies to 
implement and enforce new rules by the deadline for PWS compliance. In 
situations where the new rules are complex and compliance requires 
state review and ongoing interaction with PWSs, successful 
implementation can be very difficult, particularly for States with many 
small systems that have smaller staffs and fewer resources to 
anticipate the requirements of final rules. As noted above, Congress 
addressed this issue by extending the time for States to put their own 
rules in place from 18 months to two years after federal promulgation 
and, then, by generally providing for a one year interval before PWSs 
must comply (three years after promulgation). As a result, the 18 month 
interval contemplated by the 1994 proposals is no longer applicable, 
and the approach of setting the same date for PWS compliance and State 
rule implementation is no longer consistent with the phased approach 
laid out in the new SDWA amendments.
    A final set of issues that must be addressed in connection with the 
Stage 1 DBPR proposal are compliance deadlines for ground water systems 
that currently disinfect. Reflecting the Negotiated Rulemaking 
Agreement, the 1994 proposal provided that ground water systems serving 
at least 10,000 that disinfect must comply three and one half years (42 
months) after Stage 1 DBPR promulgation. Small ground water systems 
serving fewer than 10,000 that disinfect would be required to come into 
compliance five years (60 months) after Stage 1 DBPR promulgation. 
Again, the challenge here is to reconcile new statutory compliance 
provisions with the principles of simultaneous compliance, avoiding 
risk/risk tradeoffs, and deference to Congress' clear intent to 
preserve the ``delicate balance that was struck by the parties in 
structuring the negotiated rulemaking agreement''. (Joint Explanatory 
Statement of the Committee on Conference on S.1316, p2). An additional 
factor that must be considered in this context is that Congress 
affirmed the need for microbial ground water regulations but also 
clearly contemplated that such standards might not be promulgated until 
issuance of Stage 2 DBPR (no later than May, 2002).
Alternative Approaches
    In light of the 1996 SDWA amendments and their conflicting 
implications for different elements of the compliance strategy agreed 
to by the Negotiating Committee and set forth in the 1994 IESWTR and 
Stage 1 DBPR proposals, EPA is today requesting comment on four 
alternative compliance approaches. The Agency also requests comment on 
any other compliance approaches or modifications to these options that 
commenters believe may be appropriate.

[[Page 59519]]



                                   Option 1.--Implement 1994 Proposal Schedule                                  
----------------------------------------------------------------------------------------------------------------
                                                             Surface water PWS             Ground water PWS     
                 Rule  (promulgation)                  ---------------------------------------------------------
                                                        10k      <10k     10k      <10k   
----------------------------------------------------------------------------------------------------------------
DBP 1 (11/98).........................................           5/00          5/02           5/02         11/03
IESWTR (11/98)........................................           5/00            NA             NA            NA
LTESWTR (11/00).......................................       \1\ 5/02          5/02             NA            NA
GWDR (11/00)..........................................             NA            NA          (\2\)         (\2\)
----------------------------------------------------------------------------------------------------------------
\1\ (If required).                                                                                              
\2\ Not addressed.                                                                                              

    Option 1 (schedule as proposed in 1994) simply continues the 
compliance strategy laid out in the 1994 Stage 1 DBPR and IESWTR 
proposals. This would provide that medium and large surface water PWSs 
(those serving at least 10,000 people) comply with the final Stage 1 
DBPR and IESWTR within 18 months after promulgation, and that surface 
water systems serving fewer than 10,000 comply within 42 months of 
Stage 1 DBPR promulgation. This option also would provide that ground 
water systems serving at least 10,000 and that disinfect comply within 
42 months, while ground water systems serving fewer than 10,000 comply 
within 60 months.
    This approach was agreed to by EPA and other stakeholder members of 
the 1992 Negotiating Committee. However, it has been at least in part 
superseded by both the general 36 month PWS compliance period and the 
24 month State adoption and implementation period provided under the 
1996 SDWA amendments. If the proposed 1994 compliance schedule were to 
be retained, EPA would need to make a determination that the statutory 
compliance provision of 36 months was not necessary for large and 
medium surface systems because compliance within 18 months is 
``practicable''. To maintain simultaneous compliance, the Agency would 
also have to make the same practicability determination for small 
surface water systems in complying with the LTESWTR and for ground 
water systems serving at least 10,000 in complying with the GWDR. In 
addition, the Agency would need to justify 42 months for small surface 
water systems and 60 months for small ground water systems with 
disinfection by making a national determination that the additional 
time was required due to the need for capital improvements at each of 
these small systems. EPA also would need to articulate a rationale for 
why States should not be provided the statutorily specified 24 months 
to implement new complex regulatory provisions before PWSs are required 
to comply. Finally, to implement this approach, the Agency would be 
required to modify the timing associated with the microbial backstop 
provision agreed to on July 15, 1997 by the M-DBP Advisory Committee 
(since a 18 month schedule would not allow time after promulgation for 
medium surface water systems (10,000-99,999) to collect HAA data prior 
to having to determine whether disinfection benchmarking is necessary).
    EPA requests comment on the issues outlined above in connection 
with this option. In particular, the Agency requests comment and 
information to support a finding that compliance by specified systems 
in 18 months is practicable for some rules, and that extensions to 42 
or 60 months for other systems are required to allow for capital 
improvements.

                               OPTION 2.--Add 18 Months to 1994 Proposal Schedule                               
----------------------------------------------------------------------------------------------------------------
                                                             Surface water PWS             Ground water PWS     
                  Rule (promulgation)                  ---------------------------------------------------------
                                                        10k      <10k     10k      <10k   
----------------------------------------------------------------------------------------------------------------
DBP 1 (11/98).........................................          11/01         11/03          11/03          5/05
IESWTR (11/98)........................................          11/01            NA             NA            NA
LTESWTR (11/00).......................................      \1\ 11/03         11/03             NA            NA
GWDR (11/00)..........................................             NA            NA          (\2\)         (\2\)
----------------------------------------------------------------------------------------------------------------
\1\ (If required).                                                                                              
\2\ Not addressed.                                                                                              

    Option 2 (each date in proposed 1994 compliance strategy extended 
by 18 months) reflects the fact that the 1996 SDWA amendments generally 
extended the previous statutory deadlines by 18 months (to three years) 
and established an overall compliance period not to extend beyond 5 
years. This second approach would result in simultaneous compliance for 
surface water systems. Large surface water systems (those serving at 
least 10,000) would have three years to comply in accordance with the 
baseline 3 year compliance period established under Section 1412(b)(10) 
of the 1996 Amendments.
    Small surface water systems (under 10,000) would be required to 
comply with Stage 1 D/DBPR requirements within five years and 
applicable LTESWTR requirements within three years. Since the LTESWTR 
will be promulgated two years after Stage 1 DBPR (in accordance with 
the new SDWA M-DBP regulatory deadlines discussed above), the net 
result of this approach is that small surface water systems would be 
required to comply with both Stage 1 DBPR and IESWTR requirements by 
the same end date of November 2003, thus assuring simultaneous 
compliance. This meets the objective of both the reg-neg process and 
Congress to address risk-risk tradeoffs in implementing new M-DBP 
requirements.
    USEPA believes that providing a five year compliance period for 
small surface water systems under the Stage 1 DBPR is appropriate and 
warranted under section 1412(b)(10), which expressly allows five years 
where necessary for capital improvements. Of necessity, capital 
improvements require

[[Page 59520]]

preliminary planning and evaluation. Such planning requires, perhaps 
most importantly, identification of final compliance objectives. This 
then is followed by an evaluation of compliance alternatives, site 
assessments, consultation with appropriate state and local authorities, 
development of final engineering and construction designs, financing, 
and scheduling. In the case of the staggered M-DBP regulatory schedule 
established as part of the 1996 SDWA amendments, LTESWTR microbial 
requirements for small systems are required to be promulgated two years 
after the establishment of Stage 1 DBPR requirements. Under these 
circumstances, small systems will not even know what their final 
combined M-DBP compliance obligations are until Federal Register 
publication of the final LTESWTR. As a result, an additional two year 
period reflecting the two year Stage 1 DBPR/LTESWTR regulatory 
development interval established by Congress is required to allow for 
preliminary planning and evaluation which is an inherent component of 
any capital improvement process. EPA believes this approach is 
consistent with both the objective of assuring simultaneous compliance 
and not exceeding the overall statutory compliance period of five 
years. This same logic would also apply to ground water systems serving 
at least 10,000, since such systems would need the final GWDR to 
determine and implement a compliance strategy.
    With regard to extended compliance schedules, EPA notes that the 
economic analysis developed as part of the M-DBP Advisory Committee 
indicates that there will be capital costs associated with 
implementation of both the IESWTR as well as the Stage I DBP rules. As 
outlined above, the 1996 SDWA amendments provide that a two year 
extension may be provided by EPA at the national level or by States on 
a case-by-case basis if either EPA or a State determines that 
additional time is necessary for capital improvements. EPA does not 
believe there is data presently in the record for either of these 
rulemakings to support a national determination by the Agency that a 
two-year extension is justified. EPA requests comment on this issue 
and, if a commenter believes such an extension is warranted, requests 
that the comments provide data to support such a position.
    Adding 18 months to the 1994 proposed compliance strategy would 
result in 78 month (six and a half year) compliance period for small 
ground water systems. This is beyond the overall five year compliance 
period established by Congress under Section 1412(b)(10). EPA is not 
aware of a rationale to support this result that is consistent with 
both the objectives of the reg-neg process and the new SDWA amendments; 
however, the Agency requests comment on this issue. As discussed below, 
EPA believes there is a reasonable compliance strategy for addressing 
ground water systems that reflects the requirements of the SDWA 
amendments as well as the intent of the reg-neg process.

                 OPTION 3.--Require Compliance With All Rules Within Three Years of Promulgation                
----------------------------------------------------------------------------------------------------------------
                                                             Surface water PWS             Ground water PWS     
                  Rule (promulgation)                  ---------------------------------------------------------
                                                        10k      <10k     10k      <10k   
----------------------------------------------------------------------------------------------------------------
DBP 1 (11/98).........................................          11/01         11/01          11/01         11/01
IESWTR (11/98)........................................          11/01            NA             NA            NA
LTESWTR (11/00).......................................      \1\ 11/03         11/03             NA            NA
GWDR (11/00)..........................................             NA            NA          11/03         11/03
----------------------------------------------------------------------------------------------------------------
\1\ (If required).                                                                                              

    Under this approach, all systems would be required to comply with 
Stage 1 DBPR, IESWTR, and LTESWTR within three years of final 
promulgation. This approach reflects the baseline three year compliance 
period included as part of the new SDWA compliance provisions. Unlike 
option 2 outlined above which simply adds an 18 month extension to the 
1994 proposed compliance approach, this option is not tied to the 1994 
proposal. Rather it applies the new baseline three year compliance 
period to the staggered M-DBP regulatory development schedule which was 
also established as part of the 1996 SDWA amendments.
    This approach would result in simultaneous compliance for large 
surface water systems. However, it would eliminate the possibility of 
simultaneous compliance for small surface water systems and all ground 
water systems. Contrary to reg-neg objectives and Congressional intent, 
it would create an incentive for risk/risk tradeoffs on the part of 
small surface water systems who would be required to take steps to 
comply with Stage 1 DBPR provisions two years before coming into 
compliance with the LTESWTR, and for all ground water systems who would 
be required to take steps to comply with Stage 1 DBPR provisions two 
years before coming into compliance with the GWDR.

                     OPTION 4.--Merge SDWA Provisions With Negotiated Rulemaking Objectives                     
----------------------------------------------------------------------------------------------------------------
                                                             Surface water PWS             Ground water PWS     
                  Rule (promulgation)                  ---------------------------------------------------------
                                                        10k      <10k     10k      <10k   
----------------------------------------------------------------------------------------------------------------
DBP 1 (11/98).........................................          11/01         11/03          11/03         11/03
IESWTR (11/98)........................................          11/01            NA             NA            NA
LTESWTR (11/00).......................................      \1\ 11/03         11/03             NA            NA
GWDR (11/00)..........................................             NA            NA          11/03         11/03
----------------------------------------------------------------------------------------------------------------
\1\ (If required).                                                                                              

    This option combines the principle of simultaneous compliance with 
the revised compliance provisions reflected in the 1996 SDWA 
amendments. Large surface water systems would be required to comply 
with Stage 1 DBPR

[[Page 59521]]

and IESWTR within 3 years of promulgation, thus assuring simultaneous 
compliance and consistency with the baseline statutory compliance 
period of 3 years. Small surface water systems under 10,000 would 
comply with the provisions of the Stage 1 DBPR at the same time they 
are required to come into compliance with the analogous microbial 
provisions of the LTESWTR. This would result in small surface water 
systems simultaneously complying with both the LTESWTR and Stage 1 DBPR 
requirements. Under this approach, small systems would comply with 
LTESWTR requirements three years after promulgation and Stage 1 DBPR 
requirements five years after promulgation. For the reasons articulated 
under option two above, EPA believes providing a five year compliance 
period under Stage 1 DBPR is appropriate and necessary to provide for 
capital improvements.
    For ground water systems, the 1994 proposed Stage 1 DBPR compliance 
schedules provided for only one half of the risk-risk tradeoff balance. 
They did not include a companion rule development and compliance 
schedules for the analogous microbial provisions of a Ground Water 
Disinfection Rule. The 1996 SDWA amendments provide an outside date for 
promulgation of ground water microbial requirements of ``no later 
than'' May 2002, but leave to EPA the decision of whether an earlier 
promulgation is more appropriate. In light of the reg-neg emphasis and 
Congressional affirmation of the principal of simultaneous compliance 
to assure no risk-risk tradeoffs, EPA has developed a ground water 
disinfection rule promulgation schedule that will result in a final 
GWDR by November 2000, the same date as the Congressional deadline for 
the LTESWTR. Ground water systems would be required to comply with the 
GWDR by November 2003, three years after promulgation, and to assure 
simultaneous compliance with DBP provisions, such systems would be 
required to comply with Stage 1 DBPR requirements by the same date. 
Again, for the reasons outlined under option 2, USEPA believes a five 
year compliance period for ground water systems is necessary and 
appropriate.
    Option 4 assures that ground water systems will be required to 
comply with Stage 1 DBPR provisions at the same time that they comply 
with the microbial provisions of the Ground Water Disinfection Rule 
(GWDR). Successful implementation of this option requires that EPA 
develop and promulgate the GWDR by November 2000 as indicated above. 
The Agency recognizes that this is an ambitious schedule, but believes 
it is necessary to meet the twin objectives of simultaneous 
implementation and consistency with the new statutory compliance 
provisions of the 1996 SDWA. In evaluating this option, the Agency also 
considered the possibility of meeting these twin objectives in a 
somewhat different fashion by delaying final promulgation of the Stage 
I DBP rule as it applies ground water systems until the promulgation of 
the GWDR. This alternative possibility would assure simultaneous 
compliance and also provide a ``safety net'' in the event that the GWDR 
November 2000 promulgation schedule is delayed. EPA is concerned, 
however, that this approach may not meet or be consistent with new SDWA 
requirements which provide that the Stage I DBPR be promulgated by 
November 1998. The Agency requests comment on this issue.
Recommendation
    EPA has evaluated each of the considerations identified in Options 
1 through 4. On balance, the Agency believes that Option 4 is the 
preferred option. The primary reasons are (1) to allow States at least 
two years to adopt and implement M-DBP rules consistent with new two 
year time frame provided for under the 1996 SDWA amendments, (2) to 
match the compliance schedules for the LTESWTR and Stage 1 DBPR for 
small (<10,000 served) surface water systems to allow time for capital 
improvements and addressing risk-risk tradeoff issues, and (3) to 
assure that all ground water systems simultaneously comply with newly 
applicable microbial and Stage 1 DBPR requirements on the same 
compliance schedule provided for small surface water systems.
Request for Comments
    EPA requests comment on both the compliance schedule options 
discussed above and on any other variations or combinations of these 
options. EPA also requests comment on its preferred option 4 and on the 
underlying rationale for allowing a five year compliance schedule for 
ground water and small surface water systems under the Stage 1 DBPR.

B. Compliance Violations and State Primacy Obligations

    A public water system that fails to comply with any applicable 
requirement of the SDWA (as defined in 1414 (I)) is subject to an 
enforcement action and a requirement for public notice under the 
provisions of section 1414. Applicable requirements include, but are 
not limited to, MCLs, treatment techniques, monitoring and reporting. 
These regulatory requirements are set out in 40 CFR l41.
    The SDWA also requires States that would have primary enforcement 
responsibility for the drinking water regulations (``primacy'') to 
adopt regulations that are no less stringent than those promulgated by 
EPA. States must also adopt and implement adequate procedures for the 
enforcement of such regulations, and keep records and make reports with 
respect to these activities in accordance with EPA regulations. 5 
U.S.C. 1413. EPA may promulgate regulations that require States to 
submit reports on how they intend to comply with certain requirements 
(e.g., how the State plans to schedule and conduct sanitary surveys 
required by the IESWTR), how the State plans to make certain decisions 
or approve PWS-planned actions (e.g., approve significant changes in 
disinfection under the IESWTR or approve Step 2 DBP precursor removals 
under the enhanced coagulation requirements of the Stage I DBPR), and 
how the State will enforce its authorities (e.g., correct deficiencies 
identified by the State during a sanitary survey within a specified 
time). The primacy regulations are set out in 40 CFR 142.
    EPA drafted requirements for both the PWSs (part 141) and the 
primacy States (part 142) in the proposed rules. EPA is requesting 
comments on whether there are elements of the Advisory Committee's 
recommendations in this Notice that should be treated as applicable 
requirements for the PWS and included in part l41 as enforceable 
requirements. Similarly, EPA requests comments on whether there are 
elements of the Advisory Committee's recommendations in this Notice 
that should be treated as requirements for States and included in part 
142 as primacy requirements.

C. Compliance With Current Regulations

    EPA reaffirms its commitment to the current Safe Drinking Water Act 
regulations, including those related to microbial pathogen control and 
disinfection. Each public water system must continue to comply with the 
current rules while new microbial and disinfectants/disinfection 
byproducts rules are being developed.

M. Disinfection Studies

1. New Giardia Inactivation Studies at High pH Levels
    The Surface Water Treatment Rule (SWTR) requires plants treating 
surface

[[Page 59522]]

water to meet minimum inactivation/removal requirements for Giardia 
cysts and viruses. Under the SWTR, the concept of CT values 
(disinfectant residual concentration (C ) multiplied by contact time 
(T)) is used for estimating inactivation efficiency of disinfection 
practices in plants. As a supplement to the rule, USEPA published a 
guidance manual document entitled ``Guidance Manual for Compliance with 
the Filtration and Disinfection Requirements for Public Water Systems 
Using Surface Water Sources'' (USEPA 1991a) [SWTR Guidance Manual]. In 
this manual, CT tables (Log inactivation versus CT values under 
different environmental conditions) are provided to utilities as a 
guidance in carrying out the disinfection requirements.
    The SWTR Guidance Manual did not include CT values at pH values 
above 9 due to the limited research results available at the time of 
rule promulgation. pH values above 9 mainly exist in plants with lime 
softening processes. An approach for extending the existing CT tables 
in the SWTR Guidance Manual to the upper pH boundary (pH 11.5) that may 
occur in some plants is presented below. With this approach, the latest 
available data reported by Logsdon et al. (1994) was used as a basis 
for CT values at high pH values by applying a linear regression to 
Logsdon's experimental results in laboratory water and a safety factor 
to cover the variability in natural water.
    Analysis of Logsdon's Data: Logsdon et al. (1994) performed Giardia 
inactivation experiments with free chlorine in both laboratory and 
natural waters at 5 deg.C and at pH values of 9.5, 10.5, and 11.5. The 
analysis of MW-s's data is performed with the following assumptions:
    1. Since the experimental data of MW-s et al. for CT values vs. log 
inactivation are relatively scattered, a sophisticated model will not 
improve the result of simulation. Rather, a linear regression was used 
to fit these data points, by assuming the dilution coefficient n=1 in 
the conventional Watson's Law (first-order kinetics).
    2. Data points for inactivation greater than 3-logs in the Logsdon 
et al. report are not included in the linear regression because of 
their uncertainty.
    3. Data points for natural water have a greater variability than 
those for laboratory water. Also, CT tables in the SWTR Guidance Manual 
were developed solely based on tests using laboratory water. To ensure 
consistency, therefore, data points for natural water from the Logsdon 
et al. study were not used. However, a safety factor was applied to the 
CT values estimated from laboratory data to reflect the variability of 
inactivation results in natural water.
    4. To be consistent, the safety factor of CT values at pH > 9 is 
assumed to be the same as that for the existing CT values in the SWTR 
Guidance Manual at pH  9. To appropriately quantify a safety 
factor being applied to obtain those existing CT values in the SWTR 
Guidance Manual, the previous data base for pH  9 was 
reevaluated and interpreted in the same manner as that for pH > 9 
(using a linear regression and a safety factor). Subsequently, the 
safety factor was set at a value such that, if multiplied by the CT 
values estimated by a linear regression, the resultant CT values would 
match the existing CT values in the SWTR Guidance Manual.
    5. For determination of a safety factor, data from the following 
studies were considered: Jarroll et al. (1981), Rice et al. (1982), 
Hibler et al. (1987), and Rubin et al. (1989) [Those data were used as 
a basis for developing the existing CT values in the SWTR Guidance 
Manual.]. Only the data from Jarroll et al. (1981) were used in the 
linear regression because the protocols or conditions in other studies 
are not comparable to those used in the study by Logsdon et al. (1994), 
as noted below:

    (1) The study by Hibler et al. (1987) was based on animal 
infectivity tests. Excystation was used in the study by Logsdon et 
al. (1994).
    (2) The study by Rubin et al. (1989) was conducted only at 
15 deg.C while the study by Logsdon et al. (1994) was performed at 
5 deg.C.
    (3) No data for control excystation was shown in the study by 
Rice et al. (1982) and therefore this data was not used in the 
regression analysis.

    The data from Jarroll et al. (1981) for chlorine concentrations of 
4 and 8 mg/L were not used in the regression analysis because the 
chlorine residual in the study by Logsdon et al. (1994) was no higher 
than 2.1 mg/L.
    The Results of Data Analysis: The data from Jarroll et al. (1981) 
pertaining to log inactivation versus CT values are plotted in Figures 
8--10 for pH values of 6, 7, and 8, respectively. Because Jarroll et 
al. found that essentially no inactivation at pH values of 6-8 was 
observed in control samples in which no disinfectant was added within 
60 minutes (i.e., CT = 0, log inactivation = 0), the intercept of the 
linear regression line was zero.

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    The regression results with the values of the Watson coefficient k 
are shown in each figure. Based on these results, CT values for a 
designated log inactivation at the three different pH values are 
estimated and shown in Table 6. By trials, it is found that if a safety 
factor of 1.5 is applied to those estimated CT values, the resulting CT 
values approximate the values in the SWTR Guidance Manual for chlorine 
concentration  2 mg/L: at pH 6, the safety-factored CT 
values are slightly higher than those in the SWTR Guidance Manual; at 
pH 7, the safety-factored CT values are about in the middle of the 
range of CT values in the SWTR Guidance Manual; at pH 8, the safety-
factored CT values are in the low range of CT values in the SWTR 
Guidance Manual. Therefore, a safety factor of 1.5 appears appropriate 
for the development of CT tables at higher pHs.

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    The Logsdon data for Giardia inactivation with chlorine are shown 
in Figures 11-13 for pH values of 9.5, 10.5, and 11.5, respectively. 
Since Logsdon et al. (1994) also observed that little or no 
inactivation was caused by a high pH itself (i.e., non-disinfected lime 
softened water) in at least 6 hours, the intercept of the linear 
regression line should be zero. Based on the determinant k values 
indicated in each Figure, CT values required for inactivation in the 
range of 0.5-3 log at pH values of 9.5-11.5 and temperature of 5 deg.C 
are estimated and tabulated in Table 7. To evaluate the adequacy of the 
safety factor value (1.5), the line of log inactivation versus the 
safety-factored CT values is also shown in each of Figures 11-13. It 
can be seen from Figures 11 and 12 that most data points for natural 
water are above the safety-factored line, and few points are near the 
line, indicating the safety factor of 1.5 is appropriate for the 
establishment of CT tables for pH > 9.

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  Table 7.--Estimated CT Values for pH=9.5-11.5 at C  2 mg/L 
    and at 5 deg.C--Based on the Logsdon's Study for Laboratory Water   
------------------------------------------------------------------------
                                                    Estimated  Estimated
                 pH                        Log      CT mg-min/   CT  x  
                                      inactivation      L       1.5 S.F.
------------------------------------------------------------------------
pH=9.5..............................          0.5          21         32
                                                1          42         63
                                              1.5          62         93
                                                2          83        124
                                              2.5         104        156
                                                3         125        188
pH=10.5.............................          0.5          70        105
                                                1         141        212
                                              1.5         211        316
                                                2         282        423
                                              2.5         352        528
                                                3         422        633
pH=11.5.............................          0.5         128        192
                                                1         256        384
                                              1.5         385        578
                                                2         513        770
                                              2.5         641        962
                                                3         769       1154
------------------------------------------------------------------------

    By comparing the data in Table 6 and 10, it is seen that estimated 
CT values at pH 9.5 are consistently lower than those at pH 8 in the 
SWTR Guidance Manual. To maintain the consistency of an increasing 
trend of CT values with an increasing pH and be conservative for 
compliance purposes, the mathematical model described in the SWTR 
Guidance Manual (equation 15 in Appendix F) by Clark and Regli (1993) 
is used to extend the existing CT tables in the SWTR Guidance Manual to 
pH=9.5, e.g., CT=60 mg/L for 0.5 log inactivation with 1 mg/L of 
chlorine at 5 deg.C. As proposed in the SWTR Guidance Manual, the 
equation can be directly applied to estimate CT values for 0.5 and 
5 deg.C, and a twofold decrease in CT values for every 10 deg.C 
increase in temperature can be assumed when it is higher than 5 deg.C. 
Consequently, the CT

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values for Giardia inactivation with free chlorine at pH 9.5 are 
computed and shown in Table 8.
    The same temperature correction factor above is used to estimate CT 
values for pH values of 10.5 and 11.5 at temperature from 5 to 
25 deg.C, and 1.5 of temperature factor is applied to convert CT values 
at 5 deg.C to those at 0.5 deg.C. Subsequently, the safety-factored CT 
values for Giardia inactivation with free chlorine were estimated and 
summarized in Tables 11 and 13 for pH values of 10.5 and 11.5, 
respectively. It should be mentioned that although the level of 
chlorine residual (the C value) may affect CT values shown in Tables 12 
and 13, it is recommended that those values are only applicable to a C 
value up to 3 mg/L, at least until more research data become available.

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    In summary, the CT table for Giardia inactivation with free 
chlorine at pH 9.5 was developed by using the same approach in the SWTR 
Guidance Manual for the existing CT tables at lower pH values. For the 
development of CT tables at pH values of 10.5 and 11.5, the data 
reported by Logsdon et al. (1994) was used with a linear regression 
multiplied by a safety factor of 1.5. The new CT values are shown in 
Tables 11, 12, and 13 for pH values of 9.5, 10.5, and 11.5, 
respectively. USEPA solicits comment on the approach taken and whether 
the CT values shown in Tables 11, 12 and 13 are appropriate for 
revising existing guidance for estimating inactivation efficiencies for 
chlorine at pHs above 9. USEPA also solicits comment on other 
approaches for developing criteria by which systems could estimate 
inactivation efficiencies at pHs above 9.
2. Effectiveness of Different Disinfectants on Cryptosporidium
    When the ESWTR was proposed in 1994, USEPA recognized that chlorine 
disinfectants were relatively ineffective in inactivating 
Cryptosporidium, but was not certain if alternative disinfectants might 
be more effective than chlorine. No public comment addressed this issue 
directly. Studies since the proposal have confirmed the ineffectiveness 
of chlorine species, such as free chlorine and monochloramine, for the 
practical inactivation of Cryptosporidium. However, new data suggest 
that sequential disinfection with free chlorine followed by 
monochloramine can achieve a greater degree of Cryptosporidium 
inactivation than by chlorine alone. Moreover, ozone and chlorine 
dioxide have been found to be much more effective than chlorine. 
Sequential disinfection such as ozone or chlorine dioxide followed by 
one of the chlorine species appears more powerful than either 
disinfectant alone in inactivating Cryptosporidium. The following data 
detail the inactivation of Cryptosporidium by individual disinfectants, 
as well as by sequential disinfectants.
    The purpose of presenting this data in this section is to provide 
the public opportunity to comment on whether there is (a) sufficient 
information available for generating CT tables to estimate log 
inactivation of Cryptosporidium, comparable to what was done for 
Giardia under the SWTR, and (b) sufficient data to conclude that 
chlorination, at levels commonly practiced by utilities, is virtually 
ineffective for inactivating Cryptosporidium. Both of these issues 
relate to USEPA's rationale for using Giardia as the key target 
organism for defining the disinfection benchmark (see Section D).
    Table 11a summarizes the data on disinfection of Cryptosporidium 
with

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chlorine species and ultraviolet radiation (UV). The results from 
studies with free chlorine indicate that some inactivation of C. parvum 
could be achieved at relatively high doses of chlorine (i.e., >1,000 
mg/L of chlorine bleach and 80 mg/L of free chlorine) (Korich et al., 
1990a; Ransome et al., 1993) and a high CT value (7,200 mg-min/L) 
(Korich et al., 1990a; Lykins et al., 1992). However, this common water 
disinfectant has been conclusively shown to be ineffective for 
inactivation of C. parvum oocysts at practical plant doses (<6 mg 
Cl2/L) or CT values (Korich et al., 1990a; Ransome et al., 
1993; Finch et al., 1997). The same is essentially true for 
monochloramine (Lykins et al., 1992; Finch et al., 1997) and the 
oxidant of permanganate (Finch et al., 1997). Therefore, it is unlikely 
that significant inactivation of Cryptosporidium will occur in water 
treatment plants with the single addition of these disinfectants at 
currently used levels.

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    As indicated in Table 11a, the literature data on Cryptosporidium 
inactivation with UV appear controversial because of different 
experimental protocols used by different investigators. Finch et al. 
(1997) found that UV was ineffective in inactivating C. parvum 
suspended in a batch reactor. However, significant inactivation was 
observed when the oocysts were captured in 2cm filters and exposed to a 
preset UV irradiation dose (Campbell et al., 1995; Clancy et al., 
1997). More data are needed to evaluate the practical application of UV 
for inactivation of Cryptosporidium oocysts. Also, of interest are 
possible synergistic effects with UV application followed by residual 
disinfectants.
    Table 11b summarizes the findings of inactivation of 
Cryptosporidium with ozone. The data obtained from bench-scale tests 
with oxidant-demand-free laboratory water indicate that for CT values 
between 1.2-23.0 mg-min/L, the range of inactivation was 0.5 to 5 log 
at temperatures of 5 to 25  deg.C and at pH values of 7 to 8 (Peeters 
et al., 1989; Korich et al., 1990a,b; Parker et al., 1993; Ransome et 
al., 1993; Finch et al., 1994 & 1997). The variability demonstrated in 
these results is influenced by the differences in test procedures used 
by different researchers, i.e., the different measures of 
Cryptosporidium inactivation (infectivity, excystation, etc.) and the 
different methods of CT calculations (initial ozone dose, average ozone 
concentration, and ozone residual).
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    Therefore, caution should be used when comparing the results from 
one study to another. For instance, a CT value of 10 mg-min/L for 0.5-
log inactivation was obtained from the study conducted by Parker et al. 
(1993), who used vital dyes to evaluate the viability of 
Cryptosporidium. This result is incomparable to the data shown in Table 
11b. Subsequently, Korich et al. (1993) found that vital stains are of 
questionable value for determining oocyst viability.
    In another example, in a series of experiments at pH 7 and at 
temperatures of 5-22  deg.C, Finch et al. (1997) found a 45-92% 
reduction in ozone concentration at initial residuals of 0.6-2.2 mg/L 
and contact times of 5-15 minutes. Parker et al. (1993) reported that 
the Cryptosporidium inactivation level was greater when the ozone 
concentration was maintained at a constant level (i.e., through a batch 
mode reactor), compared to when the same initial ozone dose was allowed 
to decay during the same contact time. Both Finch et al. (1994) and 
Parker et al. (1993) found that an increase in temperature caused a 
higher inactivation at the same ozone residual and the same contact 
time. It appears that an increase of 15  deg.C decreases by half the CT 
values needed for a 2-log inactivation.
    Owens et al. (1994) observed that C. muris is slightly more 
resistant to ozone than C. parvum, and proposed that C. muris be used 
as a surrogate model for C. parvum. However, the data that support this 
hypothesis are very limited.
    Two pilot-scale studies with natural waters have been performed 
(Danial et al., 1993; Miltner et al., 1997). The CT values of ozone 
required to achieve 2- and 3-logs inactivation of Cryptosporidium were 
6.0 mg-min/L (pH 8, 24  deg.C) (Miltner et al., 1997) and 10-15 mg-min/
L (pH 7, 15  deg.C) (Danial et al., 1993). It appears that higher CT 
values are required in natural water for inactivation of 
Cryptosporidium than in laboratory water; this may be attributed to the 
existing oxidant demands in natural water or other factors. Danial et 
al. (1993) indicated that the ozone residual for a given dose rapidly 
decomposed as the pH was increased from 7 to 9 during lime addition. 
This finding implies that if ozonation is practiced in lime-softening 
water plants, it will be necessary to adjust the pH downstream.
    When inactivation of Cryptosporidium oocysts is compared with that 
of Giardia cysts with similar test protocols, C. parvum is 
approximately 10 times more resistant to ozone than G. lamblia in 
laboratory water (Finch et al., 1994) and G. muris in natural water 
(Owens et al., 1994; Miltner et al., 1997). These findings imply that 
the use of ozone cannot be expected to significantly inactivate 
Cryptosporidium at the concentration and contact times employed in 
inactivating Giardia in water treatment practices.
    Table 11c summarizes the findings of Cryptosporidium inactivation 
with chlorine dioxide. For CT values between 23-213 mg-min/L, the range 
of inactivation is 0.5-3.2 log or higher at temperatures of 10-25 
deg.C and at pH values of 7-8 in laboratory water (Peeters et al., 
1989; Korich et al., 1990b; Ransome et al., 1993; Finch et al., 1995 & 
1997). Similar to ozone, chlorine dioxide is also unstable in the 
water. In 0.05 M phosphate buffer water at pH 8 and 22  deg.C, Finch et 
al. (1997) found that a 49-99% reduction in chlorine dioxide 
concentrations occurs after 15-120 minutes at initial residuals of 
0.36-3.3 mg/L. LeChevallier et al. (1997b) recently performed a pilot-
scale study in a natural water by evaluating viability of oocysts with 
both an in-vitro excystation assay and a tissue culture infectivity. 
While the difference in results with the two methods was not shown, the 
study reported that a CT value of 40 mg-min/L results in 1-log 
inactivation of oocysts at pH 8.0 and 20 deg.C, and a 0.5-log 
inactivation at pH 6.0. The study also revealed that a temperature 
reduction from 20 to 10  deg.C decreases the effectiveness of chlorine 
dioxide by 40%.
    The existing data show chlorine dioxide as an effective 
disinfectant for Cryptosporidium inactivation. However, CT values 
required for Cryptosporidium inactivation appear much higher than those 
for same log inactivation of Giardia under comparable water conditions 
(Lisle and Rose, 1995). Since the 1994 D/DBP proposed rule has set the 
maximum contaminant levels for chlorine dioxide and chlorite (by-
product of chlorine dioxide), at 0.8 mg/L and 1 mg/L, respectively, the 
use of chlorine dioxide may be limited for the inactivation of 
Cryptosporidium.

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    Table 12 summarizes the results from Finch et al. (1997). Finch et 
al. found that sequential disinfection of C. parvum oocysts by 
different disinfectants is more effective than that indicated by the 
effectiveness of each disinfectant from independent studies, i.e., the 
effect is synergistic. According to their current report, greater than 
2.9-log inactivation of oocysts can be achieved when C. parvum is 
exposed to 0.75 mg/L initial ozone residual for 3.7 minutes and then 
2.0 mg/L free chlorine residual for 265 minutes (pH 6). Based on the 
additive effects of ozone and free chlorine alone under similar 
conditions, a 2.0-logs inactivation is expected. Similarly, the 
inactivation by monochloramine following ozonation is increased by 1.5 
log-units when compared with either ozone or monochloramine alone.
    Additional 1.2-log inactivation due to the synergism of chlorine 
dioxide and free chlorine has also been obtained at pH 8. Furthermore, 
sequential exposure of C. parvum oocysts to free chlorine followed by a 
monochloramine (pH 8.0) reduces infectivity by 0.6 log. Since the 
expected inactivation by either chlorine species at pH 8 is virtually 
zero, there is a synergism between free chlorine and monochloramine. It 
should be noted that combinations of chlorine species with other 
disinfectants may stimulate the formation of chlorate (Siddiqui et al., 
1996) or other toxic disinfectant byproducts. Also, the synergistic 
effect with sequential disinfectants has only been observed in bench-
scale studies in a single laboratory. Nevertheless, such findings 
suggest new strategies for the effective inactivation of 
Cryptosporidium. For a practical application, further investigations 
are being conducted at a wider range of water quality conditions (pH, 
temperature, and disinfectant demand) (USEPA, 1995b).

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    Analytical Method--Four analytical methods are currently being used 
to evaluate inactivation of Cryptosporidium oocysts: in vitro 
excystation, vital dyes (DAPI/PI staining), animal infectivity, and 
tissue culture infectivity. It has been shown that excystation and 
DAPI/PI staining consistently underestimate inactivation when compared 
with animal infectivity, which is more expensive (Finch et al., 1994; 
Black et al., 1996). The use of different animal models also leads to 
inconsistent results for Cryptosporidium infectivity. Although the 
tissue culture technique may provide a convenient, low-cost alternative 
to animal infectivity, only limited data exist with this method 
(LeChevallier et al., 1997b).
    Cryptosporidium Inactivation Map--In conjunction with development 
of the long-term ESWTR, USEPA is developing a graph of CT values versus 
log inactivation under various water quality conditions. The Agency is 
also exploring other means that utilities can use to estimate 
Cryptosporidium inactivation with different single or sequential 
disinfectants. Additional data, especially under natural water/field 
conditions, is necessary to develop this graph. Finch et al. (1994) 
attempted to establish CT tables for Cryptosporidium inactivation with 
ozone by analyzing numerous sets of experimental data by using both the 
Chick-Watson model and the Hom model. It was found that the 
inactivation kinetics of C. parvum by ozone deviated from the simple 
first-order Chick-Watson model and was better described by a nonlinear 
Hom model. A further analysis, however, hasn't been performed on a 
broader data basis to evaluate such a finding. Moreover, a much better 
understanding of Cryptosporidium inactivation with sequential 
disinfectants is needed.
3. New Virus Inactivation Studies
    One of the treatment options that USEPA proposed as part of the 
ESWTR was to include a 4-logs minimal inactivation requirement for 
viruses, in addition to any physical removal of viruses that might be 
achieved. USEPA intends to consider this option when additional data 
become available. However, significant data are available regarding 
disinfection conditions necessary to achieve different inactivation 
levels of viruses. The availability of such data is discussed below.
    USEPA's guidance manual to the SWTR (USEPA, 1991a), assumes that CT 
values for chlorine necessary to achieve a 0.5-log inactivation of 
Giardia cysts will result in greater than a 4-log inactivation of 
viruses. This assumption is based on the comparison between the effects 
of free chlorine on Giardia lamblia and hepatitis A virus (HAV). In the 
proposed ESWTR, USEPA noted that some viruses are more resistant to 
chlorine than is HAV, and the use of disinfectants other than free 
chlorine to achieve 0.5-log inactivation of Giardia may not yield a 4-
log inactivation of viruses. Achieving adequate inactivation of viruses 
may be of greater concern when disinfectants other than chlorine (e.g., 
chlorine dioxide and ozone) are used to inactivate Cryptosporidium 
oocysts.
    CT tables in the SWTR for estimating viral inactivation efficiency 
with chlorine dioxide and ozone were based on laboratory studies using 
HAV and poliovirus 1, respectively. Very few studies have since been 
conducted to investigate viral inactivation with chlorine dioxide. 
Huang et al. (1997) evaluated the disinfection effects of chlorine 
dioxide on six viruses, including poliovirus type 1, coxsackievirus 
type B3, echovirus 11, adenovirus type 7, herpes simplex 
virus 1, and mumps virus. All viruses were completely inactivated at 
CT=90 mg-min/L (3 mg/L of initial dose and 30 minutes of contact time) 
at pH values of 3, 5, and 7, but not 9. Complete inactivation of all 
six viruses was also found at CT=30 mg-min/L (1 mg/L of initial dose 
and 30 minutes of contact time) at pH 7.0. At 7.0 mg/L of initial dose, 
greater than 10 minutes of contact time were required for complete 
inactivation at the same pH.
    More studies have been performed to evaluate viral inactivation 
efficiencies by ozone than by chlorine dioxide. The results from these 
studies are summarized in Table 13.

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    In general, the tested viruses, including HAV, MS2 coliphage, 
poliovirus 1 (PV1), poliovirus 3 (PV3), and T2 phage, are relatively 
sensitive to ozone, and more than 4-logs inactivation of these viruses 
can be achieved with less than 2 mg/L of ozone and 5 minutes of contact 
time in a wide range of pH values and temperatures (Herbold et al., 
1989; Kaneko, 1989; Vaughn et al., 1990; Finch et al., 1992; Hall and 
Sobsey, 1993; Miltner et al., 1997). Finch et al. (1992) reported that 
MS2 coliphage was extremely sensitive to ozone in both laboratory water 
and natural water, and that complete viral inactivation could occur 
during the process of satisfying ozone demand in natural water. In 
paired experiments, they also found that there was significantly less 
inactivation of PV3 than MS2 coliphage under the same ozonation 
conditions. In contrast, Hall and Sobsey (1993) demonstrated that MS2 
coliphage was at least as resistant to ozone as HAV in a pH range of 6-
10, suggesting that MS2 coliphage might be a good model for predicting 
HAV inactivation by ozone. In a continuous-flow system with a constant 
flow of ozone and viral suspensions, Herbold et al. (1993) found that 
HAV required approximately three times the ozone that PV1 required for 
the same inactivation. In a similar system, Botzenhart et al. (1993) 
showed that MS2 coliphage was more resistant to ozone than PhiX 174 
coliphage.
    Some researchers have pointed out that viral disinfection with 
ozone is difficult to evaluate, not only due to the relatively short 
inactivation times, but also because the concentration of ozone 
significantly decreases during the contact time. Finch et al. (1992) 
found ozone dose and the interaction between ozone dose and dissolved 
organic carbon (DOC) were the most important factors affecting ozone 
inactivation of MS2 coliphage in surface waters. Inactivation of MS2 
coliphage was significantly reduced when the natural DOC in the water 
increased during spring runoff, presumably because the ozone 
concentration was rapidly depleted by the DOC. This effect, however, 
was not observed when an ozone residual of 0.1 mg/L at the end of 30 
seconds was detected, resulting in greater than 4-logs inactivation of 
MS2 coliphage under all water quality conditions.
    Finch et al. (1992) found that the effects of temperature and 
turbidity on inactivation rates were indistinguishable from 
experimental error. This contrasts with other studies that reported 
that viral inactivation with ozone was more efficient at lower 
temperatures (Botzenhart et al., 1993; Herbold et al., 1993), and the 
presence of kaolin particles at 1 mg/L or higher resulted in a greater 
level of ozone residual required for the same level of viral 
inactivation (Kaneko, 1989). Vaughn et al. (1990) observed that the pH-
related effects on ozonation of viruses was not significant in a pH 
range of 6-8. Kaneko (1989) reported that the presence of ammonium 
decreased the ozone concentration and thus decreased the inactivation 
efficiency of ozone.
    Kaneko (1989) also revealed that ozonation of viruses could be 
divided into three phases: an initial large reduction of viruses; a 
subsequent logarithmic reduction of viruses; and finally, a slow 
reduction in response to decreasing ozone concentrations. Thus, it is 
not surprising that the viral inactivation rate beginning 5 minutes 
after adding the disinfectant was greater with chlorine than with 
ozone, even though the inactivation rates within 5 minutes of the 
addition of ozone were 10 to 1,000 higher than the initial rates of 
inactivation with chlorine (Kaneko and Igarashi, 1983; Kaneko, 1989).
    Finch et al. (1992) have concluded that, when comparing the ozone 
inactivation data for MS2 coliphage, PV3, and Giardia muris, the 
conditions for inactivating G. muris cysts are the most rigorous and it 
is likely that enteric viruses will be inactivated by greater than 4 
logs when Giardia is inactivated by 3 logs. Such a comparison is also 
needed for chlorine dioxide. Although the tested enteric viruses appear 
to be more susceptible to ozone than Giardia, no data are yet available 
on the effectiveness of ozone in inactivating Norwalk virus and other 
pathogenic human viruses, especially when they are clumped and adsorbed 
to organic matter as they usually are in natural water. The varying 
results on viral inactivation with ozone suggest that ozone 
inactivation studies need to measure and report ozone concentrations 
over time.

III. Economic Analysis of the M-DBP Advisory Committee 
Recommendations

A. Overview of RIA for Proposed Rule

    The Regulatory Impact Analysis (RIA) for the proposed IESWTR (59 FR 
38832, July 29, 1994), estimated national capital and annualized costs 
(amortized capital and annual operating costs) for surface water 
systems serving at least 10,000 people at $3.6 billion and $391 million 
respectively. These costs were based on the assumption that systems 
would also be required to provide enough treatment to achieve less than 
a 10-4 risk level from giardiasis while meeting the Stage 1 
DBPR. In estimating these costs, it was assumed that additional Giardia 
reduction beyond the requirements of the SWTR to achieve the 
10-4 risk level would be achieved solely by using chlorine 
as the disinfectant and providing additional contact time by increasing 
the disinfectant contact basin size.
    The Regulatory Impact Analysis for the Interim Enhanced Surface 
Water Treatment Rule (USEPA, 1994d) predicted that ESWTR compliance 
would result in no more than a few hundred infections caused by 
waterborne Giardia per year per 100 million people. This is hundreds of 
thousands of cases fewer than predicted in the absence of an ESWTR. 
USEPA estimated that the benefit per Giardia infection avoided would be 
$3000 per case. Using this estimate, the 400,000 to 500,000 Giardia 
infections per year that could be avoided would have an economic value 
of $1.2 to $1.5 billion per year. This suggests that the benefit 
nationwide of avoiding Giardia infections is as much as three or four 
times greater than the estimated $391 million national annual cost of 
providing additional contact time.
    Table 14 shows this $391 million estimated cost as described in the 
proposal (using 1992 $s and a discount rate of 10 percent). The table 
also converts this cost to 1997$s (with a 10 percent discount rate) to 
provide for comparison with costs based on provisions included in this 
notice.
    For a more detailed discussion of the cost and benefit analysis of 
the 1994 proposal refer to The Regulatory Impact Analysis for the 
Interim Enhanced Surface Water Treatment Rule (USEPA, 1994d).

B. What's Changed Since the Proposed Rule

    The cost estimates in the proposed rule reflect cost estimates for 
one of several regulatory alternatives included in the proposal. At the 
time of proposal USEPA assumed that additional data would be collected 
under the ICR to more accurately estimate costs and benefits of the 
Giardia based rule option as well as alternative regulatory options. 
National source water occurrence data for Giardia and Cryptosporidium 
are being collected as part of the ICR to help this effort. Due to the 
delays discussed earlier in this Notice and the new expedited rule 
deadlines, ICR data will not be available for the IESWTR impact 
analysis. From February 1997, however, the Agency has worked with 
stakeholders to identify additional data available since 1994 to be 
used in developing components of the

[[Page 59545]]

expedited rules. USEPA established the Microbial and Disinfectants/
Disinfection Byproducts Advisory Committee to collect, share and 
analyze new information and data, as well as to build consensus on the 
regulatory implications of this new information. The Committee met five 
times from March to July, 1997 to discuss issues related to the IESWTR 
and Stage I D/DBPR.
    USEPA has also evaluated comments received on the proposal in its 
consideration of elements to be included in a regulatory option 
independent of ICR source water occurrence data. These comments 
suggested (1) sufficient degrees of effectiveness of current treatment, 
including filtration, in preventing waterborne transmission of 
Cryptosporidium and (2) a revised approach focussing on optimizing 
treatment processes. In response to these comments, new information 
received and the Advisory Committee's recommendations, USEPA has 
developed the Economic Analysis described in summary below. Details of 
the analysis used to derive the costs and benefits described below are 
available in the draft document Economic Analysis of M/DBP Advisory 
Committee Recommendations for the Interim Enhanced Surface Water 
Treatment Rule (USEPA, 1997a). The economic analyses are based on the 
Committee's recommendations to USEPA on issues including turbidity 
control, removal of Cryptosporidium, disinfection benchmarking and 
sanitary surveys.

C. Summary of Cost Analysis

1. Total National Costs
    USEPA is considering several approaches, based on the 
recommendations of the Advisory Committee. The two most substantial 
approaches, from the perspective of costs and benefits, govern 
turbidity performance and turbidity monitoring. The Microbial and 
Disinfectants/Disinfection Byproducts Committee made a number of 
recommendations that are indicated in this Notice for comment, 
including new turbidity provisions with associated monitoring 
requirements, disinfection benchmarking practices to help ensure there 
are no significant increases in microbial risk while systems comply 
with the Stage 1 DBPR and a sanitary survey provision of relatively 
minimal costs. USEPA estimates that the national capital and annualized 
costs (amortized capital and annual operating costs) of these 
provisions (based on a 10 percent interest rate) would be $730 million 
and $312 million, respectively [Table 14] (USEPA, 1997a). These figures 
include costs associated with improved treatment, turbidity monitoring, 
a disinfection benchmark and sanitary surveys. This represents a 
reduction of over $3.4 billion (in 1997 $s) from the capital costs 
estimated for the proposed rule. This is accounted for primarily by the 
recommendations for changes in the level of disinfection required and 
restoration of disinfection credit prior to precursor removal. This 
would result in fewer systems needing to install additional 
disinfectant contact basins, relative to the costs in the 1994 
proposal.
    A discount rate of 10 percent was used to calculate the unit costs 
for the national cost model. This discount rate provides both a link to 
the 1994 IESWTR cost analyses and is a reasonable estimation of the 
cost to utilities to finance capital purchases assumed to be necessary 
due to the proposal.
    In order to demonstrate the sensitivity of the national cost model 
to different discount rates, the national costs at 10 percent are 
compared to national costs calculated using a 7% discount rate. This 
rate represents the standard social discount rate preferred by the 
Office of Management and Budget for benefit-cost analyses of government 
programs and regulations. Tables of unit cost estimates at the 7 
percent rate are included in the appendix to the draft Economic 
Analysis and displayed for comparative purposes (USEPA, 1997a). Costs 
presented in the Economic Analysis are expressed in June 1997 constant 
dollars.
    The water flow rates that were used in calculating the costs of the 
1994 proposal (in 1992 $s and 1997 $s) were also used in calculating 
the national costs of the recommended provisions discussed in this 
Notice. Additional analyses gauged the sensitivity of the cost model to 
a different input value for maximum flow rates for the largest system 
category (systems serving >1 million people). With this adjusted flow 
rate (using a 10 percent discount rate) total annualized national costs 
would be $314 million, compared to $312 million based on flow rates 
used in the 1994 proposal.
    USEPA requests comment on how the new data have been used and any 
additional data that would improve the assessment of costs and 
benefits.

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[[Page 59547]]

2. Household Costs
    Household costs are a way to represent water system treatment costs 
as a costs to the system customer. Figure 14 displays results of the 
household cost analyses for a 0.3 NTU, 1 maximum CFE NTU turbidity 
treatment approach discussed in this Notice. As can be seen from the 
graph, a small percentage of the systems might, using this methodology, 
incur a maximum cost per household of approximately $110 per year. The 
highest household costs are incurred in households served by small 
systems that need to implement all of the activities to comply.
    It must be borne in mind that the upper bound of the graph displays 
an extrapolated curve, and does not represent actual data points. The 
assumptions and structure of this analysis, in describing the curve, 
tend to overestimate the highest costs. To find itself on the upper 
bound of the curve, a system would have to implement all, or almost 
all, of the treatment activities. These systems, conversely, might seek 
less costly alternatives, such as connecting into a larger regional 
water system. In the judgment of the Advisory Committee's Technical 
Work Group, this extreme situation and the resulting high values may 
occur only for a small number of households.
    Based on this analysis, over 97 percent of the households are 
estimated to incur annual costs of less than $20 per household per year 
and over 50 percent are estimated to incur costs of less than $2 per 
household per year.

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D. Cost of Turbidity Performance Criteria and Associated Monitoring

1. System Level Impact Analysis
    The TWG developed a list of treatment activities that systems would 
be expected to employ in order to implement Advisory Committee 
recommendations. These activities were grouped into 10 categories based 
on general process descriptions as follows; chemical addition, 
coagulant improvements, rapid mixing, flocculation improvements, 
settling improvements, filtration improvements, hydraulic improvements, 
administration culture improvements, laboratory modifications and 
process control testing modifications. Descriptions of how systems were 
expected to evaluate these activities are described in the draft 
document Technologies and Costs for the Interim Enhanced Surface Water 
Treatment Rule (USEPA, 1997b).
2. National Impact Analyses
    a. Decision Tree. The decision tree is a table of treatment 
activities that taken either singly or in combination will help 
utilities evaluate what is potentially involved in meeting the 
turbidity limits recommended by the Advisory Committee, i.e., the 
requirement that utilities serving more than 10,000 people be required 
to achieve a 95 percentile turbidity limit of 0.3 NTU and at no time 
exceed a turbidity value of 1 NTU (Appendix A, USEPA, 1997a). 
Percentages in a decision tree represent the projected percentage of 
public water systems using that activity to meet the turbidity limits 
recommended by the Advisory Committee. These percentages were factors 
in the national cost model

[[Page 59548]]

and generally represent the percentage of systems needing to modify 
treatment to meet the limits.
    Further description of the compliance decision tree and methodology 
are included in the draft Economic Analysis of M/DBP Advisory Committee 
Recommendations for the Interim Enhanced Surface Water Treatment Rule 
(Economic Analysis) (USEPA, 1997a).
    b. Utility Costs. Turbidity Treatment. The number of systems, the 
associated total capital costs, and the associated total annualized 
costs were estimated for seven system size categories. Total annual 
costs were calculated for each possible treatment activity and for each 
system size category. Unit costs were converted to annualized cost 
totals (in thousands of dollars) using the methodology described in the 
draft Economic Analysis.
    As indicated in Table 14, the estimate of national annualized 
turbidity treatment costs are $203 million based on the Advisory 
Committee's recommended 0.3 NTU 95th percentile CFE standard while 
meeting a 1 NTU maximum combined filter effluent level (calculated with 
a 10% interest rate in 1997$s).
    Turbidity Monitoring. A generalized turbidity monitoring model was 
developed to provide a framework for estimating costs associated with 
individual filter monitoring. The model assumes turbidimeters for each 
filter and an on-line Supervisory Control And Data Acquisition (SCADA) 
system. Filter readings would be taken at least once every 15 minutes 
and tabulated. The model assumes that once each work shift (8 hours) 
the turbidity data would be converted to a reviewable form, and would 
then be reviewed by a system manager. In cases where the monitoring 
recorded exceedances as described below, a report would be made to the 
State and, if warranted, an individual filter review or system 
assessment might occur. Annual utility monitoring costs are estimated 
at $96 million as shown in Table 14 above.
    Under the approach recommended by the Advisory Committee, exception 
reporting to the State is warranted if:

--An individual filter has a turbidity level greater than 1.0 NTU for 2 
consecutive measurements 15 minutes apart.
--An individual filter has a turbidity level greater than 0.5 NTU at 
the end of the first 4 hours of filter operation for 2 consecutive 
measurements 15 minutes apart.
--If a plant reports exceedances of 1.0 NTU at one filter for 3 
consecutive months, an individual filter assessment (IFA) is required 
to be performed by the utility.
--If a plant records exceedances of 2.0 NTU at one filter in 2 
consecutive months, a comprehensive performance evaluation (CPE) is 
required and must be performed by a third party.

    c. State Costs. Annual Review Costs. Under the recommended 
provisions, it would be the State's responsibility to review system 
data to ensure that all systems in the State are in compliance with the 
provisions. State activities include compliance tracking, review of 
Statewide utility data, record keeping, and compliance determinations. 
Annual State costs for review (nationwide) are estimated to be $5.3 
million (USEPA, 1997a).
    Implementation and Start-Up Costs Related to Turbidity Monitoring. 
One-time State implementation activities include the adoption of the 
rule and State regulation development. As shown in Table 14, the rule 
would collectively cost States a total of $407,000 to implement 
turbidity monitoring provisions.
    Exception Costs (Exception Reports, IFAs and CPEs). Under the 
approach recommended by the Advisory Committee, a monthly exception 
report would be filed by each utility at which a plant exceeds 
individual filter effluent (IFE) turbidities of either 1.0 NTU for 2 
consecutive measurements 15 minutes apart, or 0.5 NTU at the end of the 
first 4 hours of a filter run.
    In addition to the monthly exception report of individual filter 
effluent exceedances, additional steps are triggered when exceedances 
persist. If an individual filter has turbidity levels greater than 1.0 
NTU based on 2 consecutive measurements fifteen minutes apart at any 
time in each of 3 consecutive months, the system conducts a self 
assessment of the filter utilizing as guidance relevant portions of 
guidance issued by the Environmental Protection Agency for 
Comprehensive Performance Evaluation (CPE). If an individual filter has 
turbidity levels greater than 2.0 NTU based on 2 consecutive 
measurements fifteen minutes apart at any time in each of two 
consecutive months, the system will arrange for the conduct of a CPE by 
the State or a third party approved by the State.
    The following assumptions were made by the Technical Working Group 
of the Advisory Committee regarding the percentage of systems per year 
that would trigger an interaction with the State based on the 
recommended provisions.

--10 percent of systems per year are assumed to file monthly reports to 
the State based on individual filter effluent provisions
--2 percent of systems per year are assumed to trigger Individual 
Filter Assessment (IFA) provisions
--1 percent of systems per year are assumed to trigger Comprehensive 
Performance Evaluation (CPE) provisions.

    Based on these assumptions, approximately 28 IFAs and 14 CPEs will 
be conducted each year at an estimated cost of $5,000 and $25,000 each, 
respectively. States are expected, therefore, to incur annual costs 
(nationally) of $64,000 to review the exception reports, $138,000 and 
$345,300 in annual costs for IFAs and CPEs, respectively. The combined 
total annual State cost for these items is $572,000 (Table 14, above).

E. Disinfection Benchmark

1. Decision Tree
    The Advisory Committee recommended that a utility prepare a 
disinfection profile if they:

--measure TTHM levels of at least 80 percent of the MCL (0.064 mg/l) as 
an annual average for the most recent 12-month period for which 
compliance data are available.
--measure HAA% level of at least 80 percent of the MCL (0.048 mg/l) as 
an annual average for the most recent 12-month compliance period for 
which compliance data are available.

    HAA and TTHM figures from the 1996 Water Industry Data Base (WIDB) 
were used to estimate the percentage of systems that would be required 
to prepare a disinfection profile.
2. Utility Costs
    Utility costs associated with profiling were divided into four 
activity areas; cost per system, cost per plant using paper data (i.e., 
for those plants that currently use paper to document their plant 
profile data), cost per plant using mainframe data, and cost per plant 
using PC data. Plants with paper data were assumed to represent half of 
the number of plants needing profiling, while plants with mainframe 
data and plants with PC data each represent 25 percent of all plants. 
The TWG assumed that all plants currently collect this data in either 
an electronic or paper format, and, therefore, would not incur 
additional data collection expenses due to microbial profiling. Data 
reporting costs per plant that are associated with microbial profiling 
include; data entry and spreadsheet development, data manipulation and 
analysis, and data

[[Page 59549]]

review. Costs per system include those to; read and understand the 
rule, mobilization and planning, generation of reports to State and for 
in-house review, and meet and review profile with the State. The 
national costs associated with microbial profiling for utilities was 
estimated at $2.7 million [Table 14].
3. State Costs
    States will review profiles as part of its sanitary survey process. 
Utilities required to develop a disinfection profile that subsequently 
decide to make a significant change in disinfection practice must 
consult with the state prior to making such a change. Table 14 details 
the total national State costs of profiling (one-time) at $3.1 million.

F. Sanitary Surveys

    States are expected to conduct sanitary surveys on a rotating 
basis, in general no less frequently than once every 3 years for 
community water systems (CWSs) and no less frequently than every 5 
years for noncommunity water systems (NCWSs). For this analysis, 80 
percent of Systems are assumed to have already conducted a sanitary 
survey. The remaining 20 percent of systems are considered to require 
new surveys in order to comply with the requirements in the IESWTR. The 
total national cost estimate for sanitary surveys, as shown in Table 
14, is estimated at $6.7 million.

G. Summary of Benefits Analysis

    The economic benefits of the provisions recommended by the Advisory 
Committee derive from the increased level of protection to public 
health. The primary goal of these provisions is to improve public 
health by increasing the level of protection from exposure to 
Cryptosporidium and other pathogens in drinking water supplies through 
improvements in filtration at water systems. In this case, benefits 
will accrue due to the decreased likelihood of endemic incidences of 
cryptosporidiosis, giardiasis and other waterborne disease, and the 
avoidance of resulting health costs. In addition to reducing the 
endemic disease, the provisions are expected to reduce the likelihood 
of the occurrence of Cryptosporidium outbreaks and their associated 
economic costs, by providing a larger margin of safety against such 
outbreaks for some systems.
    The benefits analysis quantitatively examines health damages 
avoided based on the provisions recommended by the Advisory Committee. 
The assessment also discusses, but does not quantify, other economic 
benefits that may result from the provisions, including reduced risk of 
outbreaks, avoided costs of averting behavior such as boiling water.
    The assessment of net benefits is always somewhat problematic due 
to the relative ease of quantifying compliance treatment costs versus 
the difficulty of assigning monetary values to the avoidance of health 
damages and other benefits arising from a regulation. The challenge of 
assessing net benefits for the recommended provisions is compounded by 
the fact that there are large areas of scientific uncertainty regarding 
the exposure to and the risk assessment for Cryptosporidium. Areas 
where important sources of uncertainty enter the benefits assessment 
include the following.
     Occurrence of Cryptosporidium oocysts in source waters.
     Occurrence of Cryptosporidium oocysts in finished waters.
     Reduction of Cryptosporidium oocysts due to treatment, 
including filtration and disinfection.
     Viability of Cryptosporidium oocysts after treatment.
     Infectivity of Cryptosporidium.
     Incidence of infections and associated symptomatic 
response (including impact of under reporting).
     Characterization of the risk.
     Willingness to pay to reduce risk and avoid costs.
    The cumulative impact of these uncertainties on the outcome of the 
exposure and risk assessment is impossible to measure. The benefit 
analysis attempts to take into account some of these uncertainties by 
estimating benefits under two different current treatment assumptions 
and three improved removal assumptions. The benefit analysis also used 
Monte Carlo simulations to derive a distribution of estimates, rather 
than a single point estimate.
    The following two assumptions were made about the performance of 
current treatment in removing or inactivating oocysts to estimate 
finished water Cryptosporidium concentrations. The standard assumption 
is that current treatment results in a mean physical removal and 
inactivation of oocysts of 2.5 logs and a standard deviation 
0.63 logs). Because the finished water concentrations of 
oocysts represent the baseline against which improved removal from the 
recommended provisions is compared, variations in the log removal 
assumption could have considerable impact on the risk assessment. To 
evaluate the impact of the removal assumptions on the baseline and 
resulting improvements, an alternative mean log removal/inactivation 
assumption of 3.0 logs (and a standard deviation 0.63 logs) 
was also used to calculate finished water concentrations of 
Cryptosporidium.
    USEPA made three assumptions about the improved log removal of 
oocysts that would result from the turbidity provisions recommended by 
the Advisory Committee. These were based on studies of treatment 
removal efficiencies discussed earlier in this Notice (Table 1: 
Cryptosporidium and Giardia lamblia removal efficiencies by rapid 
granular filtration). A range of 2-6 logs removal of Cryptosporidium 
oocysts were observed in these studies. USEPA 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.
    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, 
as described above, i.e., that sites currently achieving the highest 
filtered water turbidity performance 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 15 contains the 
assumptions used to generate the new treatment distribution.

                 Table 15.--Improved Removal Assumptions                
------------------------------------------------------------------------
          Additional log removal with committee recommendations         
-------------------------------------------------------------------------
                                      Low           Mid          High   
------------------------------------------------------------------------
Plants now meeting 0.2 NTU                                              
 limit.........................       None          None            None
Plants operating between 0.2-                                           
 0.3 NTU.......................          0.15          0.25          0.3
Plants now meeting 0.4 NTU                                              
 limit.........................          0.35          0.5           0.6

[[Page 59550]]

                                                                        
Plants now failing to meet 0.4                                          
 NTU limit.....................          0.5           0.75          0.9
------------------------------------------------------------------------

    The TWG working group assumed that for plants to achieve a 0.3 NTU 
95th percentile standard they would operate their plants to achieve a 
0.2 NTU limit. Therefore, systems meeting a 95th percentile limit of 
0.2 NTU were assumed to make no further treatment changes to meet a 0.3 
NTU standard, and therefore show no incremental increase in log 
removal.
    Given the uncertainties described above, assumptions were made in 
developing the risk characterization. In summary, USEPA assumed:

--an exponential dose/response function for estimating infection rates 
(Haas et al., 1996)
--2 liters per person daily water consumption with a log normal 
distribution (Haas and Rose, 1995)
--a national surface water distribution of oocysts based on Monte Carlo 
analysis of data collected by LeChevallier and Norton (USEPA, 1996a)
--A uniform distribution of percentage of oocysts that would be 
infectious with a mean value of 10 percent
--An estimated 0.39 mean ratio (triangular distribution) of people that 
are infected to people that become ill (Haas, et al., 1996).
--The cost of an avoided case of cryptosporidiosis was estimated to be 
approximately $1800 per case. This was extrapolated from the estimate 
of $3,000 for giardiasis used in the RIA for the proposal, and based on 
the relatively shorter average length of illness.

    Risk characterization uses these assumptions to calculate the 
number of illnesses avoided in Table 16. Using this number of illnesses 
avoided, the cost of illnesses avoided is calculated under each current 
log treatment assumption (i.e., 2.5 and 3.0 logs) for each of the 
improved removal assumptions. Table 16 summarizes the mean expected 
value of potential benefits expected to accrue to the recommended 
provisions under the six different scenarios, as well as the range.

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[[Page 59552]]

IV. National Technology Transfer and Advancement Act

    Under section 12(d) of the National Technology Transfer and 
Advancement Act (``NTTAA''), the Agency is required 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, 
etc.) that are developed or adopted by voluntary consensus standards 
bodies. Where available and potentially applicable voluntary consensus 
standards are not used by EPA, the Act requires the Agency to provide 
Congress, through the Office of Management and Budget, an explanation 
of the reasons for not using such standards.
    The Agency does not believe that this Notice addresses any 
technical standards subject to the NTTAA. A commenter who disagrees 
with this conclusion should indicate how the Notice is subject to the 
Act and identify any potentially applicable voluntary consensus 
standards.

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82. Massachusetts Department of Environmental Protection. [Rapacz MV 
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93. Ongerth JE and JP Pecoraro (1995). Removing Cryptosporidium 
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108. Schulmeyer PM (1995). Effect of the Cedar River on the Quality 
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109. Sethi V, P Patnaik, P Biswas, RM Clark, and EW Rice (1997). 
Evaluation of Optical Detection Methods for Waterborne Suspensions. 
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110. Siddiqui MS (1996). Chlorine-ozone interactions: Formation of 
chlorate. Water Research, 30(9): 2160-2170.
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particulate matter, algae, and bacteria in an uncovered, finished-
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112. Smith HV, RWA Girdwood, WJ Patterson, et al. (1988). Waterborne 
outbreak of cryptosporidiosis. Lancet 2: 1484.
113. Solo-Gabriele H and S Neumeister (1996). U.S. Outbreaks of 
Cryptosporidiosis. Journal AWWA (Sept 1996), 88: 76-86.
114. Sonoma County Water Agency (1991) Russian River Demonstration 
Study (unpublished report) and Letter from Bruce H. Burton, P.E., 
District Engineer, Santa Rosa District Office to Robert F. Beach, 
General Manager Sonoma County Water Agency.
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(1992). Method 2130B.
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Cryptosporidium by slow sand filtration. Wat Sci Tech, 31(5-6): 81-
84.
117. USEPA (1979). National Interim Primary Drinking Water 
Regulations; Control of Trihalomethanes in Drinking Water. 44 FR 
68624, November 29, 1979.
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Legionella, and Heterotrophic Bacteria; Final Rule. 54 FR 27544, 
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127. USEPA (1994b). National Primary Drinking Water Regulations: 
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of Ozone Treatment on the Infectivity of Hepatitis A Virus. 1990. 
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Gerba (1994). Evaluation of Cryptosporidium Removal through High-
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    Dated: October 22, 1997.
Robert Perciasepe,
Assistant Administrator.

Appendix A--U.S. Environmental Protection Agency, Microbial/
Disinfection by-Products (M/DBP), Federal Advisory Committee

Agreement in Principle

1.0  Introduction

    Pursuant to requirements under the Safe Drinking Water Act 
(SDWA), the Environmental Protection Agency (EPA) is developing 
interrelated regulations to control microbial pathogens and 
disinfectants/disinfection byproducts (D/DBPs) in drinking water. 
These rules are collectively known as the microbial/disinfection 
byproducts (M/DBP) rules.
    The regulations are intended to address complex risk trade-offs 
between the two different types of contaminants. In keeping with the 
agreement reached during the 1992-93 negotiated rulemaking on these 
matters, EPA issued a Notice of Proposed Rulemaking for Disinfection 
By-Products Stage I on July 29, 1994. EPA also issued a Notice of 
Proposed Rulemaking for an Interim Enhanced Surface Water Treatment 
Rule (IESWTR) on July 29, 1994. Finally, in May 1996, EPA 
promulgated a final Information Collection Rule (ICR), to obtain 
data on source water quality, byproduct formation and drinking water 
treatment plant design and operations.
    As part of recent amendments to the SDWA, Congress has 
established deadlines for all the M/DBP rules, beginning with a 
November 1998 deadline for promulgation of both the IESWTR and the 
Stage I D/DBP Rule. To meet this new deadline, EPA initiated an 
expedited schedule for development of these two rules. Building on 
the 1994 proposals, EPA intends to issue a Notice of Data 
Availability (NODA) in November 1997 for public comment. EPA also 
decided to establish a committee under the Federal Advisory 
Committee Act (FACA) for development of the rules.
    The M/DBP Advisory Committee is made up of organizational 
members (parties) named by EPA (see Attachment A). The immediate 
task of the Committee has been to discuss, evaluate and provide 
advice on data, analysis and approaches to be included in the NODA 
to be published in November 1997. This Committee met four times from 
March through June 1997, with the initial objective to reach 
consensus, where possible, on the elements to be contained in the D/
DBP Stage I and IESWTR NODA. Where consensus was not reached, the 
Committee sought to develop options and/or to clarify key issues and 
areas of agreement and disagreement. This document is the 
Committee's statement on the points of agreement reached.

2.0  Agreement in Principle

    The Microbial and Disinfection By-Products Federal Advisory 
Committee considered the technical and policy issues involved in 
developing a DBP Stage I rule and an IESWTR under the Safe Drinking 
Water Act and recommends that the Environmental Protection Agency 
base the applicable sections of its anticipated M/DBP Notice of Data 
Availability (NODA) on the elements of agreement described below.
    This agreement in principle represents the consensus of the 
parties on the best conceptual principles that the Committee was 
able to generate within the allocated time and resources available.
    The USEPA, a party to the negotiations, agrees that:
    1. The person signing this agreement is authorized to commit 
this party to its terms.
    2. EPA agrees to hold a meeting in July 1997 following 
circulation of a second draft of the NODA to obtain comments from 
the parties and the public on the extent to which the applicable 
sections of the draft NODA are consistent with the agreements below.
    3. Each party and individual signatory that submits comments on 
the NODA agrees to support those components of the NODA that reflect 
the agreements set forth below. Each party and individual signatory 
reserves the right to comment, as individuals or on behalf of the 
organization he or she represents, on any other aspect of the Notice 
of Data Availability.
    4. EPA will consider all relevant comments submitted concerning 
the Notice(s) of Proposed Rulemaking and in response to such 
comments will make such modifications in the proposed rule(s) and 
preamble(s) as EPA determines are appropriate when issuing a final 
rule.
    5. Recognizing that under the Appointments Clause of the 
Constitution governmental authority may be exercised only by 
officers of the United States and recognizing that it is EPA's 
responsibility to issue final rules, EPA intends to issue final 
rules that are based on the provisions of the Safe Drinking Water 
Act, pertinent facts, and comments received from the public.
    6. Each party agrees not to take any action to inhibit the 
adoption of final rule(s) to the extent it and corresponding 
preamble(s) have the same substance and effect as the elements of 
this agreement in principle.

[[Page 59556]]

2.1  MCLs

    MCLs should remain at the levels proposed: 0.080 mg/l for TTHMs, 
0.060 mg/l for HAA5, and 0.010 mg/l for bromate.

2.2  Enhanced Coagulation

    The proposed enhanced coagulation provisions should be revised 
as follows:
    a. The top row of the TOC removal table (3x3 matrix) should be 
modified for systems that practice enhanced coagulation by lowering 
the TOC removal percentages by 5% across the top row, while leaving 
the other rows the same.
    b. SUVA (specific UV absorbance) should be used for determining 
whether systems would be required to use enhanced coagulation. The 
use of a raw water SUVA < 2.0 liter/mg-m as a criterion for not 
requiring a system to practice enhanced coagulation should be added 
to those proposed in Sec. 141.135(a)(1)(i)-(iv).
    c. For a system required to practice enhanced coagulation or 
enhanced softening, the use of a finished water SUVA < 2.0 liter/mg-
m should be added as a Step 2 procedure. Such a criterion would be 
in addition to the proposed Step 2 procedure, not in lieu of it.
    d. The proposed TOC removals for softening systems should be 
modified by lowering the value for TOC removal in the matrix at 
alkalinity >120 mg/l and TOC between 2-4 mg/l by 5% (which would 
make it equal to the value for non-softening systems) and leaving 
the remaining values as proposed.
    e. If a system is required to practice enhanced softening, lime 
softening plants would not be required to perform lime soda 
softening or to lower alkalinity below 40-60 mg/l as part of any 
Step 2 procedure.
    f. There is no need to separately address softening systems in 
the 3x3 matrix or the Step 1 regulatory language, which was 
identical to enhanced coagulation regulatory language in the 
proposed D/DBPR. The revised matrix should appear as follows:

------------------------------------------------------------------------
                                                                        
------------------------------------------------------------------------
                                                                        
(2) Alkalinity (mg/l)                                                   
TOC (mg/l).............................     0-< 60   60-< 120  8.....................................         50         40         30
------------------------------------------------------------------------

2.3  Microbial Benchmarking/Profiling

    A microbial benchmark to provide a methodology and process by 
which a PWS and the State, working together, assure that there will 
be no significant reduction in microbial protection as the result of 
modifying disinfection practices in order to meet MCLs for TTHM and 
HAA5 should be established as follows:
    A. Applicability. The following PWSs to which the IESWTR applies 
must prepare a disinfection profile:
    (1) PWSs with measured TTHM levels of at least 80% of the MCL 
(0.064 mg/l) as an annual average for the most recent 12 month 
compliance period for which compliance data are available prior to 
November 1998 (or some other period designated by the State),
    (2) PWSs with measured HAA5 levels of at least 80% of the MCL 
(0.048 mg/l) as an annual average for the most recent 12 month 
period for which data are available (or some other period designated 
by the State)--In connection with HAA5 monitoring, the following 
provisions apply:
    (a) PWSs that have collected HAA5 data under the Information 
Collection Rule must use those data to determine the HAA5 level, 
unless the State determines that there is a more representative 
annual data set.
    (b) For those PWSs that do not have four quarters of HAA5 data 
90 days following the IESWTR promulgation date, HAA5 monitoring must 
be conducted for four quarters.
    B. Disinfection profile. A disinfection profile consists of a 
compilation of daily Giardia lamblia log inactivations (or virus 
inactivations under conditions to be specified), computed over the 
period of a year, based on daily measurements of operational data 
(disinfectant residual concentration(s), contact time(s), 
temperature(s), and where necessary, pH(s)). The PWS will then 
determine the lowest average month (critical period) for each 12 
month period and average critical periods to create a ``benchmark'' 
reflecting the lower bound of a PWS's current disinfection practice. 
Those PWSs that have all necessary data to determine profiles, using 
operational data collected prior to promulgation of the IESWTR, may 
use up to three years of operational data in developing those 
profiles. Those PWSs that do not have three years of operational 
data to develop profiles must conduct the necessary monitoring to 
develop the profile for one year beginning no later than 15 months 
after promulgation, and use up to two years of existing operational 
data to develop profiles.
    C. State review. The State will review disinfection profiles as 
part of its sanitary survey. Those PWSs required to develop a 
disinfection profile that subsequently decide to make a significant 
change in disinfection practice (i.e., move point of disinfection, 
change the type of disinfectant, change the disinfection process, or 
any other change designated as significant by the State) must 
consult with the State prior to implementing such a change. 
Supporting materials for such consultation must include a 
description of the proposed change, the disinfection profile, and an 
analysis of how the proposed change will affect the current 
disinfection.
    D. Guidance. EPA, in consultation with interested stakeholders, 
will develop detailed guidance for States and PWSs on how to develop 
and evaluate disinfection profiles, identify and evaluate 
significant changes in disinfection practices, and guidance on 
moving the point of disinfection from prior to the point of 
coagulant addition to after the point of coagulant addition.

2.4  Disinfection Credit

    Consistent with the existing provisions of the 1989 Surface 
Water Treatment Rule, credit for compliance with applicable 
disinfection requirements should continue to be allowed for 
disinfection applied at any point prior to the first customer.
    EPA will develop guidance on the use and costs of oxidants that 
control water quality problems (e.g., zebra mussels, Asiatic clams, 
iron, manganese, algae) and whose use will reduce or eliminate the 
formation of DBPs of public health concern.

2.5  Turbidity

    Turbidity Performance Requirements. For all surface water 
systems that use conventional treatment or direct filtration, serve 
more than 10,000 people, and are required to filter: (a) the 
turbidity level of a system's combined filtered water at each plant 
must be less than or equal to 0.3 NTU in at least 95 percent of the 
measurements taken each month and, (b) the turbidity level of a 
system's combined filtered water at each plant must at no time 
exceed 1 NTU. For both the maximum and the 95th percentile 
requirements. compliance shall be determined based on measurements 
of the combined filter effluent at four-hour intervals.
    Individual Filter Requirements. All surface water systems that 
use rapid granular filtration, serve more than 10,000 people, and 
are required to filter shall conduct continuous monitoring of 
turbidity for each individual filter and shall provide an exceptions 
report to the State on a monthly basis. Exceptions reporting shall 
include the following: (1) any individual filter with a turbidity 
level greater than 1.0 NTU based on 2 consecutive measurements 
fifteen minutes apart; and (2) any individual filter with a 
turbidity level greater than 0.5 NTU at the end of the first 4 hours 
of filter operation based on 2 consecutive measurements fifteen 
minutes apart. A filter profile will be produced if no obvious 
reason for the abnormal filter performance can be identified.
    If an individual filter has turbidity levels greater than 1.0 
NTU based on 2 consecutive measurements fifteen minutes apart at any 
time in each of 3 consecutive months, the system shall conduct a 
self-assessment of the filter utilizing as guidance relevant 
portions of guidance issued by the Environmental Protection Agency 
for Comprehensive Performance Evaluation (CPE). If an individual 
filter has turbidity levels greater than 2.0 NTU based on 2 
consecutive measurements fifteen minutes apart at any time in each 
of two consecutive months, the system will arrange for the conduct 
of a CPE by the State or a third party approved by the State.
    State Authority. States must have rules or other authority to 
require systems to conduct a Composite Correction Program (CCP) and 
to assure that systems implement any follow-up recommendations that 
result as part of the CCP.

2.6  Cryptosporidium MCLG

    EPA should establish an MCLG to protect public health. The 
Agency should describe existing and ongoing research and areas of 
scientific uncertainty on the question of which species of 
Cryptosporidium represents a concern for public health (e.g. parvum, 
muris, serpententious) and request further comment on whether to 
establish an MCLG on the genus or species level.
    In the event the Agency establishes an MCLG on the genus level, 
EPA should make clear that the objective of this MCLG is to protect 
public health and explain the nature of scientific uncertainty on 
the issue of

[[Page 59557]]

taxonomy and cross reactivity between strains. The Agency should 
indicate that the scope of MCLG may change as scientific data on 
specific strains of particular concern to human health become 
available.

2.7  Removal of Cryptosporidium

    All surface water systems that serve more than l 0,000 people 
and are required to filter must achieve at least a 2 log removal of 
Cryptosporidium. Systems which use rapid granular filtration (direct 
filtration or conventional filtration treatment--as currently 
defined in the SWTR), and meet the turbidity requirements described 
in Section 2.5 are assumed to achieve at least a 2 log removal of 
Cryptosporidium. Systems which use slow sand filtration and 
diatomaceous earth filtration and meet existing turbidity 
performance requirements (less than 1 NTU for the 95th percentile or 
alternative criteria as approved by the State) are assumed to 
achieve at least a 2 log removal of Cryptosporidium.
    Systems may demonstrate that they achieve higher levels of 
physical removal.

2.8  Multiple Barrier Concept

    EPA should issue a risk-based proposal of the Final Enhanced 
Surface Water Treatment Rule for Cryptosporidium embodying the 
multiple barrier approach (e.g. source water protection, physical 
removal, inactivation, etc.), including, where risks suggest 
appropriate, inactivation requirements. In establishing the Final 
Enhanced Surface Water Treatment Rule, the following issues will be 
evaluated:
     Data and research needs and limitations (e.g. 
occurrence, treatment, viability, active disease surveillance, 
etc.);
     Technology and methods capabilities and limitations;
     Removal and inactivation effectiveness;
     Risk tradeoffs including risks of significant shifts in 
disinfection practices;
     Cost considerations consistent with the SDWA;
     Reliability and redundancy of systems;
     Consistency with the requirements of the Act.

2.9  Sanitary Surveys

    Sanitary surveys operate as an important preventive tool to 
identify water system deficiencies that could pose a risk to public 
health. EPA and ASDWA have issued a joint guidance dated 12/21/95 on 
the key components of an effective sanitary survey. The following 
provisions concerning sanitary surveys should be included.

I. Definition

    (A) A sanitary survey is an onsite review of the water source 
(identifying sources of contamination using results of source water 
assessments where available), facilities, equipment, operation, 
maintenance, and monitoring compliance of a public water system to 
evaluate the adequacy of the system, its sources and operations and 
the distribution of safe drinking water.
    (B) Components of a sanitary survey may be completed as part of 
a staged or phased state review process within the established 
frequency interval set forth below.
    (C) A sanitary survey must address each of the eight elements 
outlined in the December 1995 EPA/STATE Guidance on Sanitary 
Surveys.

II. Frequency

    (A) Conduct sanitary surveys for all surface water systems 
(including groundwater under the influence) no less frequently than 
every three years for community systems except as provided below and 
no less frequently than every five years for noncommunity systems.

--May ``grandfather''sanitary surveys conducted after December 1995, if 
they address the eight sanitary survey components outlined above.

    (B) For community systems determined by the State to have 
outstanding performance based on prior sanitary surveys, successive 
sanitary surveys may be conducted no less than every five years.

III. Follow Up

    (A) Systems must respond to deficiencies outlined in a sanitary 
survey report within at least 45 days, indicating how and on what 
schedule the system will address significant deficiencies noted in 
the survey.
    (B) States must have the appropriate rules or other authority to 
assure that facilities take the steps necessary to address 
significant deficiencies identified in the survey report that are 
within the control of the PWS and its governing body.

    Agreed to by:

----------------------------------------------------------------------
Name, Organization

----------------------------------------------------------------------
Date

Signed By:

Peter L. Cook, National Association of Water Companies
Michael A. Dimitriou, International Ozone Association
Cynthia C. Dougherty, US Environmental Protection Agency
Mary J.R. Gilchrist, American Public Health Association
Jeffrey K. Griffiths, National Association of People with AIDS
Barker Hamill, Association of State Drinking Water Administrators
Robert H. Harris, Environmental Defense Fund
Edward G. Means III, American Water Works Association
Rosemary Menard, Large Unfiltered Systems
Erik D. Olson, Natural Resources Defense Council
Brian L. Ramaley, Association of Metropolitan Water Agencies
Charles R. Reading Jr., Water and Wastewater Equipment Manufacturers 
Association
Suzanne Rude, National Association of Regulatory Utility 
Commissioners
Ralph Runge, Chlorine Chemistry Council
Coretta Simmons, National Association of State Utility Consumer 
Advocates
Bruce Tobey, National League of Cities
Chris J. Wiant, National Association of City and County Health 
Officials; National Environmental Health Association

[FR Doc. 97-28747 Filed 10-31-97; 8:45 am]
BILLING CODE 6560-50-P