EPA-815-Z-97-002
Monday
November 3, 1997
Part II
Environmental
Protection Agency
40 CFR Parts 141 and 142
National Primary Drinking Water
Regulations: Disinfectants and
Disinfection Byproducts; Notice of Data
Availability; Proposed Rule
59387
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59388 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
ENVIRONMENTAL PROTECTION
AGENCY
40 CFR Parts 141 and 142
[WH-FRL-5915-3]
National Primary Drinking Water
Regulations: Disinfectants and
Disinfection Byproducts Notice of Data
Availability
AGENCY: U.S. Environmental Protection
Agency (USEPA).
ACTION: Notice of data availability.
SUMMARY: In 1994 USEPA proposed a
Stage 1 Disinfectants/Disinfection
Byproducts Rule (DBPR) to reduce the
level of exposure from disinfectants and
disinfection byproducts (DBFs) in
drinking water (USEPA, 1994b). 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-
Disinfection/Disinfectants 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.
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 Stage 1 DBPR would apply to
community water systems and
nontransient noncommunity water
systems that treat their water with a
chemical disinfectant for either primary
or residual treatment. In addition,
certain requirements for chlorine
dioxide would apply to transient
noncommunity water systems because
of the short-term health effects from
high levels of chlorine dioxide.
Key issues related to the Stage 1 DBPR
that are addressed in this Notice include
the establishment of Maximum
Contaminant Levels for total
trihalomethanes, five haloacetic acids,
bromate and chlorite; requirements for
enhanced coagulation and enhanced
softening; disinfection credit; health
effects information; and analytical
methods.
Today's Federal Register also
contains a related Notice of Data
Availability for the Interim Enhanced
Surface Water Treatment Rule
(IESWTR). USEPA proposed this rule at
the same time as the Stage 1 DBPR and
plans to promulgate it along with the
Stage 1 DBPR 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
DBP 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 ow-
docket@epamail.epa.gov.
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 Thomas
Grubbs or William Hamele, Office of
Ground Water and Drinking Water (MC
4607), U.S. Environmental Protection
Agency, 401 M Street SW, Washington
DC 20460; telephone (202) 260-7270
(Grubbs) or (202) 260-2584 (Hamele).
Regional Contacts
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
Stage 1 DBPR are public water systems
that add a disinfectant or oxidant.
Regulated categories and entities
include:
Category
Public Water Sys-
tem.
State Govern-
ments.
Examples of regulated
entities
Community water sys-
tems that add disinfect-
ant or oxidant.
State government offices
that regulate drinking
water.
This table is not intended to be
exhaustive, but rather provides a guide
for readers regarding entities likely to be
regulated by the Stage 1 DBPR. This
table lists the types of entities that EPA
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 in § 141.130 of
the proposed rule published on July 29,
1994 at 59 FR 38668 (USEPA, 1994b). If
you have questions regarding the
applicability of this action 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
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Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
59389
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 tiiis 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. 401M. 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.
Abbreviations Used in This Notice
AOC: Assimilable organic carbon
ASDWA: Association of State Drinking
Water Administrators
AWWA: American Water Works
Association
AWWARF: AWWA Research
Foundation
AWWSCo: American Water Works
Service Company
BAG: Biologically active carbon
BAF: Biologically active filtration
BAT: Best Available Technology
BCAA: Bromochloroacetic acid
BDOC: Biodegradable organic carbon
CT: Contact time
CWS: Community Water System
DBF: Disinfection byproducts
D/DBP: Disinfectants and disinfection
byproducts
DBPRAM: DBP Regulatory Analysis
Model
DOC: Dissolved Organic Carbon
EPA: United States Environmental
Protection Agency
ESWTR: Enhanced Surface Water
Treatment Rule
FACA: Federal Advisory Committee Act
FY: Fiscal year
GAC: Granular Activated Carbon
GWDR: Ground Water Disinfection Rule
HAAS: Haloacetic acids (five)
1C: Ion chromotography
ICR: Information Collection Rule
ILSI: International Life Sciences
Institute
IOC: Inorganic chemical
LOAEL: Lowest observed adverse effect
level
MCL: Maximum Contaminant Level
(expressed as mg/1,1,000 micrograms
(|ig)=l milligram (mg))
MCLG: Maximum Contaminant Level
Goal
M-DBP: Microbial and Disinfectants/
Disinfection Byproducts
MDL: Method Detection Limit
mg/dl: Milligrams per deciliter
mg/L: Milligrams per liter
MGD: Million Gallons per Day
MRDL: Maximum Residual Disinfectant
Level (as mg/1)
MRDLG: Maximum Residual
Disinfectant Level Goal
MWDSC: Metropolitan Water District of
Southern California
NCI: National Cancer Institute
NIPDWR: National Interim Primary
Drinking Water Regulation
NOAEL: No observed adverse effect
level
NOM: Natural Organic Matter
NPDWR: National Primary Drinking
Water Regulation
NTNCWS: Nontransient noncommunity
water system
O&M: Operations and maintenance
PE: Performance evaluation
POOR: Point of Diminishing Returns
POE: Point-of-Entry Technologies
POU: Point-of-Use Technologies
ppb: Parts per billion
PQL: Practical Quantitation Level
PWS: Public Water System
RIA: Regulatory Impact Analysis
RMCL: Recommended Maximum
Contaminant Level
SAB: Science Advisory board
SDWA: Safe Drinking Water Act, or the
"Act," as amended in 1986
SUVA: Specific ultraviolet absorbance
at 254 nm
SWTR: Surface Water Treatment Rule
TOC: Total organic carbon
TTHM: Total trihalomethanes
TWG: Technical Working Group
UNC: University of North Carolina
VOC: Volatile Synthetic Organic
Chemical
WIDE: Water Industry Data Base
WITAF: Water Industry Technical
Action Fund
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 apd 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 DBP Proposal
1. MCLGs/MCLs/MRDLGs/MRDLs
2. Best available technologies
3. Treatment technique
4. Preoxidation (predisinfection) credit
5. Analytical methods
6. New information
II. Health Effects
A. Cancer Epidemiology Studies
1. Expert panels recommendations on
cancer epidemiology
2. Implementation of expert panel
recommendations
a. Improve exposure assessments/
geographic identification studies/classes
of DBFs other than THMs
b. Meta-analysis of existing cancer
epidemiology data
B. Reproductive and Developmental
Epidemiology Studies
1. Improving exposure assessments
2. New studies since proposal
C. Significant New Toxicological
Information for Stage 1 Disinfectants and
Disinfection Byproducts
1. Chlorite
2. Chlorine dioxide
3. Trihalomethanes
4. Haloacetic acids
5. Chloral hydrate
6. Bromate
D. Summary of Key Observations
E. Request for Public Comments
HI. Enhanced Coagulation and Enhanced
Softening
A. 1994 Enhanced Coagulation and
Enhanced Softening Proposal
B. New Information on Enhanced
Coagulation and Softening Since 1994
Proposal
1. New Data on enhanced coagulation
a. UNC Enhanced Coagulation Study
b. Metropolitan Water District of Southern
California WDSC/ColoradoUniversity
Enhanced Coagulation Study
c. Malcolm Pirnie, Inc./Colorado
University data collection and analysis
d. Evaluation of current (baseline) TOC
removals at full scale
e. Evaluation of "optimized" TOC removal
f. "Case-by-case" data analyses
2. New data on enhanced softening
a. AWWARF Studies—data on TOC
removal
b. Shorney and Coworkers—data on the
use of SUVA
c. Malcolm Pirnie, Inc. modeling
d. ICR mail survey
C. Summary of Key Enhanced Coagulation
and Enhanced Softening Observations
D. Request for Public Comment on
Enhanced Coagulation and Enhanced
Softening Issues
IV. Predisinfection Credit
A. 1994 Proposal
B. New Information Since 1994 Proposal
1. ICR mail survey—predisinfection
practices
2. Summers et al.—Impact of chlorination
point on DBP production
C. Summary of Key Observations
D. Request for Public Comments
V. Analytical Methods
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A. Chlorine Dioxide
B. Haloacetic Acids
C. Total Trihalomethanes (TTHMs)
D. Bromate
E. Chlorite
F. Total Organic Carbon (TOC)
G. Specific Ultraviolet Absorbance (SUVA)
H. Summary of Key Observations
I. Request for Public Comments
VI. MCLs for TTHMs, HAAs, Chlorite, and
Bromate
A. 1994 Proposal
B. New Information Since 1994 Proposal
1. TTHM and HAAS MCLs
2. Bromate
3. Chlorite
VH. Regulatory Compliance Schedule and
Other Compliance-related Issues
A. Regulatory Compliance Schedule
B. Compliance violations and State
primacy obligations
C. Compliance with current regulations
VIII. Economic Analysis of the M-DBP
Advisory Committee Recommendations
A. Plant-level DBF Treatment Effectiveness
and Cost
B. Decision Tree Analysis—Compliance
Forecasts
C. National Cost Estimates
1. System level costs
2. Household costs
3. Monitoring and State implementation
costs
D. DBF Exposure Estimates
E. National Benefits Analysis
F. Cost-Effectiveness
G. Summary of Key Observations
H. Request for Public Comments
IX. National Technology Transfer and
Advancement Act
X. References
I. Introduction and Background
A. Existing Regulations
1. Surface Water Treatment Rule
Under the Surface Water Treatment
Rule (SWTR)(USEPA, 1989a), 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 CTTHMs) of 0.10 mg/1
as an annual average in November 1979
(USEPA, 1979). 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 (USEPA,
1989b) was revised in June 1989, and
became effective on December 31, 1990.
The rule, which applies to all public
water systems, 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-positives;
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
(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 DBFs. 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 DBFs
concluded that additional information
was needed to assess the potential
health problem created by the presence
of DBFs 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, an independent panel
established by Congress, cited drinking
water contamination as one of the
highest ranking environmental risks.
The Science Advisory board reported
that microbiological contaminants (e.g.
bacteria, protozoa, viruses) are likely the
greatest remaining health risk
management challenge for drinking
water suppliers. The control of
microbiological contaminants is further
complicated because commonly-used
disinfection processes themselves may
pose health risks. Conventional
practices require the addition of
disinfectant chemicals to the water that,
while effective in controlling many
harmful microorganisms, combine with
organic matter in the water and form
compounds known as disinfection
byproducts (DBFs). One of the most
complex questions facing water supply
professionals is how to minimize the
risks from these DBFs and still control
microbial contaminants.
Chemical disinfectants (e.g., chlorine,
chloramines, chlorine dioxide) are
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59391
added to drinking water to provide
continuous disinfection throughout the
distribution system. There is generally
Hide health concern over exposure to
the levels of the disinfectant residuals
commonly found in finished drinking
water. A number of organic DBFs,
including some trihalomethanes
(chloroform, bromoform, and
bromodichloromethane) and some
haloacetic acids (e.g., dichloroacetic
acid) cause cancer in laboratory
animals. Other DBFs cause reproductive
or developmental effects in laboratory
animals (e.g., chlorite). Bromate, a
byproduct of ozonation, causes cancer
In laboratory animals.
Several epidemiology studies have
evaluated the association of chlorination
and chloramination with several
adverse outcomes including cancer,
cardiovascular disease, and adverse
reproductive outcomes. Several studies
have reported small increases in
bladder, colon, and rectal cancers. In
some cases, these effects appeared to be
associated with the duration of exposure
and volume of water consumed. Data on
DBFs and cardiovascular disease are
Inconclusive, Animal studies in the mid
1980's indicated a potential increase in
the serum Hpid levels in animals
exposed to chlorinated water. However,
In a cross-sectional epidemiology study
In humans, comparing chlorinated and
unchlorinated water supplies with
varying water hardness, no adverse
effects on serum llpid levels were
found. Recent epidemiology studies
have reported increased incidence of
decreased birth weight, premature
births, intrauterine growth retardation,
and neural tube defects with chlorinated
water. As with the other reported
adverse outcomes from the
epidemiology studies, there is
considerable debate in the scientific
community on the significance of these
findings (USEPA. 1994a). A discussion
of new health effects information that
has become available since the 1994
proposal appears in Section VI of this
Notice.
In order to accurately assess risk from
DBFs, It Is important to have
information on human exposure to
DBFs, Information on the toxicity of the
DBFs and an understanding of the mode
of action of toxicity. The preamble to
the 1994 proposed DBF rule presented
information on the occurrence and
exposure to the Stage 1 DBFs. The
information presented in that preamble
was summarized from the document
"Occurrence Assessment for
Disinfectants and Disinfection By-
products (Phase 6a) in Drinking Water"
(USEPA, 1992a) and from information
presented as a part of the 1992 and 1993
Regulatory Negotiation process that led
to the 1994 Stage 1 DBF proposal (see
section D below). Since the proposal,
USEPA has updated the document cited
above with new occurrence and
exposure information. Copies of the
revised document, entitled "Occurrence
Assessment for Disinfectants and
Disinfection Byproducts in Public
Drinking Water Supplies" (USEPA,
1997a) can be obtained from the Docket
for this Notice. The Information
Collection Rule (ICR) (USEPA, 1996b)
will supply additional information on
the occurrence of DBFs for the Stage 2
DBF rule; however, this ICR information
will not be available in time for the
Stage 1 DBF rule.
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
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
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)(Q).
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
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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)(l)(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 dirough 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
DBF risk on a plant-specific basis were
unavailable. Nevertheless, the
Committee agreed that USEPA propose
a Disinfectant/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 DBFs
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 DBFs and that
these chemicals do not pose an
unacceptable risk at these limits.
Following months of intensive
discussions and technical analysis, die
Committee recommended die
development of three sets of rules: a
two-staged Disinfectants/Disinfection
Byproduct Rule (proposal: 59 FR 38668,
July 29, 1994), an "interim" ESWTR
(proposal: 59 FR 38832, July 29, 1994),
and an Information Collection rule
(proposal: 59 FR 6332, February 10,
1994). 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
DBFs. 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 die protozoan,
Cryptosporidium. The Committee also
agreed that the schedules for IESWTR
and LTESWTR should be "linked" to
the schedule for the Stage 1 DBF 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 mediods needed to be
developed in order to better understand
die risk-risk tradeoff, and how to
accomplish an overall reduction in risk.
Finally the Negotiating Committee
agreed diat to develop a reasonable set
of rules and to understand more fully
the limitations of die current SWTR,
additional field data were critical. Thus,
a key component of die regulation
negotiation agreement was the
promulgation of die 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 die data
collection effort. Under die ICR, these
PWSs monitor their source water for
bacteria, viruses, and protozoa (surface
water sources only); water quality
factors affecting DBF formation; and
DBFs within the treatment plant and in
the distribution system. In addition,
PWSs must provide operating data and
a description of dieir treatment plan
design. Finally, a subset of PWSs
perform treatment studies, using eidier
granular activated carbon or membrane
processes, to evaluate DBF precursor
removal. Monitoring for treatment study
applicability began in September 1996.
The remaining occurrence monitoring
began in July 1997.
The initial intent of die ICR was to
collect monitoring data and other
information for use in developing die
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 die ICR data, die
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 widi stakeholders in analyzing
and using die comprehensive ICR data
and research for developing subsequent
revisions to die SWTR and die Stage 2
DBF Rule.
F. Formation of 1997Federal Advisory
Committee
In May 1996, the Agency initiated a
series of public informational meetings
to exchange information on issues
related to microbial and disinfectants/
disinfection byproducts regulations. To
help meet die deadlines for the IESWTR
and Stage 1 DBPR established by
Congress in die 1996 SDWA
Amendments and to maximize
stakeholder participation, die Agency
established the Microbial and
Disinfectants/Disinfection Byproducts
(M-DBP) Advisory Committee under die
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 tiiis 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 dirough July 1997, to discuss
issues related to the IESWTR and Stage
1 DBPR. Technical support for diese
discussions was provided by a
Technical Work Group (TWG)
established by die Committee at its first
meeting in March 1997. The
Committee's activities resulted in die
collection, development, evaluation,
and presentation of substantial new data
and information related to key elements
of bodi proposed rules. The Committee
reached agreement on the following
major issues discussed in this Notice
and the Notice for die IESWTR
published elsewhere in today's Federal
Register: (1) MCLs forTTHMs, HAAS
and bromate; (2) requirements for
enhanced coagulation and enhanced
softening (as part of DBF control); (3)
microbial benchmarking/profiling to
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59393
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 HAAS; (4)
disinfection credit; (5) turbidity; (6)
Cryptospoddium MCLG; (7) removal of
Ciyptosporidium; (8) role of
Ciyptosporidium 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 1994 DBF Proposal
The proposed Disinfectants and
Disinfection Byproducts Stage I Rule
(DBPQ addressed a number of complex
and Interrelated drinking water issues.
The proposal attempted to balance the
control of health risks from compounds
formed during drinking water
disinfection against the risks from
microbial organisms (such as Glardia
lamblla, Ciyptosporidium, bacteria, and
viruses) to be controlled by the IESWTR.
The proposed Stage 1 DBP rule
applied to all community water systems
(CWSs) and nontransient
noncommunlty water systems
(NTNCWSs) that treat their water with
a chemical disinfectant for either
primary or residual treatment. In
addition, certain requirements for
chlorine dioxide would apply to
transient noncommunity water systems
because of the short-term health effects
from high levels of chlorine dioxide.
Following is a summary of key
components of die 1994 Stage 1 DBPR
proposal.
1. MCLGs/MCLs/MRDLGs/MRDLs
EPA proposed MCLGs of zero for
chloroform, bromodichloromethane,
bromoform, bromate, and dichloroacetic
acid and MCLGs of 0.06 mg/L for
dibromochloromediane, 0.3 mg/L for
trichloroacetic acid, 0.04 mg/L for
chloral hydrate, and 0.08 mg/L for
chlorite. In addition, EPA proposed to
lower the MCL for TTHMs from 0.10 to
0.080 mg/L and added an MCL for five
haloacetlc acids (i.e., the sum of the
concentrations of mono-, di-, and
trichloroacetic acids and mono-and
dibromoacetic acids) of 0.060 mg/L.
EPA also, for the first time, proposed
MCLs for two inorganic DBFs: 0.010 mg/
L for bromate and 1.0 mg/L for chlorite.
In addition to proposing MCLGs and
MCLs for several DBFs, EPA proposed
maximum residual disinfectant level
goals (MRDLGs) of 4 mg/L for chlorine
and chloramines and 0.3 mg/L for
chlorine dioxide. The Agency also
proposed maximum residual
disinfectant levels (MRDLs) for chlorine
and chloramines of 4.0 mg/L, and 0.8
mg/L for chlorine dioxide. MRDLs
protect public health by setting limits
on the level of residual disinfectants in
the distribution system. MRDLs are
similar in concept to MCLs—MCLs set
limits on contaminants and MRDLs set
limits on residual disinfectants in the
distribution system. MRDLs, like MCLs,
are enforceable, while MRDLGs, like
MCLGs, are not enforceable.
2. Best Available Technologies
EPA identified the best available
(BAT) technology for achieving
compliance with the MCLs for both
TTHMs and HAAS as enhanced
coagulation or treatment with granular
activated carbon with a ten minute
empty bed contact time and 180 day
reactivation frequency (GAG 10), with
chlorine as the primary and residual
disinfectant. The BAT for achieving
compliance with the MCL for bromate
was control of ozone treatment process
to reduce formation of bromate. The
BAT for achieving compliance with the
chlorite MCL was control of precursor
removal treatment processes to reduce
disinfectant demand, and control of
chlorine dioxide treatment processes to
reduce disinfectant levels. EPA
identified BAT for achieving
compliance with the MRDL for chlorine,
chloramine, and chlorine dioxide as
control of precursor removal treatment
processes to reduce disinfectant
demand, and control of disinfection
treatment processes to reduce
disinfectant levels.
3. Treatment Technique
EPA proposed a treatment technique
that would require surface water
systems and groundwater systems under
the direct influence of surface water that
use conventional treatment or
precipitative softening to remove DBP
precursors by enhanced coagulation or
enhanced softening. A system would
have been required to remove a certain
percentage of TOC (based on raw water
quality) prior to the point of continuous
disinfection. EPA also proposed a
procedure to be used by a PWS not able
to meet the percent reduction, to allow
them to comply with an alternative
minimum TOC removal level.
Compliance for systems required to
operate with enhanced coagulation or
enhanced softening was based on a
running annual average, computed
quarterly, of normalized monthly TOC
percent reductions. A complete
discussion of the proposed requirements
is in Section III.A.
4. Preoxidation (Predisinfection) Credit
The proposed rule did not allow
PWSs required to use enhanced
coagulation or enhanced softening to
take credit for compliance with
disinfection requirements in die SWTR/
IESWTR prior to removing required
levels of precursors unless they met
specified criteria. These criteria are
explained in Section IV.A.
5. Analytical Methods
EPA proposed nine analytical
methods (some of which can be used for
multiple analytes) to ensure compliance
with proposed MRDLs for chlorine,
chloramines, and chlorine dioxide. The
three disinfectant residuals were
measured and reported as: chlorine as
free chlorine (four methods) or total
chlorine (five methods); chloramines as
combined chlorine (three methods) or
total chlorine (five methods); and
chlorine dioxide as chlorine dioxide (3
methods). EPA proposed methods for
die analysis of two classes of organic
DBFs: TTHMs (three mediods) and
HAAS (2 methods). In addition, EPA
proposed one method for measuring
both inorganic DBFs (chlorite and
bromate) and two methods for total
organic carbon (TOC).
6. New Information
Since July, 1994, new information has
become available in several key areas
related to issues put forth in the DBP
Stage 1 proposal. The key issues where
new information has become available
since die proposal include the
following: (1) MCLs; (2) Enhanced
Coagulation and Enhanced Softening;
(3) Predisinfection Credit; (4) Health
Effects Information; (5) Analytical
Methods; and (6) the Regulatory Impact
Analysis (DBP and TOC occurrence,
compliance decision tree). This
information and its implications are
discussed in more detail below.
II. Health Effects
The preamble to the 1994 proposed
rule provided a summary of the health
criteria documents for bromate;
chloramines; haloacetic acids and
chloral hydrate; chlorine; chlorine
dioxide, chlorite, and chlorate; and
trihalomethanes. The information
presented in the proposal was used to
establish MCLGs and MRDLGs for the
disinfectants and DBFs listed above.
Since the 1994 proposal, several
epidemiology and toxicology studies
have been completed. The study results
need to be considered for the final Stage
1 DBPR. The following section briefly
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discusses the new epidemiological and
laboratory toxicology studies. In
addition, USEPA has developed
summaries of this new information and
included these documents in the Docket
for this action as "Summaries of New
Health Effects Data" (USEPA, 1997b).
A. Cancer Epidemiology Studies
The preamble to the proposed rule
discussed several cancer epidemiology
studies that had been conducted over
the past 20 years on chlorinated
drinking water (see USEPA, 1994b). At
the time of the proposed rule, there was
disagreement among the members of the
Negotiating Committee on the
conclusions to be drawn from the cancer
epidemiology studies. Some members of
the Committee felt that the cancer
epidemiology data, taken in conjunction
with the results from toxicological
studies, provide an ample and sufficient
weight of evidence to conclude that
exposure to DBFs in drinking water
could result in an increased cancer risk
at levels encountered in some public
water supplies. Other members of the
Committee concluded that the degree of
resolution in cancer epidemiology
studies on the consumption of
chlorinated drinking water to date was
insufficient to provide definitive
information for the regulation. USEPA,
therefore, agreed to pursue additional
research to reduce the uncertainties
associated with these epidemiology data
and to better characterize and project
the potential human cancer risks
associated with the consumption of
chlorinated drinking water. To
implement this commitment, USEPA
sponsored two expert panel reviews on
the state of cancer epidemiology. Each
of these panels recommended short and
long-term research for improving the
assessment of risks using cancer
epidemiology.
1. Expert Panels Recommendations on
Cancer Epidemiology
USEPA conducted an expert panel
workshop in July 1994 on the scientific
considerations for conducting cancer
epidemiologic studies for DBFs (USEPA,
1994a). The expert panel presented the
following conclusions.
(Although ecological and analytic
epidemiologic studies have reported
associations between chlorinated water and
cancer at various sites, many of the studies
have methodologic problems or systematic
biases that limit the interpretation of results.
Moreover, the studies vary according to the
amount of information available on exposure
to chlorinated water or DBFs. The panel
agrees that existing epidemiologic data are
insufficient to conclude that the reported
associations are causal or provide an accurate
estimate of the magnitude of risk.
This cancer workshop panel also
provided several recommendations for
conducting additional research. These
included: (1) improving exposure
assessments; (2) conducting a reanalysis
of previously conducted interview-
based case control studies using
improved exposure estimates and
analytical methods to determine the
validity of these risks and to address
confounding factors and bias not
adequately excluded in previous reports
such as the meta-analysis completed by
Morris, et al. (1992) discussed in the
1994 proposed rule (USEPA, 1994b,
page 38689); (3) conducting feasibility
studies to identify geographic locations
with adequate exposure data and
appropriate cohorts for study (including
the possibility of using existing cohorts
that are being studied for other potential
exposures); and (4) consideration of
several possible designs for full scale
studies (i.e., cohort, case-control, and
case-control nested within a cohort).
In October 1995, the International Life
Sciences Institute (ILSI) sponsored a
workshop on "Disinfection by-products
in Drinking Water: Critical Issues in
Health Effects Research" (ILSI, 1995).
One of the panels at the workshop
provided a brief summary of the
findings from cancer epidemiology
studies and made recommendations for
further research in this area. The panel
concluded that the epidemiological
studies of bladder and colorectal cancer
have generally shown an increased risk
associated with the consumption of
chlorinated surface water, although a
causal association has not been
conclusively established. The panel
made several recommendations for
future research including the need to
conduct hypothesis driven cancer
epidemiological studies to examine the
risk of classes of DBFs other than THMs
and to support these studies with
improved exposure assessments.
2. Implementation of Expert Panel
Recommendations
a. Improve Exposure Assessments/
Geographic Identification Studies/
Classes of DBFs Other Than THMs.
USEPA, in conjunction with other
parties, has begun research to provide
the tools needed to improve exposure
assessments for epidemiology studies.
USEPA is supporting studies in
Colorado, North Carolina, and New
Jersey that will provide improved tools
for conducting exposure assessments for
epidemiology studies. While the results
from these studies will not be available
for the final Stage 1 DBF rule, they will
be very useful in designing future
epidemiology studies.
In addition to USEPA's research, the
Microbial/DBP Research Council (M/
DBF Council) is funding a study on
"Identification of Geographic Areas for
Possible Epidemiological Studies" and
is evaluating several proposals for a
project on "Development of Methods for
Predicting THM and HAA
Concentrations in Exposure Assessment
Studies." The M/DBP Council was
formed as a joint USEPA and American
Water Works Association Research
Foundation (AWWARF) project to
identify and fund critical research. This
research, in conjunction with the
USEPA research discussed above, will
improve the understanding of risks
associated with the consumption of
chlorinated surface water. However, as
with USEPA's work, this research will
not be completed in time to impact the
Stage 1 DBPR.
b. Meta-analysis of Existing Cancer
Epidemiology Data. The 1994 proposal
includes results of a meta-analysis that
pooled the relative risks from 10 cancer
epidemiology studies in which there
was a presumed exposure to chlorinated
water and its byproducts (Morris et al.,
1992). This meta-analysis estimated that
approximately 10,000 cancer cases each
year could be attributed to the
consumption of chlorinated drinking
water and its byproducts. As discussed
in the preamble to the proposed rule,
this study generated considerable debate
among the members of the Negotiation
Committee. An evaluation of the Morris
et al. meta-analysis has been recently
completed for USEPA. USEPA is
currently evaluating this report and will
provide an opportunity to comment on
EPA's assessment and implications for
the regulatory provisions for the final
Stage 1 DBPR.
In addition to the meta-analysis,
USEPA has summarized several new
cancer epidemiology studies and
included them as part of the
"Summaries of New Health Effects
Data" (USEPA, 1997b) that is included
in the Docket for this Notice. USEPA
will be evaluating the data from the new
epidemiology studies and will provide
an opportunity to comment on the
potential implications of these new
studies for the regulatory provisions for
the final Stage 1 DBPR.
B. Reproductive and Developmental
Epidemiology Studies
The preamble to the 1994 proposal
discussed several reproductive
epidemiology studies that had been
conducted (see USEPA, 1994b, page
38690). It also included a discussion of
an USEPA and ILSI expert panel that
reviewed the published epidemiologic
and experimental data on reproductive
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59395
and developmental effects and a strategy
developed by the panel for related short-
term and long-term research (USEPA,
1993b). The panel concluded that the
currently available data on the effects of
chlodnatlon byproducts provide an
Inadequate basis for identifying DBFs as
a reproductive or developmental hazard.
Recommendations were made for
refining studies using existing data
bases, strengthening studies designed to
collect new data, improving exposure
assessments, investigating selected
health endpoints, and developing a
stronger link between animal research
and epidemiology studies.
The results from the ILSI expert
panel, and additional information
provided since the 1994 proposal, are
summarized in Reif et al. (1996). This
paper reviewed the available
epidemiological data on the reported
association between the consumption of
chlorinated drinking water and
reproductive and developmental effects.
The panel reached the following
conclusions. "The currently available
human studies on effects of chlorination
by-products provide an inadequate basis
for identifying DBFs as a reproductive
or developmental hazard. Nevertheless,
additional laboratory animal and
epidemiological research should be
conducted, employing a coordinated
muki disciplinary approach." They also
provided recommendations for short-
and longer-term research.
1. Improving Exposure Assessments
Many of the exposure assessment
projects identified above for cancer
epidemiology are also relevant to
improving exposure assessments for
evaluating reproductive and
developmental effects. As discussed in
the cancer epidemiology section, while
the results from these studies will not be
available for the final Stage 1 DBPR,
they will be very useful in designing
future reproductive epidemiology
studies.
2. New Studies Since Proposal
Since die proposal, several new
reproductive and developmental
epidemiology studies have been
published. Additionally, studies in
California and Colorado are nearing
completion, but results will not be
available for this NODA. Savitz et al.
(1995) used data from a population-
based case-control study to evaluate the
potential risk of miscarriage, preterm
delivery and low birth weight in North
Carolina based on water source, amount
of water consumed, and TTHM
concentration in water. The authors
concluded, "These data do not indicate
a strong association between chlorinated
byproducts and adverse pregnancy
outcome, but given the limited quality
of the exposure assessment and the
increased miscarriage risk in the higher
exposure group, more refined evaluation
is warranted."
Kanitz et al. (1996) conducted an
epidemiology study in Italy on the
association between somatic parameters
(e.g., birthweight, body length, cranial
circumference, and neonatal jaundice)
and drinking water disinfection with
chlorine dioxide and/or sodium
hypochlorite. The authors concluded,
"The study provides some new
information on the possible association
between some drinking water
disinfection treatments and somatic
parameters of infants at birth. Further
investigations will be needed to verify
the results of the present study by
rigorous'exposure assessments."
The 1994 proposed rule reported the
results of a New Jersey Department of
Health report on the results of a cross-
sectional study evaluating the
association between drinking water
contaminants with low birth weight and
selected birth defects (Bove et al., 1992a,
1992b). Since the proposal, an article
summarizing the cross-sectional study
has been published by Bdve et al.
(1995). The results are consistent with
those reported in the proposed Stage 1
DBPR. The authors concluded, "By
itself, this study cannot resolve whether
the drinking water contaminants caused
the adverse birth outcomes; therefore,
these findings should be followed up
utilizing available drinking water
contamination databases."
• While the new epidemiology studies
add to the database on the potential
reproductive and developmental effects
from DBFs, USEPA believes that the
results are inconclusive. A more
complete discussion of the new
reproductive and development
epidemiology studies can be found in
the "Summaries of New Health Effects
Data" (USEPA, 1997b).
C. Significant New Toxicological
Information for the Stage 1 Disinfectants
and Disinfection Byproducts
Since the proposal, new toxicological
information has become available for
several of the disinfectants and DBFs.
The information presented below is a
summary of the significant new
information for several disinfectants and
DBFs. For a more complete discussion
of the new information see the
"Summaries of New Health Effects
Data" (USEPA, 1997b) in the Docket (a
summary of the new information for
chlorine and chloramines is not
included below, but is included in the
document cited above.)
1. Chlorite
The 1994 proposal included an MCLG
of 0.08 mg/L and an MCL of 1.0 mg/L
for chlorite. In order to fill an important
data gap, the Chemical Manufacturers
Association (CMA) agreed to conduct a
two-generation reproductive effects
study of chlorite. The Negotiating
Committee agreed that if the studies
indicated that a level of 1.0 mg/L of
chlorite is safe, the MCL would remain
at 1.0 mg/L. If the studies indicate that
a level of 1.0 mg/L of chlorite is not safe
or, if such a study is not conducted, the
MCL would be re-evaluated.
After the Negotiating Committee
agreed to support a proposed MCL of 1.0
mg/L, USEPA selected developmental
neurotoxicity hazard as the critical
effect for chlorite (Mobley et al., 1990)
Based on this 1990 rat developmental
study, an MCLG of 0.08 mg/L was
derived for chlorite. USEPA believed
that the MCL of 1.0 mg/L agreed to by
the Committee was not adequate to
protect the public from the acute
developmental health effects of chlorite.
USEPA decided to propose an MCL of
1.0 mg/L to honor the agreement of the
Committee and requested comment on
several possible approaches for
promulgating the final rule.
Since the proposal, a study on the
subchronic toxicity of sodium chlorite
in rats (Harrington et al., 1995a) and a
developmental toxicity study in rabbits
(Harrington, et al., 1995b) have been
published. Both of these studies
reported no adverse toxicological
effects. Other than the two-generation
reproductive study cited above, which
USEPA recently received, relevant new
literature has not been found that would
alter the assessment for chlorite from
the 1994 proposal. USEPA is conducting
an external peer review of the CMA two-
generation reproductive study. These
peer review comments will be included
in the Docket for this NODA when they
become available. USEPA will evaluate
the data from the CMA study, including
the peer review, and will provide an
opportunity to comment on the
potential implications for the regulatory
provisions for chlorite prior to the final
Stage 1 DBF rule. The CMA study is
included in the Docket for this action
(CMA, 1997).
2. Chlorine Dioxide
The proposed Stage 1 DBPR included
a MRDLG of 0.3 mg/L and a MRDL of
0.8 mg/L for chlorine dioxide. The
proposed MRDLG for chlorine dioxide
was based on developmental
neurotoxicity as the critical effect (Orme
et al., 1985). The Negotiating Committee
agreed to the MRDL of 0.8 mg/L for
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chlorine dioxide with certain
qualifications and reservations. As cited
above, the Committee agreed that a two-
generation reproductive study on
chlorite would be completed for
consideration in the final Stage 1 DBPR.
Toxicity information on chlorite is
considered relevant for characterizing
the toxicity of chlorine dioxide. If the
chlorite study indicated no concern
from reproductive effects at 0.8 mg/L,
then the proposed MRDL for chlorine
dioxide would remain die same as
proposed. If these new data indicate
reproductive or developmental effects,
then the MRDL will need to be re-
examined comparing the tradeoffs and
regulatory impacts of a lower chlorine
dioxide MRDL and the positive aspects
of using chlorine dioxide as a
disinfectant.
Other than the two-generation
reproductive study conducted by CMA
for chlorite, there is no new literature
that would alter the assessment for
chlorine dioxide from the 1994
proposal. As stated above, USEPA
believes that the results from the
chlorite study are applicable for
addressing the toxicity data gaps for
chlorine dioxide. USEPA will evaluate
the data from the CMA study, including
the peer review, and will provide an
opportunity to comment on the
potential implications for the regulatory
provisions for chlorine dioxide prior to
the final Stage 1 DBF rule.
3. Trihalomethanes
The proposed rule includes an MCL
for total trihalomethanes (TTHM) of
0.080 mg/L. MCLGs of zero for
chloroform, bromodichloromethane
(BDCM), and bromoform were based on
sufficient evidence of carcinogenicity in
animals. The MCLG of 0.060 mg/L for
dibromochloromediane (DBCM) was
based on observed liver toxicity from a
subchronic study and possible
carcinogenicity. Since the 1994
proposal, several new studies have been
published on the metabolism for BDCM
and chloroform (Testai et al., 1995;
Gemma et al., 1996a, 1996b; Gao et al.,
1996; Nakajima et al., 1995). In addition,
several new studies were found
concerning the genotoxicity of
chloroform, BDCM, and bromoform
(Roldan-Arjona and Pueyo, 1993;
LeCurieux et al., 1995; Pegram et al.,
1997; Larson et al., 1994c; Fujie et al.,
1993; Shelby and Witt, 1995; Hayashi et
al., 1992; Sofuni et al., 1996; Matsuoka
et al., 1996; Miyagawa et al., 1995;
Banerji and Fernandes, 1996; and Potter
et al., 1996). There are considerable new
data on cytotoxicity and regenerative
cell proliferation in the liver and kidney
of rats and mice under various
conditions (Larson et al., 1993, 1994a,
1994b, 1994c, 1995a, 1995b, 1996;
Templin et al., 1996a, 1996b). Many
other studies also examined the
mechanism of chloroform
carcinogenicity, including studying the
effects on methylation and expression of
growth control genes (Fox et al., 1990,
Vorce and Goodman, 1991, Dees and
Travis, 1994, Testai et al., 1995,
Sprankle et al., 1996, Chiu et al., 1996,
Gemma etal., 1996a, 1996b). Short-term
toxicity studies (Thorton-Manning et al.,
1994; Lilly et al., 1994 and 1996) and
chronic toxicity studies which included
reproductive evaluations (Klinefelter et
al., 1995) were found for BDCM.
The new studies on THMs contribute
to the weight-of-evidence conclusions
reached in the 1994 proposal. Based on
the available new studies noted above,
die proposed MCLGs for BDCM, DBCM,
and bromoform are not anticipated to
change.
The International Life Science
Institute (ILSI) convened an expert
panel in 1996 to explore the application
of die USEPA's 1996 Proposed
Guidelines for Carcinogen Risk
Assessment (USEPA, 1996a) to the
available data on the potential
carcinogenicity of chloroform and
dichloroacetic acid (DCA); these data
include chronic bioassay data and
information on mutagenicity,
metabolism, toxicokinetics and mode of
carcinogenic action. USEPA will be
evaluating the data from the ILSI expert
panel for chloroform and will provide
an opportunity to comment on the
potential implications for the regulatory
provisions for chloroform and the
trihalomethanes prior to the final Stage
1 DBF rule.
4. Haloacetic Acids
The proposed rule included an MCL
of 0.060 mg/L for the haloacetic acids
(five HAAs-monobromoacetic acid,
dibromoacetic acid, monochloroacetic
acid, dichloroacetic acid, and
trichloroacetic acid) with an MCLG of
zero for dichloroacetic acid (DCA) based
on sufficient evidence of carcinogenicity
in animals, and a MCLG of 0.3 mg/L for
trichloroacetic acid (TCA) based on
developmental toxicity and possible
carcinogenicity.
There has been cancer research
completed for other HAAs since the
1994 proposal. The 1994 proposal did
not include an MCLG for
monochloroacetic acid (MCA) because
there were inadequate occurrence data
for MCA. Since the proposal, a few
toxicological studies on MCA have been
identified. A recent 2-year
carcinogenicity study on MCA and
trichloroacetic acid (TCA) (DeAngelo et
al., 1997) demonstrated tfiat MCA and
TCA were not carcinogenic in male rats.
This confirms the results of the NTP
(1990) cancer rodent bioassays of MCA.
There have been several recent studies
examining the mode of carcinogenic
action for both DCA and TCA (Pereira
and Phelps 1996; and Pereira 1996)
including mutagenicity studies (Austin
et al., 1996; Mackay et al., 1995; Fox et
al., 1996; Fuscoe etal., 1996; Tao et al.,
1996; and Parrish et al., 1996). As
discussed above USEPA will evaluate
the significance of the ILSI panel's
report on die risk assessment for DCA
and provide an opportunity to comment
on the potential implications for the
regulatory provisions for DCA and the
other haloacetic acids prior to die final
Stage 1 DBF rule.
Screening studies have shown the
potential of different haloacetic acids,
including DCA and brominated
haloacetic acids, to produce
reproductive and developmental effects
(Linderetal., 1997c; Hunter etal., 1996;
Richard and Hunter, 1996; Linder et al.
1994, 1995, 1997a, 1997b). At this time,
these new studies are not expected to
alter the MCLGs for DCA or TCA in the
proposed rule. USEPA continues to
believe that there are inadequate
occurrence data to establish MCLGs for
MCA, monobromoacetic acid and
dibromoacetic acid.
5. Chloral Hydrate
The proposed rule included an MCLG
of 0.04 mg/L for chloral hydrate. USEPA
did not set an MCL for chloral hydrate
because it believed the MCLs for TTHM
and HAAS, and the treatment technique
requirements would provide adequate
control for chloral hydrate. In the 1994
proposal, chloral hydrate was
considered a group C, possible human
carcinogen. Since the 1994 proposal,
several new studies have been
published which contribute to the
weight of evidence conclusion for the
potential carcinogenicity of chloral
hydrate. These include in vitro cell
transformation and genotoxicity studies
(Gibson et al., 1995; Adler, 1996; Allen
et al., 1994; Parry et al., 1996; and Ni et
al., 1996). Some screening studies were
found concerning the potential of
chloral hydrate to cause reproductive
and developmental toxicity (Klinefelter
et al., 1995 and Saillenfait et al., 1995).
The available new studies mentioned
above do not indicate a change in the
MCLG for chloral hydrate.
6. Bromate
The proposed rule included an MCL
of 0.010 mg/L and an MCLG of zero for
bromate. A major issue in the proposal
was that setting an MCL at 0.010 mg/L
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Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
59397
would exceed the theoretical 1x10 ~4
lifetime excess cancer risk level for
bromate of 5 ug/L. Since the proposal,
several toxicology studies have been
completed on bromate, including assays
for reproductive and developmental
effects (Wolfe and Kaiser, 1996).
USEPA has recendy completed a
chronic cancer study in male rats and
male mice for bromate. USEPA is
evaluating this data and will provide an
opportunity for public comment on die
potential implications for the regulatory
provisions for bromate prior to die final
rule.
D. Summary of Key Observations
Since the proposal, several
epidemiology and toxicology studies
have been completed on the potential
health effects associated with exposure
to DBPs. USEPA currenfly believes die
new published data will not impact die
MCLGs for BDCM, CDBM, bromoform,
chloral hydrate, or trichloroacetic acid.
However, USEPA is currendy evaluating
the results from new toxicology studies
for chlorite and bromate and will
evaluate the report from the ILSI expert
panel on chloroform and DCA when it
becomes available. USEPA will provide
an opportunity to comment on the
potential implications for die regulatory
provisions for these DBPs prior to die
final rule.
E. Request for Public Comments
USEPA requests comment on all die
new information oudined above and its
potential impacts on die regulatory
provisions for die final Stage 1 DBPR
and any additional data on the health
effects from DBPs that need to be
considered for die final Stage 1 DBPR.
III. Enhanced Coagulation and
Enhanced Softening
A. 1994 Enhanced Coagulation and
Enhanced Softening Proposal
As discussed above, the 1994
proposed rule for D/DBPs included
enhanced coagulation/enhanced
softening requirements in addition to
maximum contaminant levels (MCLs)
for total trihalomethanes (TTHMs) and
the sum of five haloacetic acids (HAAS)
(USEPA, 1994b). In diat proposal,
Subpart H systems (utilities treating
eidier surface water or groundwater
under the direct influence of surface
water) diat use conventional treatment
(i.e., coagulation, sedimentation, and
filtration) or precipitative softening
would be required to remove DBF
precursors by enhanced coagulation or
enhanced softening. The removal of
total organic carbon (TOC) would be
used as a performance indicator for DBF
precursor control. The 1994 proposed
rule (in "Step 1" of the treatment
technique) provided for 20-50 percent
TOC removal, depending on influent
water quality (Table III-l).
TABLE 111-1.—1994 PROPOSED REQUIRED REMOVAL OF TOC BY ENHANCED COAGULATION/ENHANCED SOFTENING FOR
SURFACE-WATER SYSTEMS" USING CONVENTIONAL TREATMENT13
Source-water TOC, mg/L
>20— 40
>4 0-8,0
>8.0
Source-water alkalinity, mg/L as CaCO3
0-60
(percent)
40.0
45.0
50.0
>60-120
(percent)
30.0
35.0
40.0
>120°
(percent)
20.0
25.0
30.0
•Also applies to utilities that treat groundwater under the influence of surface water.
i-Systems meeting at least one of the conditions in Section 141.135(a)(1)(iHiv) of the proposed rule are not required to operate with enhanced
coagulation.
«Systems practicing precipitative softening must meet the TOC removal requirements in this column.
The 1994 Stage I Federal Register
notice proposed diat systems achieve a
percent TOC removal based on their
influent TOC concentration and
alkalinity. The proposed rule provided
for a number of exceptions to the
enhanced coagulation and enhanced
softening requirements, namely: (a)
When the system's treated water TOC
concentration, prior to die point of
continuous disinfecdon, is 52.0 mg/L (b)
when die PWS's source water TOC
level, prior to any treatment, is <4.0
mg/L; die alkalinity is >60 mg/L; and
these systems are achieving TTHMs
<0.040 mg/L and HAAS <0.030 mg/L, or
have made irrevocable financial
commitments to technologies that will
meet these levels; (c) die PWS's TTHM
annual average is no more than 0.040
mg/L and die HAAS annual average is
no more dian 0.030 mg/L and die
system uses only chlorine for
disinfecdon; and (d) PWSs practicing
softening and removing at least 10 mg/
L of magnesium hardness (as CaCOs),
except those diat use ion exchange, are
not subject to performance criteria for
die removal of TOC.
As part of the enhanced coagulation
requirements, die proposed rule
indicated that if a PWS could not meet
die prescribed TOC removal criteria, it
must perform a series of jar or pilot-
scale tests ("Step 2") to determine how
much TOC removal they can reasonably
and practically achieve. This Step 2
requirement was created to handle the
10 percent of die waters that were not
expected to meet die Step 1 criteria, and
considerations as to what was practical
to achieve involved a consensus-based
balancing of policy and scientific
perspectives.
The proposed jar-testing protocol
involves adding regular-grade alum in
10 mg/L increments (or an equivalent
amount of iron coagulant) until specific
depressed pH goals are achieved (this
was referred to as "maximum pH" in
die proposal), which depends on
influent alkalinity and what is practical
to achieve. For the alkalinity ranges 0-
60, >60-120, >120-240, and >240 mg/L
as calcium carbonate (CaCOs), the
maximum pH values are 5.5, 6.3, 7.0,
and 7.5, respectively. The maximum pH
is a target pH goal for step 2 testing. The
maximum pH is die pH value the tested
water must be at or below before
incremental coagulant addition is
discontinued. The protocol was based
on alum, as more data were available on
the use of this coagulant in a wide
variety of waters. However, the
proposed rule allows for die use of iron
coagulants in the step 2 jar testing.
The TOC of each jar-treated water is
measured, and dien the residual TOC is
plotted versus alum dosage. The "point
of diminishing returns" (POOR) is
determined to be when 10 mg/L of
additional alum (or an equivalent
amount of iron coagulant) does not
decrease residual TOC by 0.3 mg/L (i.e.,
slope of TOC versus alum dosage curve
S[0.3 mg/L TOC]/[10 mg/L alum]).
These data would be used by a utility
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59398 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
to request alternative TOC removal
performance criteria from the primacy
agency. However, one of the intents in
setting the step 1 TOC removal
percentages at the values chosen was to
provide that 90 percent of the systems
would not need to do step 2 testing.
This would minimize transactional
costs for the primacy agencies.
If the TOC removal curve never met
the slope criterion at any coagulant
dose, such a water would be considered
unamenable to enhanced coagulation
and no TOC removal would be required
for such a water. Waters with low TOC
and moderate-to-high alkalinity were
expected to be some of the more
difficult to treat with enhanced
coagulation, so systems treating such
waters were encouraged to explore
alternative technologies (e.g., ozone/
chloramines) that could reduce DBF
levels significantly below the proposed
Stage 1 MCLs (i.e., <50 percent of the
proposed Stage 1 MCLs).
EPA solicited comments on all
aspects of enhanced coagulation's step 2
protocol in the preamble to the rule, as
well as on the step 1 TOC removal
percentages including:
(1) Whether the TOC removal levels
shown in Table III-l are representative
of what 90 percent of systems required
to use enhanced coagulation could be
expected to achieve with elevated, but
not unreasonable, coagulant addition?
(2) Whether filtration should be
required as part of the bench-pilot-scale
procedure for determination of Step 2
enhanced coagulation? If so, what type1
of filter should be specified for bench-
scale studies?
(3) Whether a slope of 0.3 mg/L of
TOC removed per 10 mg/L of alum
should be considered representative of
the point of diminishing returns for
coagulant addition under Step 2?
Comments were also solicited on how
the slope should be determined (e.g.,
point-to-point, curve-fitting); and if the
slope varies above and below 0.3/10,
where should the Step 2 alternate TOC
removal requirement be set—at the first
point below 0.3/10?, at some other
point?
(4) How often bench- or pilot-scale
studies should be performed to
determine compliance under step 2?
Should such frequency and duration of
testing be included in the rule or left to
guidance (i.e., allow the State to define
what testing would be needed on a case
by case basis for each system)? Is
quarterly monitoring appropriate for all
systems. What is the best method to
present the testing data to the primacy
agency that reflects changing influent
water quality conditions and also keeps
transactional costs to a minimum? How
should compliance be determined if the
system is not initially meeting the
percent TOC reduction requirements
because of a difficult to treat waters and
a desire to demonstrate alternative
performance criteria?
EPA also solicited comments on
several issues related to the enhanced
softening requirements including:
(1) 3x3 matrix: For softening plants, is
enhanced softening properly defined by
the percent removals in Table III-l in
this Notice, or by 10 mg/L removal of
magnesium hardness reported as
CaCO3?
(2) Use of ferrous salts: Can ferrous
salts be used at softening pH levels to
further enhance TOC removals?
(3) Step 2: Whether data are available
on the use of ferrous salts in the
softening process which can help define
a step 2 for softening? What is the
definition of Step 2?
B. New Information on Enhanced
Coagulation and Enhanced Softening
since 1994 Proposal
Since the 1994 proposal, there has
been considerable research on a number
of enhanced coagulation and enhanced
softening issues highlighted above in a
wide variety of waters nationwide. A
summary of the results of some of the
studies and surveys are included below.
Studies of enhanced coagulation are
covered first, followed by discussion of
enhanced softening studies. Note that a
number of the softening studies looked
at TOC removal in essentially the same
framework as is used for enhanced
coagulation, with emphasis on the
coagulant and lime dose and geared
toward finding a similar format for step
2 enhanced softening as was defined for
enhanced coagulation. A number of
these studies focused on the benefits of
increased lime or coagulant doses in
removing TOC in softening systems.
Results of these studies generally
showed that percent TOC removal is
dependent on the raw water.
1. New Data on Enhanced Coagulation
a. UNC Enhanced Coagulation Study.
To address many of the aforementioned
issues, the University of North Carolina
(UNC) at Chapel Hill, with funding from
the Water Industry Technical Action
Fund (WITAF), performed an enhanced
coagulation study (Singer et al., 1995).
The UNC research team evaluated a
wide range of waters nationwide, which
included at least three waters in each
box of the 3x3 matrix in Table III-l.
Each water was jartested in order to
determine the feasibility of achieving
the proposed step 1 TOC percent
removal requirement for each water, as
well as to assess the PODR criteria.
In addition, recognizing that
coagulation primarily removes the
humic fraction of the natural organic
matter (NOM) in water (Owen et al.,
1993), a determination of the percent
humic content was made for each of the
waters studied in order to better
characterize the treatability of each
water. NOM fractionation was
performed on samples of each raw water
and on select coagulated waters using
an XAD-8 resin adsorption procedure
(Thurman & Malcolm, 1981). In this
procedure, the hydrophobic fraction of
the water, which includes humic
substances, was determined.
Furthermore, Edzwald and Van
Benschoten (1990) have found the
specific ultraviolet absorbance (SUVA)
of a water to be a good indicator of the
humic content of that water, so SUVA
was also determined in the UNC study.
SUVA is defined as the UV (measured
in m-1) divided by the dissolved
organic carbon (DOC) concentration
(measured as mg/L). Typically, SUVA
values <3 L/mg-m are representative of
largely nonhumic material, whereas
SUVA values in the range of 4-5 L/m-
mg represent mainly humic material
(Edzwald & Van Benschoten, 1990).
Figures III-l and III-2 represent a
typical set of jar test results from the
UNC study. In these tests, water from
Raleigh, NC, with a TOC of 7.5 mg/L
and alkalinity of 17 mg/L was evaluated
(White et al., 1997). At low alum doses
(<20 mg/L), an initial TOC (and
turbidity) plateau was observed for
which no removal of TOC (or turbidity)
occurred with the coagulant addition.
Following the addition of a "threshold"
alum dose (20 mg/L), a steep drop in the
concentration of TOC (and turbidity)
was observed with increases in alum
dose. As the alum dose increased
further, the drop in TOC (and turbidity)
decreased to a final plateau at which
little to no additional removal of TOC
(or turbidity) was seen with further
increases in alum dose (>40 mg/L).
BILLING CODE 6560-50-P
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59399
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59400
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
1/6ui - OO1
BILLING CODE 6560-50-C
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59401
In the jar tests of the Raleigh water, an
alum dose of-3 5 mg/L resulted in the
removal of-47 percent of the TOC,
where the proposed step 1 TOC removal
for this water was predicted to be 45
percent The PODR, based on the slope
criterion of 0.3 mg/L TOC/10 mg/L of
alum, was realized at ajar-test alum
dose of 39 mg/L, in which 51 percent of
the TOC was removed. In order to
comply with a 45-percent TOC removal
requirement with a 15-percent safety
factor (Krasner et al, 1996), a system
would need to design for a 52-percent
TOC removal.
The results using the Raleigh water
appear to address several of the
outstanding issues: namely, that the step
1 TOC removal requirements for this
water is appropriate, the slope criterion
did identify the PODR, and evaluation
of the PODR required an examination of
points beyond the threshold coagulant
dose. Figure III-3 shows jar test results
for a low-TOC (2.9 mg/L), high-
alkalinity (239 mg/L) water from
Indianapolis, IN, from die UNC study
(White et al., 1997). The TOC removal
curve never exceeded the 0.3/10 slope
criterion, which means that this water
would be exempt from the enhanced
coagulation requirements in the 1994
proposed rule. The step 1 TOC removal
requirement of 20 percent can be
achieved, with an alum dose of -65 mg/
L required in the jar tests. However, the
slope of the TOC removal curve shows
that this water is not very amenable to
enhanced coagulation.
BILLING CODE 6560-50-P
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59403
A summary of the controlling
criterion for each of the 31 waters tested
by UNC. based on the 1994 proposed
rule criteria, is shown In Table III-2
(adapted from White et al., 1997). Only
14 of the 31 waters met the proposed
step 1 percent TOC removal
requirements or achieved a settled water
TOC concentration <2.0 mg/L at an
alum dose less than or equal to that
needed to meet the PODR. Those waters
that readily met the step 1 TOC removal
requirements were mostly moderate-to-
high-TOC waters with low alkalinity.
The UNC study suggested that a
significant number of waters (especially
low-TOC, high-alkalinity waters) would
probably need to use the step 2 protocol
to establish alternative performance
criteria.
TABLE III-2.—CONTROLLING CRITERION FOR ENHANCED COAGULATION FOR WATERS EVALUATED IN UNC STUDY, BASED
ON 1994 PROPOSED RULE CRITERIA
Source-water TOC, mg/L
>2 0-4.0
>40-80
>80
0-60
<2.0»
PODR
PODR
PODR
PODR
STEP 1
STEP 1
STEP 1
STEP 1
STEP1
POOR
>60-120
PODRb
PODR
STEP 1 <"
PODR
PODR
PODR
STEP 1
STEP1
STEP 1
PODR
STEP1
>120
N/A<=
PODR
N/A
STEP 1
STEP 1
PODR
STEP 1
PODR
PODR
Source-water alkalinity, mg/L as
CaCO3
"Settled water TOC less than 2.0 mg/L.
bPoW of diminishing returns.
"Not amenable to enhanced coagulation.
dStep 1 required percent removal of TOC.
White and co-workers (1997)
examined the relationship between the
percent humic (hydrophobic) content of
the raw waters in the UNC study and
the maximum percent removal of DOC
achieved at the high alum doses where
little additional TOC removal was
observed. Figure III-4 shows that waters
with relatively high levels of humic
material tended to exhibit higher
degrees of DOC removal than those with
low humic content. Figure III-5 shows
that waters that contained high initial
nonhumic (hydrophilic) DOC
concentrations tended to have high
residual DOC concentrations following
coagulation.
BILLING CODE 6560-50-P
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59404
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
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Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
59405
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-------
59406 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
In the UNC study, the humic carbon
content of the raw waters was
reasonably correlated (r2=0.74) with
their SUVA values (White et al., 1997).
Figure III-6 shows that waters with high
initial SUVA values (i.e., 3.4-5.7 L/mg-
m) exhibited significant reductions in
SUVA as a result of coagulation,
reflecting substantial removal of the
humic (and other UV-absorbing)
components of the overall organic
matter, whereas waters with low initial
SUVA values (i.e., 1.5-2.0 L/mg-m)
exhibited relatively low reductions in
SUVA. For all of the waters examined,
the residual SUVA (i.e., <2A L/mg-m)
tended to plateau at high alum doses,
reflecting that the residual DOC was
primarily nonhumic organic matter.
BILUNG CODE 6560-50-P
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59408
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
In the UNC study, for the 14 waters
in which the step 1 TOC removal
requirements were met before the PODR
was reached, the average raw-water
SUVA was 3.9 L/mg-m, whereas the
average raw-water SUVA of the other 17
waters was 2.6 L/mg-m (White et al.,
1997). For most of the 31 waters
examined, the PODR was found to occur
at alum doses where SUVA had already
reached its plateau. These findings
suggested that raw-water SUVA values
might be utilized in redefining the step
1 TOC removal requirements and that
residual SUVA values might be utilized
in defining the PODR. Unlike NOM
characterizations with XAD resins in a
research laboratory, SUVA is an easy
parameter that can be determined by
laboratories that measure DOC
concentrations and UV absorbance.
fa. Metropolitan Water District of
Southern California/Colorado
University Enhanced Coagulation
Study. As noted in the UNC study,
waters with low TOC and high
alkalinity were expected to be the more
difficult to treat with enhanced
coagulation. Metropolitan Water District
of Southern California (MWDSC) and
Colorado University at Boulder did
detailed studies on two low-TOC
waters, one with moderate alkalinity
(California State Project Water) and the
other with high alkalinity (Colorado
River water). In addition to using an
XAD-8 resin fractionation to quantify
the humic (hydrophobic) versus
nonhumic (hydrophilic) content of the
NOM, a 1000-dalton (IK) ultrafilter was
used to determine what fraction of the
bulk or coagulated water was of a lower
versus higher molecular weight (Amy et
al., 1987).
California State Project Water (with 80
mg/L alkalinity) was jar-treated with
incremental alum doses of ~ 622 mg/L
(up to a total of 111 mg/L). Figures III-
7 and III-8 show that addition of alum
at 47 mg/L reduced the raw-water bulk
DOC concentration from 4.3 mg/L to 2.6
mg/L (a 39-percent bulk DOC removal);
subsequent alum addition resulted in a
plateauing of the DOC removal rate
(Krasneret al., 1995). Throughout the
entire range of alum doses evaluated,
little of the low-MW and nonhumic
DOC was removed. The high-MW and
humic fractions, however, were well
removed with increasing alum dosages,
demonstrating preferential removal of
these fractions. The residual DOC
remaining after enhanced coagulation
was primarily made up of low-MW and
nonhumic material. The latter NOM
fractions represent the part of the bulk
DOC that is not readily amenable to
removal by coagulation.
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59409
ecular Weight
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59410 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
t/3
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BILLING CODE 6560-50-C
-------
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules 59411
For this sample of California State
Project Water, 52 percent of the DOC
was humic NOM and the SUVA value
was 2.5 L/mg-m (Krasner et al., 1995).
Figure 1II-9 shows that increasing doses
of alum reduced the fraction of humic
DOC in the residual DOC to 26 percent.
In addition, die reduction in SUVA
closely paralleled the reduction in die
humic content of die residual DOC.
SUVA was reduced to 1.7 L/mg-m with
47 mg/L of alum, whereas the addition
of 111 mg/L of alum only reduced the
value of SUVA to 1.5 L/mg-m.
BILLING CODE 6580-W-P
-------
59412 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
raction of Humic DOC in
Figure OI-9: Impact of Increased Alum Dose on SUVA and F
SPW
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BILLING CODE 6660-50-C
-------
Federal Register / Vol. 62. No. 212 / Monday, November 3, 1997 / Proposed Rules 59413
raw-water Colorado River water had a
SUVA value of 1.1 L/mg-m and 44
percent of the DOC was humic NOM.
After the addition of 114 mg/L of alum,
the humic content of the residual DOC
was only reduced to 38 percent and the
SUVA value was only reduced to 1.0 L/
mg-m (Figure 111-12).
Colorado River water has a greater
amount of low-molecular weight DOC
and somewhat more nonhumic DOC
than California State Project Water
(Krasneret al.. 1995). Nonetheless,
Increased doses of alum did remove
DOC in Colorado River water, although
not to the same extent as in California
State Project Water. Although the
alkalinity of Colorado River water (135
mg/L) is higher than that of California
State Project Water, the difference in
treatability was more likely related to
the differences in the NOM
characteristics of the two waters. As
with California State Project Water, the
residual DOC in the coagulated
Colorado River water was primarily
low-molecular weight and nonhumic
NOM (Figures HI-10 and III-l 1). The
BILLING CODE 0560-50-P
-------
59414
Federal;Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
s
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-------
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
59415
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-------
59416 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
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-------
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
59417
Chang and co-workers (1995) studied
enhanced coagulation of California State
Project Water and Colorado River water,
as well as the effects of seasonal changes
on TOC removal. Several water blends
\vere tested, including 100-percent
California State Project Water and
Colorado River water, as well as 90-,
80-. 70-, 60-, and 50-percent Colorado
River water blends. These blends
represent the range of waters that are
treated at MWDSC's plants and may be
subject to enhanced coagulation
treatment. The SUVA values for
California State Project Water during
this study ranged from 2.8 to 3.8 L/m-
mg, whereas the SUVA values for
Colorado River water varied from 1.0 to
1.7 L/m-mg (the blends of California
State Project Water and Colorado River
water contained SUVA values of <3.0 L/
m-mg),
Cheng and co-workers (1995) also
addressed the issue of curve fitting to
examine the TOC removal curves. All
data were analyzed by fitting to eitiier
an exponential decay-type equation, a
third-order polynomial-fit equation or to
an isopleth-type equation. The data fit
best when the curve-fitting started after
the "threshold" coagulant dose, and this
is consistent with the finding of the
UNC group (discussed in section La.
above). When the data are fitted to a
100-percent California State Project
Water water during October 1993
(Cheng et al., 1995) the data did not fall
Into an isopleth or exponential-type
curve, but rather a third order equation
fit. The third order equation fit the data
with a very high correlation coefficient,
but it smoothed the curve and masked
the actual slope of the removal curve.
The results from Cheng and co-
workers indicate that a single model
could not adequately fit all the data sets
(data below the threshold coagulant
dose had to be omitted), nor could it fit
all the waters tested during various
seasons. MWDSC's data better fit the
decay-type or polynomial-fit equation
than the isopleth, but the isopleth
yielded the PODR TOC removal
percentages that best matched those of
die point-to-point mediod for all
samples, and better matched the TOC
removal curve.
c. Malcolm Pirnie, Inc./Colorado
University data collection and analysis.
The UNC/AWWA enhanced coagulation
provided substantial new information
and addresses some of the outstanding
issues raised above, but also raised
concern over the number of systems that
might seek alternative performance
criteria. In order to evaluate the number
of systems that may seek alternative
treatment and to develop data to
support revisions to the proposed
requirements, Malcolm Pirnie, Inc. and
Colorado University, with funding from
the Water Industry Technical Action
Fund (WITAF), performed a data
collection and analysis project to collect
additional data on enhanced
coagulation.
Because the Malcolm Pirnie, Inc./
Colorado University team assembled
enhanced coagulation data from
numerous researchers throughout the
country, some source waters were tested
more than once. If a source water was
studied more than once (e.g., Colorado
River water), but had similar water
quality over time (e.g., comparable TOC,
SUVA, alkalinity), the results of the
different experiments were averaged so
as to not have the database overly
influenced by a few water types. On the
other hand, if the same source water
was evaluated, but the water quality was
different, then each experiment was
separately considered. In some cases, a
source water moved from one box in the
3x3 matrix to another with variations in
TOC and/or alkalinity. If the identical
sample of water was evaluated with
different coagulants, both sets of data
were included as separate entries. It is
important to note that a number of
systems have started to not only
enhance their coagulation process, but
have switched the type of coagulant
they are using to one that improves TOC
removal.
Table III-3 provides a summary of die
raw-water characteristics of the 127
waters in the Malcolm Pirnie, Inc./
AWWA database. When waters in this
nationwide database were examined by
raw-water TOC, SUVA, and alkalinity,
researchers observed that high-TOC (>8
mg/L)/low alkalinity (<60 mg/L) waters
had high SUVA (median = 4.9), whereas
low-TOC (2-4 mg/L)/high-alkalinity
(>120 mg/L) waters had low-SUVA
(median = 1.7). For the entire 3x3
matrix, the cumulative probability
distribution (10th, 50th, and 90th
percentile) of SUVA values typically
increased with either increasing TOC or
decreasing alkalinity. Because SUVA is
an indication of humic NOM content,
and it is the humic fraction that is most
amenable to enhanced coagulation, this
SUVA distribution supports the earlier
observation of the UNC research team
that step 1 TOC removals were most
readily met in high-TOC waters with
low alkalinity.
BILLING CODE 6560-50-P
-------
59418 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
I
Ed
I
1
I
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H
s!
S3
1
s
N
A
3
3
in
3
BILLING CODE 6660-50-C
-------
Federal Register / Vol. 62. No. 212 / Monday, November 3, 1997 / Proposed Rules 59419
From this database, the Colorado
University research team (Edwards,
1997; Tseng & Edwards, 1997)
developed a model for predicting
organic carbon removal during
enhanced coagulation, using as input
the coagulant dose, coagulation pH,
raw-water UV absorbance, and raw-
water DOC concentration. The model
assumes that all DOC can be divided
into two distinct fractiqns (Figure III-
13): DOC that strongly complexes
hydroxide surfaces formed during
coagulation and DOC that does not
(Edwards et al., 1996). Edwards defined
these fractions as sorbing and
nonsorbing DOC, respectively. In the
model, the relative fraction of sorbing
and nonsorbing NOM is calculated
using an empirical relation based on the
value of SUVA (Edwards, 1997).
BILLING CODE 6SSO-60-P
Figure HI-13: Basic conceptualization of two hypothetical DOC fractions in natural waters.
= Non Sorbing DOC
¥
- Sorbing DOC
Basic conceptualization of two hypothetical DOC fractions in natural waters.
The sorbing DOC fraction is in equilibrium with sorbent hydroxide formed during
coagulation.
Edwards, M. 1997. Reprinted from Journal AWWA, Vol. 89, No.5 (May 1997), by permission.
Copyright ©1997, American Water Works Association.
BILLING CODE U40-SO-C
In the Colorado University modeling
effort (Edwards, 1997), the best
predictive capability was provided by a
site-specific approach using a best-fit
sorption constant and nonsorbing DOC
fraction for each water quality and
coagulant type (Figure IH-14).
Assuming a typical DOC analytical error
of either ±0.25 mg/L or ±5 percent, 81
percent of the model predictions were
accurately predicted within analytical
precision.
BILLING CODE 6C60-60-P
-------
59420 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
Figure m-14: Actual percentage of DOC removal versus model prediction for DOC model
80
1
.. • Model Error Within Analytical Precision
+ Model Error Exceeds Analytical Precision
40t
0
20
40
60
80
Predicted % DOC Removal
Actual percentage DOC removal versus model prediction for DOC model calibrated using a site
specific sorption constant and non-sorbing DOC fraction. Only 19% of all model predictions exceeded
expected error in calculating %DOC removal of either ± 0.25 mg/L or ± 5%, whichever is greater
Edwards, M. 1997. Reprinted from Journal AWWA, Vol. 89, No.5 (May 1997), by permission.
Copyright ©1997, American Water Works Association.
BILLING CODE 6560-SO-C
The Colorado University DOC/SUVA
model was subsequently used to
determine the "maximum" TOC
removal that can be achieved with
enhanced coagulation. All nine boxes in
the 3x3 matrix (Table III-3) Were
evaluated using the 10th, 50th, and 90th
percentile water qualities.-The model
was used to determine the amount of
sorbable TOC and to examine removal
of 100, 90, 80, 70, 60, and 50 percent of
the sorbable TOC.
Table III-4 summarizes the results
from the maximum TOC removal task.
A 10th percentile SUVA value
corresponds to a water that is difficult
to treat (relative to other waters in that
same box), whereas a 50th and 90th
percentile SUVA value corresponds to
waters that are average and easy to treat,
respectively, in that box. The sorbable
amount of TOC represents the
maximum amount of TOC that can be
removed using coagulants with no limit
on coagulant dosage. Therefore, these
values may not be practical or realistic
to achieve. In Table III-4, the 1994
proposed Step 1 TOC removal
requirements are listed, along with a 15
percent safety factor. For example, in
the low-TOC, low alkalinity box, the
current Step 1 TOC removal
requirement (40 percent) with a safety
factor is 46 percent. In this box, for an
easy to treat water (90th percentile
SUVA of 3.97), 62 percent of the
sorbable TOC would need to be
removed to ensure compliance with the
proposed requirement; whereas for a
difficult to treat water (10th percentile
SUVA of 2.84), 71 percent of the
sorbable TOC would need to be
removed.
BILLING CODE 6560-50-P
-------
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
59421
TABLE IH-4: Prediction of "Maximum" TOC Removal Based on Colorado University
DOC/SUVA Model
Pertentile
10th
50th
90th
10th
50th
90th
10th
50th
90th
PerCtntile
10th
50th
90th
10th
50th
90th
I Oth
50th
90th
Percentllc
10th
50th
90th
10th
56th
90th
10th
50th
90th
roe
>2-4
>4-8
>8
'••"<:>..•. "• •'• ..• •••;' ,. Alkalinity -Or«0 mg/L : ' • .-, .:•• -••"•', .'?
•$l*
2.84
3.38
3.97
2.38
329
4.79
4.33
4.86
5.54
•• t-' • joe-f^^vif^^^f^^^Mm^^^
;;(10&%J!,
65
69
74
62
69
80
76
80
86
:0>0%)r
59
62
67
56
62
72
68
72
77
:$8fl|%^
52
55
59
50
55
64
61
64
69
^T^Ji
46
48
52
43
48
56
53
56
60
l&Qiffl®
39
41
44
37
41
48
46
48
52
*:(50%3|i
33
35
37
31
35
40
38
40
43
.TOC
, mg/L
>2-4
>4-8
>8
TOC
mg/L
>2-4
>4-8
>8
-s x v 4 ' Alkalinity >tiO»120> mg/L „ ,
SUVA
2.03
2.73
3.09
1.93
2.48
3.83
3.80
4.15
4.49
TOC Removal <% Sqrbible TOC Removed)
(100%)
59
64
67
58
63
73
73
75
78
(90%)
53
58
60
52
57
66
66
6.8
70
.(80%)
47
51
54
46
56
58
58
60
62
(70%)
41
45
47
41
44
51
51
53
55
(60%)
35
38
40
35
38
44
44
45
47
(Sfi%)
30
32
34
29
32
37
37
38
39
:. Step,!-
life
40
40
40
45
45
45
SO
50
50
Rem.
30
30
30
35
35
35
40
40
40
t Alkalinity >120 mg/L •- l >
SUVA
1.43
1.74
3.68
1.64
1.9d
3.01
2.22
2.60
3.17
-' TOQ. Removal (%Sorfaablf TOC Removed)
000%)
55
57
72
56
58
67
61
64
68
(90%)
50
51
65
50
52
60
55
58
61
(80%)
44
46
58
45
46
54
49
51
54
(?0%)
39
40
50
39
41
47
43
45
48
(60%)
33
34
43
34
35
40
37
38
41
(50%)
28
29
36
28
29
34
31
32
34
Rent.
20
20
20
25
25
25
30
30
30
Step 1 TOG;
. Rent*;.;, :
46
46
46
52
52
52
58
58
58
step i
TOC Rent.
+15%
35
35
35
40
40
40
46
46
46
Step!
TOC Rem.
+15%
23
23
23
29
29
29
35
35
35
:%SorD. TOC:;:
'" •'.' •':•' '•'. .••'.''•
71%
67%
62%
83%
75%
65%
76%
72%
67%
%SDrt»« |OC
item.; Meet
Stepl*lS%
58%
54%
51%
69%
64%
55%
63%
61%
59%
%Sorb. TOC
Rem.; Meet
Stepl +!$*/.
42%
' 40%
32%
51%
50%
43%
57%
54%
51%
BILLING CODE (MO-80-C
The next analyses evaluated what
TOC removal Is "practical" to achieve
In order to better define the 3x3 matrix.
The data analyses were aimed at
developing an alternative set of percent
TOC removal numbers for step 1
requirements, recognizing that the goal
was to select values that could be
"reasonably" met by 90 percent of the
systems implementing enhanced
coagulation. Using the database
compiled through the Malcolm Pirnie,
Inc./AWWA project and summarized in
Table III-3, the following nine equations
were developed to predict "90th-
percentile" TOC for a given coagulant
dose. Figure 111-15 illustrates the shape
of the curves for the low-alkalinity
waters.
BILLING CODE 6580-M-P
-------
59422
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
Figure ffl-15: TOC Removal Models for Low Alkalinity Waters
TOC
.5 -
3n -
"•^ ft C
O) * •"
20-
o 1-s
•~ 1 0 -
0^ -
On -
Removal Models for Low Alkalinity Waters
X.
>x.
4
^
1
^r
s»
T
— ri
0.00 0.10
C o a
7 n j-
6.0 -
*""?• *\ n
* !o
E 4 -0 "
O 3 .0 -
o
1f\ -
\.
X.
^s
1
g
K^
*>
ix.
0 C = 1 .42 + 2.04 e -r-1s*D°»«
(Alkalinity: 0 to (0 m all, TOC 2 to 4
»
— -»_ 1
- M
m 8/L)
; r " """ ' ~
0.20 0.30 0.40 0.50 0.60
ulant Dose (m m oles/L)
1
TOC»1.6 + 5.38e •8'29'
(Alkallnlty:0 to60mg/L,TOC4to»m
is
0.00 0.10
C o a
30.0
25.0
o> 20>0
O
O 10.0
5.0
0.0
0
4
• ^-^
g
g^-.
^
r — ,.
4
f' *""—,
Dose
g'H
r^ ±
0.20 0.30 0.40 0.50 0.60
ulant Dose (m m o le s /L )
»
'"^*««.
TO C - 3.22 + 23.1 e •2'99"
{Alkalinity: 0 lolOmgtL,TOC>tmgl
•^
•*»*
r
^ _
*
*^^
Dos*
«•)
^ i^
.00 0.10 0.20 0.30 0.40 0.50 0.60
C o ag u la n t D os e (mmoles/L)
BILLING CODE 6560-5O-C
-------
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
59423
The significance of the 90th-
percentlle data point is that 90 percent
of systems (represented by the database)
will have a lower residual TOG
compared to what is predicted by the
equations for a given coagulant dose.
1. TOO1.42+2.04 • e ~7-ls • V0** oi«/L)
[for low-TOC, low-alkalinity box]
2. TOC-1.37+2.10 • e ~3M • D™0 <«noIej/L>
[for low-TOC. medium-alkalinity
box]
3. TOC-2,10+1.27 • e ~2-73 • Dosc (=»!««-)
[for low-TOC, high-alkalinity box]
4. TOC-1.60+5.38 • e -"9 • DMC Onoies/L)
[for medium-TOC, low-alkalinity
box]
5. TOC-2.11+4.41 • e ~3-47 • D"" (molest)
[for medium-TOC, medium-
alkalinity box]
6. TOC=>2.64+3.30 • e ~4-83 • Dt>5C fr"*^)
[for medium-TOC, high-alkalinity
box]
7. TOC=3.22+23.1 «6 -2.99.Dose (moles/L)
[for high-TOC, low-alkalinity box]
8. TOC=4.88+13.8 • e ~3-33 • Dose (moics/L)
[for high-TOC, medium-alkalinity
box]
9. TOC=6.61+6.44«e -S.ST.DOSC (molest)
[for high-TOC, high-alkalinity box]
Based upon the above equations, the
coagulant dosages for achieving the
proposed percent TOC removals and the
proposed PODR slope criterion (i.e., 0.3
mg/L TOC per 10 mg/L of alum) were
calculated. These calculations indicated
diat the low-TOC boxes will be at the
proposed slope criterion at coagulant
dosages lower than what would be
required for achieving the proposed step
1 percent TOC removals. The opposite
was true for the high-TOC boxes. For the
medium-TOC boxes, the calculated
coagulant dosages were approximately
equal for both criteria. The trends for
the different boxes in the matrix are
similar to that observed by the UNC
research team (Table III-2). Table III-5
summarizes the controlling criteria.
TABLE 111-5.—CONTROLLING CRI-
TERION FOR ENHANCED COAGULA-
TION FOR WATERS EVALUATED IN
MALCOLM PIRNIE, INC. STUDY,
BASED ON MODELING APPROACH
TOC (mg/L)
>2.0-4.0
>4.0-8.0
>8.0
Alkalinity mg/L
0-60
PODR
Stepl
Stepl
>260-
120
PODR ....
PODR ....
Stepl ...
>120
PODR
Stepl
Stepl
Malcolm Pirnie. Inc. next examined
SUVA removal curves (Figure 111-16),
similar to what was examined by the
UNC research team (Figure III-6).
BILLING CODE 6S80-SO-P
-------
59424
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
Figure ffl-16: SUVA Removal Models for Low TOC Waters
SUVA Removal Models for Low TOC Water
.0 '
.5 -
3 .0 -
< 2.5 -
Jg 2 .U
'CO -ic
* 1 .5 -
1 .0 -
0.5 -
N^
^^^^
0.0 4
0.00
3.5 -
3.0 '
2.5 -
1 2"° '
CO 1-5 -
1.0 -
0.5 -
I
^— , ! -
*
SUVA = 1.8 + 2.1 e *11-1'00
(Alkillnlty:o to 10 m g/L, TOC 2 to 4 mg/l
«
!•
)
r — '
__-r-»
»
+
0.10 0.20 0.30 0.40 0.50 0.60
CoagulantDose (mmoIes/L)
^v%>>^
^"*"«<^j
«
0.0 4
0.00
4.0 -
~ ^ •
3.5 -
3.0 -
< 2.5 -
f> 2.0 -
1 .5 -
1 .0 -
0.5 -
1 — —»- •»
f— in n.i '
SUVA » 1.8 + 1.2 e -T-9"D01
(Alkillnlty: (0 to 120 m g/L, TOC 2 to 4 m g
f- " * 4
•
| . i ,
- - — -
0.10 0.20 0.30 0.40 0.50 0.60
Coagulant 0 ose (mmoles/L)
\
"V^
••••,
0.00
SU
. '
VA - 1.4 + 2.2 0 -9-5'D°'
killnlty > 120 m g/L, TOC 2 to 4 m g/L
0.10 0.20 0.30 0.40 0.50 0.60
Coagulant Dose (m m oles/L)
BILUNG CODE G560-SO-C
-------
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules 59425
The 90th-percentile SUVA curves
were observed to reach asymptotic
values with increasing coagulant Dose
(Figure 111-16 illustrates the shape of the
curves for the low-TOC waters). The
following seven equations were
developed to predict the 90th-percentile
SUVA for a given coagulant Dose. The
three alkalinity ranges for the high-TOC
waters were collapsed into one group
due to lack of sufficient data. Similar to
the TOG equations, the significance of
the aoth-percentile data point is that 90
percent of systems (represented by the
database) will have a lower residual
SUVA compared to what is predicted by
the equations for a given coagulant
Dose.
a. SUVA=1.8+2.1 »e -»•'•Doso (moio/i.)
[for low-TOC. low-alkalinity box)
b. SUVA-1.8+1. 2 «e -™»*x*° (moics/i.)
[for low-TOC, medium-alkalinity
box]
c. SUVA=1.4+2.2 • e ~9-5 • DoM o»«>ies/L>
[for low-TOC. high-alkalinity box]
d. SUVA=1.9+2.8 • e -17-5 • °°K Onoieia.)
[for medium-TOC, low-alkalinity
box]
e. SUVA=1.8+2.0 • e ~s-
[for medium-TOC, medium-
alkalinity box]
f. SUVA=2.1+0.95 • e ~6
[for medium-TOC. high-alkalinity
box]
g. SUVAs2.5+2.8 • e ~3-8 • °2.0-4.0
>4.0-8.0
>8.0
Alkalinity (mg/L)
0-60
35
35
60
>60-
120
25
45
55
>120
15
20
35
One limitation of a step 2 based on a
settled-water SUVA approach would be
that the utilities would have to
determine these SUVA values in the
absence of any oxidant (such as
chlorine, permanganate, or ozone).
Addition of oxidant changes the
characteristics of the NOM in a manner
that disproportionately affects the UV
absorbance compared to TOC, thus
changing the SUVA values without any
actual removal of TOC.
d. Evaluation of current (baseline)
TOC removals at full-scale. Full-scale
TOC removal data were obtained from
76 treatment plants (Table III-7). These
data were obtained from plants in the
American Water Works Service
Company (AWWSCo) system, plants
studied by Randtke et al. (1994), and
plants in North Carolina studied by
Singer et al. (1995). Note that these data
represent a one-time sampling at each
plant and no specific attempt was made
to meet the proposed TOC removal
percentages. Also, the proposed
compliance requirements were based on
an annual average. Based on current
treatment, 83 percent of the systems
treating moderate-TOC, low-alkalinity
water removed an amount of TOC
greater than the proposed step 1
requirement, whereas only 14 percent of
the systems treating water with low
TOC and high alkalinity met the
proposed step 1 requirement. For the
other systems treating low- or moderate-
TOC water, 29-38 percent met the
proposed step 1 requirements with
existing treatment. Although all of the
high-TOC systems met the proposed
TOC removal requirements with current
treatment, the number of systems in this
database were insignificant (1-2 per
box).
TABLE 111-7.—TOC REMOVAL AT FULL-SCALE TREATMENT PLANTS
TOC >2.0-4.0 mg/L
Alkalinity (mg/L)
0-60
>60-120
>120
TOC >4.0-8.0 mg/L
0-60
>60-120
>120
TOC >8.0 mg/L
0-60
>SO-120
>120
No. of
Plants
14
11
7
18
8
13
2
2
1
Stepl
TOC%
40
30
20
45
35
25
50
40
30
Percent of plants that achieve specified TOC removal
0-10%
removal
14
36
57
10-20%
removal
14
0
29
20-30%
removal
14
27
14
30-40%
removal
29
18
0
>40% re-
moval
*29
18
0
Percent of plants that achieve specified TOC removal
0-15%
removal
0
12
31
15-25%
removal
0
25
31
25-35%
removal
11
25
23
35-45%
removal
6
38
15
>45%
removal
83
0
0
Percent of plants that achieve specified TOC removal
0-20
0
0
MA
20-30
0
0
NA
30-40
0
0
100
40-50
0
0
NA
>50
100
100
NA
•Values In bold represent the percentage of systems that achieved full-scale TOC removal that is greater than the proposed step 1 require-
ments.
-------
59426
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
e. Evaluation of "optimized" TOO
removal. An "optimized" coagulation
database was assembled, utilizing
experiments performed by AWWSCo
and by Randtke et al. (1994) (Table III-
8). This database included experiments
in which a combination of coagulant
and acid was evaluated. The National
Sanitation Foundation (NSF) limit on
sulfuric acid addition (to minimize the
introduction of trace impurities present
in the acid) is 50 mg/L. In examining the
database, an attempt was made to limit
coagulant doses to -10-20 times the
TOC level. Thus, a water with 3 mg/L
TOC might use up to 30-60 mg/L of
coagulant (with or without acid), but
would not use 100 mg/L of coagulant
full-scale. However, a water with 10 mg/
L TOC could use 100 mg/L or more of
coagulant given the aforementioned
-10-20 multiplier for coagulant dose
and TOC. A dose of this magnitude is
discouraged because the NSF limits on
aluminum sulfate and ferric chloride are
150 mg/L and 250 mg/L, respectively.
Because these experiments were
performed without these acid and
coagulant dose limits as constraints,
some waters were evaluated with more
realistic chemical doses in the PODR
experiments. A judgment was made in
deciding which set of conditions was
the most realistic for each water
evaluated. With these elements in mind,
an assessment was made as to which
experiment was the most appropriate
(controlling criteria) for each water. In
some cases, a source water was tested
more than once. If the identical sample
of water (same TOC, SUVA, alkalinity)
was coagulated with different
coagulants, with or without acid, the
highest TOC removal for that water was
chosen, as many systems enhancing
their coagulation process are also
evaluating switching the type of
coagulant.
BILLING CODE 6560-50-P
-------
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules 59427
TABLE III-8: Analysis of the Optimized Coagulation Database
1 oc; Removal at "C'ontroIIing^ {Condition '
Statistic
;- •.' '", *~ .
(% w/SUVA/3.0)
(no. w/SUVA^2.0)
minimum*
25th percentile*
50th percentile*
75th percentile*
maximum*
(% w/SUVA^.0)
(no. w/SUVA,>2.0)
minimum*
25th percentile*
50th percentile*
75th percentile*
maximum*
%w/SUVAr<2.0)
(no. w/SUVA^2.0)
minimum*
25th percentile*
50th percentile*
75th percentile*
mfjxjjnurn*
TOC ,
>2-4
(mg^L)
>4-8
>8
Alkalinity (mg/L)
.0-60
(13%)
(12)**
26%
30%
39%
46%
57%
(0%)
(12)
17%
46%
54%
61%
68%
(0%)
(7)
56%
56%
68%
69%
76%
>60-t20
(0%)
(7)
16%
-25%
27%
-34%
46%
(36%)
(6**)
19%
34%
39%
43%
50%
(0%)
(2)***
65%
N/A
68%
N/A
72%
„ >120, ,
(64%)
(5)
2%
17%
20%
22%
28%
(57%)
(2**)
10%
N/A
N/A
N/A
44%
(0%)
(4)
37%
N/A
44%
N/A
61°4
'Cumulative probability distribution for waters with SUVA,>2.0.
**Number of waters with SUVAp»2.0, excluding waters evaluated w/aoid dose>NSF limit.
***Same source water.
BILLING CODE tMO-50-C
-------
59428
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
f. "Case-by^case" data analyses. A
decision was made by the TWG, based
on the Malcolm Pirnie, Inc. modeling
effort and examination of the case-by-
case data, to segment out raw waters
with SUVA (SUVAr) <2.0 L/mg-m
during the analyses of the optimized
coagulation database. This decision was
made because including a significant
number of low-SUVA waters in the
analysis of the boxes results in lowering
the amount of TOC that 90 percent of
the systems in that box can remove.
Thus, the TWG decided to examine
what TOC removal could be
accomplished by the medium-and high-
SUVA waters that remained in each box.
Table III-8 provided a statistical
summary of all the waters in each box
of the matrix. Listed below are a
summary of the key observations:
(1) A majority of the high-alkalinity
(>120 mg/L) waters in the low (>2-4
mg/L) and moderate (>4-8 mg/L) TOC
boxes have SUVA <2.0 L/mg-m. For
many of these waters, optimized
coagulation requires very high doses of
acid or coagulant, which are not
practical to use. Many of these waters
are not readily amenable to enhanced
coagulation. However, some of the
systems that treat these waters will
incorporate some level of enhanced
coagulation in order to control DBF
formation.
(2) For the waters in which the raw-
water SUVA was >2.0 L/mg-m, the
minimum, 25th percentile, 50th
percentile, 75th percentile, and
maximum TOC removal for each of the
boxes in the 3x3 matrix were
determined. This analysis allowed for
an analysis of the cumulative
probability distribution of TOC removal
for waters that are amenable to
enhanced coagulation.
(3) For example, the high-TOC (>8
mg/L)/low alkalinity (0-60 mg/L) box
had a range of TOC removals from 56 to
76 percent. In order to comply with a 50
percent TOC removal (the proposed step
1 value for that box) with a safety factor
of 15 percent, a 57 percent TOC removal
would be required. The minimum and
25th percentile TOC removal for that
box is 56 percent Thus, it is expected
that essentially all of the waters in this
box (based on this limited data set and
data from other sources) could comply
with the proposed step 1 requirement.
(4) If the step 1 requirement for the
high-TOC/low-alkalinity box was raised,
for example, to 60 percent, then systems
would need a 69 percent TOC removal
to safely meet such a requirement. The
75th percentile of TOC removal for this
box is 69 percent. Thus, raising the step
1 requirement to 60 percent could
potentially drive half or more of the
systems in this box to need to do step
2 testing for possible alternative
performance criteria. Thus, these data
suggest that for this and a number of
other boxes (all of the high-TOC boxes
and probably most of the moderate-TOC
boxes), the currently proposed step 1
TOC removals are appropriate. Systems
that can achieve higher TOC removals
in these boxes will consider doing so in
order to more effectively meet the DBF
MCLs that have been proposed.
(5) For the low-TOC boxes, even after
excluding the low-SUVA waters, the
proposed step 1 TOC removal levels still
appear too high. In Malcolm Pirnie,
Inc."s modeling of TOC removal at
minimum SUVA + 25 percent, it was
predicted that the required TOC
removals in the low-TOC boxes would
be 35, 25, and 15 percent for low-,
moderate-, and high-alkalinity,
respectively. These predicted TOC
removal values are in the range for
which the majority of low-TOC waters
with SUVA values >2.0 L/mg-m can
achieve. Thus, the TWG recommended
to the FACA Negotiating Committee-
based on Malcolm Pirnie, Inc."s
modeling effort and this case-by-case
analysis—a revised set of TOC removal
numbers for the low-TOC boxes,
keeping in mind that low-SUVA waters
would be excluded from the
requirement.
(6) The TWG also recommended to
the FACA Negotiating Committee an
alternative step 2 point of diminishing
return (PODR) of setded-water SUVA
S2.0 L/mg-m. This action will also
reduce transactional costs, as
presentation of a settled-water SUVA
value will be easier than presenting jar-
test data. Nonetheless, the jar-test
protocol and slope criterion will still be
needed for evaluating alternative
performance criterion for other waters.
2. New Data on Enhanced Softening
a. AWWARF studies—data on TOC
removal. Several studies examined the
relationship between increased
coagulant dose and TOC removal
(Shorney and Randtke, 1996; Clark et al.
1994). These studies indicate that the
benefit from increased coagulant dose in
TOC removal was dependent on the raw
water. In a study funded by AWWARF,
Shorney and Randtke (1994) indicated
that utilities treating source water
relatively low in TOC (i.e., 2.5 to 4 mg/
L) and low in turbidity will have die
greatest difficulty in removing TOC
(Figure 111-17 and IH-18).
BILLING CODE 6S6O-SO-P
-------
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
59429
Figure m-17: The Effect of Increasing Coagulant Dosage on TOC Removal by Softening (100 mg/L
CaO) of UT6 Water
Alum
-*-
Ferric Sulfate
10 15 20 25
Ferric Sulfate Dosage, mg/L
Shomey,H. andS. Randtke. 1994. Reprinted from Proceedings of the 1994 Annual
Conference of the American Water Works, by permission, Copyright © 1994, American Water
Works Association.
-------
59430 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
I
O
CO
1
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O
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oo
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BILLING CODE 6560-50-C
-------
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
59431
The authors indicate some improved
TOG removal from small doses of iron
salts (5 mg/L ferric sulfate), but no
additional TOC removal during
softening occurred with increased
coagulant addition (up to 25 mg/L dose)
as shown in Figures 111-17 and IH-18.
In limited jar testing and in pilot
testing, the City of Austin (a softening
plant) has observed no significant
difference in TOC removal with
increasing doses of ferric sulfate beyond
a low dose. Table I1I-9 shows the
impact of increasing ferric sulfate doses
on the turbidity and TOC concentration
for jar tests in the City of Austin. The
results indicate no significant difference
In TOC removal with increasing doses
of ferric coagulants, but did show that
varying the coagulant dose did impact
the turbidity removal as measured by
NTU.
TABLE 111-9 .—IMPACT OF VARYING
FERRIC COAGULANT DOSE ON TOC
REMOVAL, AUSTIN, TEXAS, 4/9/93,
110 mg/L LIME DOSE, JAR TESTS
Pilot testing confirmed the jar test
results by showing that increasing ferric
sulfate doses beyond that required for
turbidity removal proved to have no
advantage in additional TOC removal
(see Figure 111-19).
BILLING CODE 6660-50-P
Ferric sulfate addi-
tion (mg/L)
3
6
9
12
18
Treated
water tur-
bidity, NTU
16
15
12
12
5.5
Treated
water
TOC
(mg/L)
2.45
2.30
2.46
2.23
2.31
-------
59432 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
g
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-------
Federal Register / Vol. 62. No. 212 / Monday, November 3, 1997 / Proposed Rules
59433
Full-scale plant data from St. Louis
County Water Company and Kansas
City, MO Water Services show that
water temperature, turbidity, and raw
water TOG levels have direct impact
upon the efficiency of lime softening
with iron salt coagulants to improve
TOC removal.
Multiple jar tests on various waters
done by Singer et al. (1996) focused on
the relationship between use of lime
and soda ash and TOC removal. Using
only lime and soda ash (no coagulants),
Singer et al. defined the dosages
required to meet TOC removal
percentages in the matrix. He also
defined the dosages required to remove
10 mg/L of magnesium for nine waters
that met the alkalinity levels in the right
hand column of the matrix (i.e., >120
mg/L). Results of these jar tests are
shown in Table 111-10. Impacts of die
proposed rule would be significant to
softening plants if the TOC removal
requirements were required to be met by
all plants because the requisite lime and
soda ash doses were higher than
existing doses in the plants. Singer et al.
(1996) found'the removal of 10 mg/L of
magnesium hardness to have less
impact, although using the magnesium
criteria would make TOC removal levels
variable and less significant than
meeting the removal levels in the
matrix.
BILLING CODE 6560-50-P
-------
59434 Federal Register / Vol. 62, No. 212 / Monday, November 3. 1997 / Proposed Rules
•I
S
i
3 J
2 §
opeka,KS
118
0.0
81 Lime
041 Soda
II
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239 Lime
172 Soda
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s a
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Z Sis'
BILLING CODE 6660-50-C
-------
Federal Register / Vol. 62. No. 212 / Monday, November 3, 1997 / Proposed Rules
59435
b. Shomey and coworkers—data on
use of SUVA, As discussed previously,
SUVA may be a practical method for
determining which PWSs would be
required to perform enhanced
coagulation and enhanced softening.
SUVA has been found to be a good
indicator of humic content and it is the
humic material that is best removed by
coagulation. Shorney et al. (1996) report
raw water SUVA values <3 in the harder
(softened) source waters that have high
levels of both turbidity and hardness.
SUVA is defined as the UV absorbance
measured as (m"1) divided by the DOC
concentration (mg/L). Typically, SUVA
values <3 L/mg-m are representative of
largely non-humic material, whereas
SUVA values in the range of 4-5 L/mg-
m represent mainly humic material
(Edzwald & Van Benschoten, 1990).
Shorney et al. (1996) report that
coagulation and softening decreased
SUVA, as expected, resulting in SUVA
values between 1 and 2 L/mg-m. The
decrease in SUVA, by treatment, also
corresponded to a decrease in the
apparent molecular weight. Austin's
pilot work indicated that for their water,
no additional TOC removal was
observed with increasing lime and
coagulant doses, demonstrating the
difficulty in coagulation (see Figure III-
20). Austin's water typically has a
SUVA of approximately 2, indicating
that most of the TOC in that water is
non-humic and therefore likely to be
difficult to coagulate. Concurrent work
to fine-tune the enhanced coagulation
criteria has yielded extensive
justification for using SUVA values
below 2 to define raw waters that have
hard-to-treat TOC.
BILLING CODE 6S80-50-P
-------
59436
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
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BILLING CODE 6560-50-C
-------
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
59437
c. Malcolm Pirnte, Inc. modeling.
Efforts to model the removal of TOC in
softening systems were included in an
American Water Works Association
(AWWA) study done by Malcolm Pirnie,
Inc. A database was compiled consisting
of all the known and accessible jar test,
pilot, and full-scale data from softening
studies that investigated TOC removal.
The database was used to develop some
predictive equations for TOC removal
for each raw water TOC level (as
identified in Table III-l of this Notice).
Comparison of the predictive equations
to case-by-case analyses of the same
data base showed the equations to be
fairly accurate for the low TOC waters
(median removal levels of 20-25
percent) and medium TOC waters
(median removal levels of 40 percent).
Insufficient data made analysis
unreliable for the high TOC group.
d, ICR mail survey. In order to obtain
additional Information on the current
TOC removals being achieved by
softening plants, a survey was sent to all
the Information Collection Rule (ICR)
softening utilities (49 plants) requesting
that they fill out a single page of
information with yearly average,
maximum and minimum values for
multiple operating parameters for each
softening plant. The survey also asked
for information regarding the use of
coagulants. Most of the plants reported
using a coagulant in addition to lime
(88%) and some used multiple
coagulants. Iron salts were the most
frequently used coagulants, but alum,
polymers, and starch were also used. Of
the 49 plants responding to the survey,
there was sufficient data to perform an
analysis of TOC removal for 41 plants.
The distribution of the number of
responding plants in each TOC category
is shown in Table ffi-11.
TABLE 111-11.—DISTRIBUTION OF RE-
SPONDING PLANTS BY TOC CON-
CENTRATION
TABLE 111-11.—DISTRIBUTION OF RE-
SPONDING PLANTS BY TOC CON-
CENTRATION—Continued
Raw TOC (mg/L)
0-2
Number
of plants
respond-
ing
5
Number
reporting
sufficient
data to
calculate
%TOC
removal
5
Raw TOC (mg/L)
>2-4
>4_8
>8
Number
of plants
respond-
ing
11
20
4
Number
reporting
sufficient
data to
calculate
%TOC
removal
8
17
3
The data were analyzed with two
goals in mind: to find the appropriate
TOC removal levels for the rule matrix
for softening plants and to determine
what would define an appropriate step
2 for softening systems. To address the
first question, the average TOC percent
removals for each TOC group were
plotted on a percentile basis and are
shown in Figure 111-21 (Clark et al.,
1997) for the 2-4 mg/L TOC, and Figure
111-22 for the 4-8 mg/L TOC (Clark et
al., 1997).
BILLING CODE 6SSO-SO-P
-------
59438
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
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-------
59440
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
To examine the percentage of plants
that would meet the proposed
requirements, the survey data were
analyzed and the results are shown in
Table HI-12. The results in Table 111-12
indicate that the relative impact of
meeting the TOC removal requirement
in the proposed rule would be greatest
in the low TOC group (>2-4 mg/L).
TABLE 111-12.—PERCENTAGE OF SOFT-
ENING PLANTS MEETING CURRENT
PROPOSED REQUIREMENTS
Raw TOC (mg/L)
>2-4 . ..
>4-8
>8
Proposed
1994 re-
quired
percent
removals
20
25
30
Percent-
age of
plants
that met
require-
ments
60
80
66
To address the second question
regarding Step 2 criteria, the survey
results for percent removal TOC and
lime dose were plotted to examine the
relationship between them (see Figure
111-23) and to determine whether a point
of diminishing returns can be identified
for lime addition. Figure 111-23 indicates
that no correlation can be discerned, the
data are highly variable, and no point of
diminishing returns corresponding to a
specific lime dose addition can be
identified. The wide variation in water
quality (e.g., pH, alkalinity, type of
TOC), as well as the differences in
coagulant usage, probably contributed to
data variability.
BILLING CODE 6560-50-P
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Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules 59441
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-------
59442
Federal Register / Vol. 62, No. 212 /Monday, November 3. 1997 / Proposed Rules
Another important issue for softening
systems is the pH level used in the
softening process. As the lime dose is
increased, the pH of the softening
process increases and the character of
the precipitate changes; as the pH rises
above 10, the major precipitate formed
changes from calcium carbonate to
magnesium hydroxide. The TOC
percent removal in the survey data was
plotted versus the pH of softening and
is shown in Figure 111-24 . The data
show that at higher softening pH levels,
generally greater percentages of TOC are
removed. Also as the lime dose is
increased alkalinity is consumed and if
the lime dose is high enough to deplete
the raw water alkalinity, soda ash must
be added to maintain the precipitation
process. Crossing either one of these
thresholds (either changing the
dominant precipitate from calcium
carbonate to magnesium hydroxide or
changing from a lime softening system
to a lime/soda softening system)
constitutes a major change in die
treatment process. Magnesium
hydroxide floe do not act the same as
calcium carbonate floe either in settling
or in sludge treatment and the plant
design for the two precipitates would'be
significandy different. Forcing a plant to
increase pH to the point of having to
add soda ash would also be a significant
treatment change due to pH adjustment
problems, and because the precipitate
would likely be changing at die same
time. Most softening plants are normally
operated without soda ash addition
because of the high cost of soda ash, the
additional sludge production, the
increased chemical addition to stabilize
the water and the increased sodium
levels in the finished water (Randtke et
al., 1994 and Shorney et al., 1996).
BILLING CODE SSW-S9-P
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Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
59443
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59444
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
Raising the pH by adding lime can
have other impacts such as depleting
alkalinity and potentially causing
corrosion problems. To determine what
finished water alkalinity most softening
plants produce, the survey data was
plotted for finished water alkalinity and
TOC percent removal (see Figure 111-25
(Clark et al., 1997)). With only a few
oudiers and regardless of the percent
TOC removal, most plants produce
finished water with alkalinity between
30 and 60 mg/L as CaCO3.
BILLING CODE 6560-50-P
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Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules 59445
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WUJNO CODE UW-W-C
-------
59446
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
The survey obtained basic
information on disinfection practices in
softening plants. Forty percent of the
plants responding predisinfect.
Softening plants predisinfect for the
same reasons that conventional
coagulation plants do, that is, to comply
with Surface Water Treatment Rule
Disinfection requirements, to oxidize
iron and manganese, to control zebra
mussels and Asiatic clams, and to
control taste and odor problems.
Disinfectants in use in softening plants
are as follows:
• 28% of plants use free chlorine for
both primary and secondary
disinfection.
• 50% of plants use free chlorine/
chloramine.
• 10% of plants use chloramine.
• 7% of plants use chlorine dioxide/
chloramine.
• 5% of plants use ozone/chloramine.
In spite of the fact that some 78% of
softening plants are using free chlorine
for at least a portion of their
disinfection, the reported yearly average
THMs indicate that 90 percent of plants
are currently meeting an 80 ng/L level
for THMs (see Figure 111-26 (Clark et al.,
1997)). All reporting softening plants
have average HAAS levels below 60
Hg/L (see Figure 111-27 (Clark et al.,
1997)). For the majority of softening
plants, minor adjustments to
disinfection practices may bring them
into compliance with the proposed total
THM and HAAS MCLs, as long as
predisinfection credit is allowed.
Without predisinfection credit, these
plants could face the major impact of
having to provide disinfection time after
sedimentation, and for at least one of
the reporting utilities, that could mean
significantly increasing the free chlorine
contact time to get the maximum CT
credit by making up for a shortened
detention time. The end result for that
system will likely be an increase in
finished water total THMs over what are
being produced using predisinfection
credit. However, these site-specific
issues will need to be addressed
individually, as removing the precursors
by enhanced softening will also remove
some of the chlorine demand resulting
in less disinfectant addition to obtain
the necessary residual.
BILLING CODE 650-50-P
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Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules 59447
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59448 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
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Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
59449
C, Summary of Key Enhanced
Coagulation and Enhanced Softening
Observations
Based on the data and analysis
outlined above, the M/DBP Advisory
Committee has recommended the
following revisions to the proposed
enhanced coagulation and softening
requirements to address the outstanding
issues on the use of this technology to
control DBF precursors (see Table III-
13). The top row has been modified
from the proposal by lowering the
values by 5%. Enhanced softening
systems are required to comply with the
column for alkalinity > 120 mg/L as
CaCOs.
TABLE lll-13.—1997 PROPOSED REQUIRED REMOVAL OF TOC BY ENHANCED COAGULATION/ENHANCED SOFTENING FOR
SURFACE-WATER SYSTEMS USING CONVENTIONAL TREATMENT
Source water alkalinity, mg/L as CaCO3
Source water TOC, mg/L
>2.0-4.0
>4,0-8.0
>8.0
0-60a
(percent)
35.0
45.0
50.0
>60-120"
(percent)
25.0
35.0
40.0
>120»b
(percent)
15.0
25.0
30.0
•Not applicable to waters with raw-water SUVA £ 2.0 L/mg-m.
bSystems practicing preclpitative softening must meet the TOC removal requirements in this column.
For waters with TOC >4.0 mg/L (6 of
the 9 boxes in the 3x3 matrix), the
TWG felt that 90 percent of these waters
can meet the 1994 proposed step 1 TOC
removal requirements. For waters with
TOC >2.0-4.0 mg/L, the Committee
recommended that the TOC removal
requirements be 35, 25. and 15 percent
for low-, moderate-, and high-alkalinity
waters, respectively. For low-TOC
waters with raw-water SUVA >2 L/mg-
m, the TWG felt that 90 percent of the
systems treating such waters will be
able to comply with the revised step 1
TOC removal levels.
The Committee recommended that
waters with raw-water SUVA £2.0 L/mg-
m be given an exemption to enhanced
coagulation and enhanced softening.
SUVA is an indicator of the humic
content of a water. Coagulation removes
humic matter, so waters with low-SUVA
values contain primarily nonhumic
matter, which is not amenable to
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 or
softening should be added to those
proposed in § 141.135(a)(l)(i)-(iv).
For systems practicing enhanced
coagulation (in any of the 9 boxes in the
matrix) that can not meet the step 1
removal values, a step 2 protocol needs
to be used to develop alternative TOC
removal requirements. In addition to the
current proposed PODR of the slope
criterion of 0.3 mg/L of TOC removal
per incremental 10-mg/L alum dose, the
TWG developed another PODR (a
second option for the protocol), which
is a settled-water SUVA £2.0 L/mg-m.
At this point, the residual TOC is
mainly composed of nonhumic matter
that is not amenable to enhanced
coagulation; therefore, it is not
productive to add additional coagulant.
Because oxidants can destroy UV, but
not TOC, SUVA must be determined on
water that has not been exposed to
oxidants. Thus, using a settled-water
SUVA £2.0 L/mg-m as a PODR should
be done on jar-tested water (as the slope
criterion is done) unless the full-scale
plant is not using preoxidation/
predisinfection. The TWG believes that
these revised requirements will result in
a limited amount of transactional costs
for the PWSs and their primacy
agencies. The Committee recommended
this option to EPA.
Enhanced softening systems that
cannot meet the removal percentages
specified in the TOC removal matrix
must demonstrate that they have met
alternative performance criteria, e.g.,
depressed the alkalinity to a minimum
level or lowered settled water SUVA £
2.0 L/mg-m. Also, systems that remove
a minimum of 10 mg/L of magnesium
hardness (as CaCOs) from their raw
water are exempt for enhanced softening
requirements. Lime softening plants
would not be required to perform lime-
soda ash softening, and no softening
plant will be required to lower treated
effluent alkalinity below 40 mg/L (as
CaCOs), as part of any Step 2 procedure.
Because the determination of SUVA
requires measurement of DOC, the TWG
believed that guidance on this
determination is necessary. DOC is
determined on filtered samples, but it is
important that the filter paper does not
leach DOC. Protocols and quality
assurance measures to ensure that
SUVA is properly measured are
discussed in the analytical methods
section.
Another exception to enhanced
coagulation in the proposed 1994 rule
was for systems that treated water with
<4.0 mg/L TOC and >60 mg/L alkalinity
that achieved TTHMs <0.040 mg/L and
HAAS <0.030 mg/L. Waters with low
TOC and moderate-to-high alkalinity
were expected to be some of the more
difficult to treat with enhanced
coagulation, so this exception
encouraged systems treating such waters
to explore alternative technologies (e.g.,
ozone/chloramines) that could reduce
DBF levels significantly below the
proposed Stage 1 MCLs (i.e., <50
percent of the proposed Stage 1 MCLs).
The analysis of the optimized
coagulation database (Table 111-10 in the
draft NOA) confirms this point. Thus,
the Committee recommended
maintaining this exception to enhanced
coagulation.
D. Request for Public Comment on
Enhanced Coagulation and Enhanced
Softening Issues
The 1994 proposal required that TOC
compliance monitoring be performed
before continuous disinfection. If there
are no limits to where a PWS can add
a disinfectant for compliance with
disinfection requirements, EPA must
address the question of where the TOC
compliance monitoring point should be
located. Two possible compliance
monitoring locations (pre- and post-
filtration) are discussed below. Pre-
filtration sampling may not give utilities
complete TOC removal credit because a
small portion of the TOC may bind with
coagulant but remain in suspension and
fail to settle; it would pass through the
sedimentation basin and be removed by
the filter. Even though the TOC would
be removed by the filter and prevented
from entering the distribution system to
form DBFs, PWSs would not receive
TOC removal credit with a pre-filtration
sampling point. Post-filtration sampling
would ensure utilities receive credit for
all TOC removed by the treatment train.
It is possible, although unlikely, that
some utilities would use filtration to
buttress their TOC removal capability in
place of optimizing the enhanced
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59450 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
coagulation process. EPA solicits
comment on where the TOC compliance
monitoring point should be located.
EPA also requests comment on the
modifications to enhanced coagulation
TOC removal concentrations and other
provisions for enhanced coagulation
outlined above. Finally, EPA requests
comment on the modifications to the
requirements for enhanced softening.
IV. Disinfection Credit
A. 1994 Proposal
The proposed 1994 DBF Stage I rule
discouraged die overuse of disinfectants
prior to precursor (measured as TOC)
removal by not allowing credit for
compliance with disinfection
requirements in the SWTR prior to
removal of a specified percentage of
TOC, at treatment plants using
conventional treatment. The proposed
IESWTR options, scheduled to be
promulgated concurrently with the
Stage 1 DBPR, were intended to include
microbial treatment requirements to
prevent increases in microbial risk. The
purpose of not allowing predisinfection
credit was to maximize removal of TOC
prior to die addition of chlorine or
chloramines, thus minimizing
disinfection byproduct (DBP) formation.
Many drinking water systems use
preoxidation to control a variety of
water quality problems such as iron and
manganese, sulfides, zebra mussels,
Asiatic clams, and taste and odor. The
1994 proposed rule did not preclude the
continuous addition of oxidants to the
influent to the treatment plant to control
these problems. However, the proposed
regulations did not allow credit for
compliance with disinfection
requirements prior to precursor removal
through enhanced coagulation or
enhanced softening. Enhanced
coagulation and enhanced softening
processes would decrease die
concentration of TOC and UV absorbing
compounds, thereby decreasing the
precursor concentration and the
chlorine demand. Thus, analysis
supporting the proposed rule concluded
diat many plants would be able to
comply with die Stage 1 MCLs for
THMs and HAAS of 0.080 mg/L and
0.060 mg/L, respectively, by reductions
in DBP levels as a result of reduced
disinfection practice in the early stages
of treatment. Also, enhanced
coagulation and enhanced softening was
thought to lower the formation of other
unidentified DBFs as well. The 1994
proposal assumed that addition of
disinfectant prior to TOC removal
would initiate DBP formation through
contact of the chlorine with the TOC
thus effectively "mooting" the value of
die EC step. Finally, die analysis
underlying die 1994 proposed
elimination of die preoxidation credit
assumed that the addition of
disinfectant was essentially "mutually
exclusive" of die goal to reduce DBP
formation by die removal of TOC. As
discussed below, new data developed
since 1994 suggests this may not be die
case.
In die 1994 proposal, preoxidation
credit was allowed for some systems
that met any of die following criteria:
—Credit may be taken prior to precursor
removal when die water temperature
was less than 5 °C and die total THM
(TTHM) and HAAS quarterly averages
are no greater than 0.040 mg/L and
0.030 mg/L, respectively.
—PWSs which purchase water from
another entity were allowed to
include diis credit if the TTHM and
HAAS quarterly averages are no
greater dian 0.040 mg/L and 0.030
mg/L, respectively. If diese DBP
averages are higher, then die systems
may use a "C" of 0.2 mg/L or die
measured value (whichever is lower)
and die actual contact time. The
credit is allowed from the disinfectant
feed point, dirough a closed conduit,
and ending at die delivery point in
die treatment plant.
—For ozone, disinfection credit would
be allowed prior to enhanced
coagulation, if ozonation is followed
by biologically active filtration (BAF),
to ensure die control of the ozonation
byproducts by BAF.
—For chlorine dioxide, disinfection
credit would be allowed if the PWS
could demonstrate 95 percent
efficient yield of chlorine dioxide
from sodium chlorite (i.e., die
chlorine dioxide feed stream must
contain less than five percent per
weight free chlorine residual).
EPA solicited comments on several
issues related to die predisinfection
credit requirements:
—Whether preoxidation was necessary
in water treatment to control die
various water quality problems such
as iron and manganese oxidation,
control of taste and odor, zebra
mussels and Asiatic clams?
—Would die addition of a preoxidant
before precursor removal by enhanced
coagulation or enhanced softening
produce excessive DBP levels?
B. New Information Since 1994 Proposal
At the time of the proposed rule, EPA
intended to use data from the ICR to
develop die IESWTR (specifically risk-
based disinfection requirements). For
the reasons outlined in section I.E., die
ICR monitoring data will not be
available for consideration as part of
developing die IESWTR. In light of this,
M/DBP FACA members agreed dial the
IESWTR should include requirements
for a disinfection benchmark to assure
no significant reductions in existing
levels of microbial inactivation while
PWSs complied widi die Stage 1 DBP
requirements, unless they met certain
site-specific conditions. In a separate
NODA concerning die IESWTR
published today, EPA describes die
disinfection benchmark requirements
that it intends to promulgate by
November 1998. The Advisory
Committee was specifically concerned
about maintaining the same level of
disinfection while (1) not compelling
many more systems to install either
substantial replacement contact time or
an alternative disinfectant after
precursor removal than were predicted
in 1994 and (2) still allowing systems to
meet the TTHM and HAAS MCLs. This
was an issue because MCL compliance
predictions in die 1994 proposal were
based on assumptions diat (1) TTHM
and HAAS formation would be limited
by precursor removal, which would
limit die number of systems having to
install alternative disinfectants or
advanced precursor removal (GAC or
membranes) and (2) systems would,
where possible, receive necessary
inactivation credit through addition of
contactors located after precursor
removal processes. Several committee
members were concerned that these
assumptions would result in systems
installing costly technologies or contact
basins in order to meet DBP MCLs that
would prove unnecessary when EPA
was able to develop a risk-based
ESWTR. However, if systems could
continue to receive inactivation credit
for all disinfection used and still meet
DBP MCLs, these costly alternatives to
achieve compliance could be avoided.
The following is information considered
by committee members diat led to the
recommendation to allow disinfection
credit for disinfection used, as is
currendy allowed.
1. ICR Mail Survey—Predisinfection
Practices
To obtain information on die current
predisinfection practices of systems, a
survey was sent out to utilities
participating in die ICR. The results of
die survey of 329 surface water
treatment plants indicated that 80
percent (263) of these plants use
predisinfection for one or more reasons.
A detailed breakdown of die reasons
cited is shown below:
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Federal Register / Vol. 62. No. 212 / Monday, November 3, 1997 / Proposed Rules
59451
Predisinfection reason
Taste and Odor Control
TurbkJity Control
Algae Growth Control ...
Inorganic Oxidation
Microbial Inactlvatlon ....
Other
Number of
"yes" re-
sponses
(% of total)
114(35%)
38 (12%)
177 (54%)
104 (32%)
222 (67%)
27 (8%)
The survey indicated that the majority
of the plants using predisinfection were
doing so for multiple reasons. The main
reported reason for predisinfection was
microblal inactivation, followed by
algae control, taste and odor and
inorganic oxidation. Seventy-seven
percent of plants that predisinfected
reported that their current levels of
Glardia lamblia inactivation would be
lowered if predisinfection was
discontinued and no subsequent
additional disinfection was added to
compensate for change in practice.
Eighty-one percent of plants that
predisinfected would have to make
major capital investments to make up
for the lost logs of Giardia lamblia
inactivation. Thus, to maintain die same
level of microbial protection currendy
afforded, additional contact time would
have to be provided if predisinfection
was eliminated. Most of the surveyed
plants also used preoxidation to control
for taste and odor, algae growth or
inorganic oxidation. Therefore, many
PWSs would have had to continue use
of a predlsinfectant for these problems
and also provide additional contact time
for disinfection credit.
The survey also demonstrated that
many utilities were unfamiliar with the
concept of log inactivation of Giardia
lamblia and did not know how to
determine it. since the SWTR only
requires unfiltered systems to make this
calculation. Instead, many utilities
reported the ratio of CT values, which
is the ratio of the actual CT to the
required value, instead of actual log
inactivation.
In addition to the ICR mail survey,
results from EPA's Comprehensive
Performance Evaluations (CPE) of a total
of 307 PWSs (4 to 750 mgd) reported
that 71 percent of the total number of
plants used predisinfection and 93
percent of those that predisinfected
used two or three disinfectant
application points during treatment.
Based on the above information, EPA
believes that predisinfection is used by
a majority of PWSs for microbial
inactivation, as well as other drinking
water treatment objectives.
2. Summers et al.—Impact of
Chlorination Point on DBF Production
In developing the 1994 proposal, EPA
assumed that the removal of precursors
by enhanced coagulation or enhanced
softening had to precede CU/chloramine
addition in order to lead to reduction of
DBFs. Four investigators tested the
validity of this assumption. Summers
(Summers et al., 1997) summarized the
findings of the four investigators
concerning the impact of moving the
point of chlorination during
coagulation, flocculation and
sedimentation on DBF formation for a
representative range of waters and
treatment conditions. In addition,
studies were carried out at the
University of Cincinnati under the
sponsorship of EPA, the American
Water Works Association (Water Utility
Council-Water Industry Technical
Action Fund) and the Chlorine
Chemistry Council (Solarik et al., 1997).
The results of these studies are
summarized here.
Sixteen source waters have been
evaluated to date. The waters were
selected to proportionately represent the
national source water distribution in the
enhanced coagulation 3x3 (TOC—
alkalinity) matrix as estimated from
AWWA water industry database
(WIDE). Waters were chosen to
represent the >2.0-4.0 mg/L and >4.0-
8.0 mg/L TOC ranges. For TOC >8.0 mg/
L, prechlorination would generally not
be a suitable option, as experience and
computer modeling have shown that
prechlorination of these waters under
the conditions of this study is likely to
yield TTHM and HAAS values that
exceed die 0.080 mg/L and 0.060 mg/L
proposed MCLs, respectively. WIDE
TOC data indicate that less than 10
percent of the surface waters have TOC
concentrations greater than 8.0 mg/L.
The study was conducted using a
bench-scale batch jar testing procedure
with chlorine added at different times to
simulate full-scale continuous flow
conditions with chlorine added at
different points. Alum
(A12(SO4)3»18H2O) was used as the
coagulant for all waters and two alum
doses were examined for 14 of the 16
waters evaluated. The baseline dose was
set at the level required for turbidity
control, while'a second increased dose
was set at the level necessary to meet
die required percent TOC removal in die
3X3 enhanced coagulation matrix. In
three cases, the required TOC removal
was achieved by baseline coagulation.
The jar tests were carried out at ambient
laboratory temperature, (22°C).
Chlorine was added to four parallel
jars at four different times during the
coagulation, flocculation and
sedimentation process for both the
baseline coagulant dose and the
increased coagulant dose: 1) 3 minutes
before rapid mixing (Pre-RM), (2) at the
end of rapid mixing (Post-RM), (3) in the
middle of flocculation (Mid-Floe), and
(4) at the end of sedimentation (Post-
Sed). Additionally, the raw
uncoagulated water was adjusted to the
settled water pH and chlorinated. The
DBF results from the raw uncoagulated
water served as a basis for comparison.
The chlorine doses were chosen to yield
a free chlorine residual of 0.6 ± 0.4 mg/
L after 3 hours of total contact time at
ambient pH (6.1-8.1) and laboratory
temperature (22°C). The 3 hour reaction
time is representative of that of a typical
coagulation, flocculation and
sedimentation process train. At the end
of the 3 hour incubation time, the
reaction was quenched and DBFs were
assessed. Settled water was also
chlorinated under uniform formation
conditions (UFC) (Summers et al., 1996)
to represent distribution system DBF
formation. A more detailed
experimental approach is presented
elsewhere (Solarik etal., 1997, Summers
etal., 1997).
Impact of Point of Chlorination
The impact of moving the point of
chlorination downstream for both
baseline and increased dose coagulation
is shown in Figures IV. 1, IV.2, and IV.3
for TOX, TTHM, and HAAS
concentrations, respectively. The
distribution of data is shown as box and
whisker plots indicating the mean and
median, the 10th, 25th, 75th, and 90th
percentiles, and any data that lies
outside the 10th and 90th percentiles.
Moving the point of chlorination further
downstream decreased the
concentration of DBFs formed after
three hours of contact time with free
chlorine. The DBF concentrations
shown in these three figures are not
intended to represent occurrence levels
of DBFs in the distribution system, only
those which were formed under the
conditions of this study. Figures IV.4,
IV. 5, and IV. 6 show the percent
decrease in DBF formation relative to
that formed in the raw uncoagulated
water.
BILLING CODE 6560-50-P
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59452 Federal Register / Vol. 62. No. 212 / Monday, November 3, 1997 / Proposed Rules
Figure IV. 1: Impact of point of chlorination on TOX formation
500 -
^- 400 -
o
D) tnt\
sf ouu -
g
*"" 200 -
100 -
0-
percentiles
90th-— -?-
8
10ih-*--J-
P I
0
±
Q
— mean
O (
-T- '
I
L-T— ' _
JL
§ i
TOX
n=21
D T=22°C-
o
o
L- 1 T ' '
JL
} o
o
Raw Pre-RM Post-RM Mid-Floe Post-Sed
Summers, R., Solarik, G., Hatcher, V., Isabel, R. and J. Stile. 1997. Reprinted fiom
Proceedings of the 1997 Water Quality Technology Conference, by permission. Copyright
©1997, American Water Works Association.
-------
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
59453
Figure IV.2: Impact of point of chlorination on TTHM formation
,£UU -
180 -
160 -
140 -
=! 120 -
S
;r 100 -
X on
[— 80 -
t-
fiO
40 -
20 -
n -
•mean TTHM
n=30
0 T=22°C
o
n
o
f 8 0 o •
-l- o °
-
1
A , •
88^4--
Raw
Pre-RM Post-RM Mid-Floe. Post-Sed
Summers, R., Solarik, G., Hatcher, V., Isabel, R. and J. Stile. 1997. Reprinted from
Proceedings of the 1997 Water Quality Technology Conference, by permission. Copyright
,©1997, American Water Works Association.
-------
59454 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
Figure IV.3: Impact of point of chlorination on HAAS formation
180 -
160 -
140 -
5" 120 -
< 80 -
60 -
40 -
20 -
0 -
mean HAAS
n=21
0 T=22°C '
0
T o
T :
0 °
, , T T
.. :. "i.™
, L._
o
-J-
•—T— ' I_J
i!r 4- -^ ^C~^
8 o g -dr
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-
•
u -j , , , ...( !
Raw Pre-RM Post-RM Mid-Floe Post-Sed
Summers, R., Solarik, G., Hatcher, V., Isabel, R. and J. Stile. 1997. Reprinted from
Proceedings of the 1997 Water Quality Technology Conference, by permission. Copyright
©1997, American Water Works Association.
-------
Federal Register / Vol. 62, No. 212 / Monday, November 3. 1997 / Proposed Rules 59455
Figure IV.4: Impact of point of chlorination on percent decrease in TOX formation for all waters
(compared to raw)
IUU -
90 -
-, 80 -
^
i" 70 "
| 60 -
l£ 50-
'm 40 -
tn
(B
£ 30 -
& 20 -
10 -
mean TOX
n=21
T=22°C J
8
8 T :
1 1 ri, ^
I
1 4- "
VI::
_L -A- o
8 o
1 1 1 1 I 1
Pre-RM Post-RM Mid-Floe Post-Sed
Summers, R., Solarik, G., Hatcher, V., Isabel, R. and J. Stile. 1997. Reprinted from
Proceedings of the 1997 Water Quality Technology Conference, by permission. Copyright
©1997, American Water Works Association.
-------
59456 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
Figure IV.5: Impact of point of chlorination on percent decrease in TTBM formation for all waters
(compared to raw)
90 -
-? 80 "
^ 70 -
.2
E 60 -
£ 50-
c
-------
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
59457
Figure IV.6: Impact of point of chlqrination on percent decrease in HAAS formation for all waters
(compared to raw)
80 -
•»p
c?»
— ' fin
g 60-
•s
£= 40 -
c
o
u.
•- 20 -
(D
w
ro
-SJ
a
-20 -
-40 -
mfvin HAAR
_e_ n=21
0 T=22°C"
_o_
f
T
0"
0
G o :
Pre-RM Post-RM Mid-Floe Post-Sed
Summers, R., Solarik, G., Hatcher, V., Isabel, R. and J. Stile. 1997. Reprinted from
Proceedings of the 1997 Water Quality Technology Conference, by permission. Copyright
©1997, American Water Works Association.
-------
59458 Federal Register / Vol. 62, No. 212 / Monday, November 3. 1997 / Proposed Rules
Figure IV.7: Impact of point of chlorination and percent TOC removal on percent decrease in TOX
formation for all waters (compared to raw)
£
Q.
CD
Q
I
o
&
100 -,
90 -
80 -
70 -
60 -
50 -
40 -
30 -
20 -
10 -
0
A Pre-RM
a Post-RM
• Mid-Floe
T Post-Sed
— Equivalent removal
TT
TOX
11 waters
n=84
T=22°C
10
20 30
TOC Removal (%)
50
Summers, R., Solarik, G., Hatcher, V., Isabel, R. and J. Stile. 1997. Reprinted from
Proceedings of the 1997 Water Quality Technology Conference, by permission. Copyright
©1997, American Water Works Association.
-------
Federal Register / Vol. 62, No. 212 / Monday. November 3. 1997 / Proposed Rules 59459
Figure IV.8: Impact of point of chlorination and percent TOC removal on percent decrease in TTHM
formation for all waters (compared to raw)
CD
£
n.
CO
Q
-------
59460 Federal Register / Vol. 62. No. 212 / Monday, November 3. 1997 / Proposed Rules
Figure IV.9: Impact of point of chlorination and percent TOC removal on percent reduction in HAAS
formation for all waters (compared to raw)
ation
DBP Fi
se
100
90 -
80 -
70 -
60 -
50 -
40 -
30 -
20 -
10 -
0
A Pre-RM
a Post-RM
• Mid-Floe
r Po'st-Sed
Equivalent removalr
Heaters
™
« . r
10
20 30
TOC Removal (%)
40
50
Summers, R., Solarik, G., Hatcher, V., Isabel, R, and J. Stile. 1997. Reprinted from
Proceedings of the 1997 Water Quality Technology Conference, by permission. Copyright
©1997, .American Water Works Association.
BILLING CODE 6560-5O-C
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Federal Register / Vol. 62. No. 212 / Monday, November 3, 1997 / Proposed Rules 59461
The decrease in DBP formation was
calculated by subtracting the DBP
concentration formed upon chlorination
at a given point in the jar test from that
formed upon chlorination of the raw
waters. Chlorinating 3 minutes prior to
rapid mixing (Pre-RM) led to a median
32,26 and 17 percent decrease in TOX,
TTHM, and HAAS concentrations,
respectively, relative to those formed
upon chlorination of the raw
uncoagulated water. Prechlorinating
more than 3 minutes prior to rapid
mixing was shown to increase the DBP
formation relative to Pre-RM.
For TOX, TTHM. and HAAS, moving
the point of chlorination downstream in
the coagulation, fiocculation, and
sedimentation process decreased DBP
formation and the chlorine demand by
providing additional time for NOM
removal before chlorine could react
with the NOM to form DBFs. While
having only a small impact on average
for TOX, TTHM, and HAAS formation.
moving the point of chlorination from
Pre-RM to Post-RM was very beneficial
for some waters. As expected, the largest
benefit for all parameters investigated
was observed by moving the point of
chlorination to after sedimentation,
which resulted in the lowest DBP
formation. On average, the benefit of
moving the point of chlorination
downstream was greater for HAAS than
for TOX and TTHM.
The median. 10th and 90th percentile
(shown in brackets) decrease in TOX
formation as a result of moving the
point of chlorination from Pre-RM to (1)
post-RM was — 5.4 percent (—17 and 16
percent); (2) mid-Floe was 6.1 percent
(-6.8 and 19 percent); and (3) post-Sed
was 17 percent (4.5 and 34 percent).
The median, 10th and 90tii percentile
(shown in brackets) decrease in TTHM
formation as a result of moving the
point of chlorination from Pre-RM to (1)
post-RM was 1.9 percent (-5.9 and 18
percent); (2) mid-Floe was 13 percent
(0.4 and 28 percent); and (3) post-Sed
was 25 percent (6.5 and 43 percent).
The median, 10th and 90th percentile
(shown in brackets) decrease in HAAS
formation as a result of moving the
point of chlorination from Pre-RM to (1)
post-RM was 5.3 percent (—11 and 23
percent); (2) mid-Floe was 19 percent
(-5.7 and 53 percent); and (3) post-Sed
was 40 percent (26 and 67 percent).
The impact of percent TOC removal
and point of chlorination on TOX,
TTHM, and HAAS formation are shown
in Figures IV.7, IV.8, and IV.9,
respectively. Increased TOC removal
resulted in decreased DBP formation. In
general, moving the point of
chlorination from raw water to Mid-Floe
and Post-Sed resulted in a percent
decrease in DBP formation that was
equivalent to or greater than the percent
TOC removal achieved. Thus, in tills
study, precursor removal was a more
effective DBP control strategy when
used in conjunction with delaying the
point of chlorination until Mid-Floe or
later.
Impact of Alum Dose
Coagulation conditions of the waters
at baseline conditions were determined
based on turbidity control. The median
alum dose used for baseline coagulation
conditions was 30 mg/L (10th and 90th
percentile were 15 and 48 mg/L,
respectively). Under these conditions,
the median TOC removal was 24
percent (10th and 90th percentiles were
6.5 and 38 percent, respectively). For
this study, the alum dose was increased
from the baseline case by a median
value of 22 mg/L (the 10th and 90th
percentiles were 15 and 35 mg/L,
respectively). Increasing the alum dose
resulted in a median increase in TOC
removal to 33 percent (10th and 90th
percentile were 18 and 48 percent,
respectively). Thus, at the higher alum
doses, DBP formation was decreased.
For nine of the waters studied,
increasing the alum dose from baseline
coagulation conditions resulted in TOC
removal equivalent to or greater than
those required by the 3x3 enhanced
coagulation matrix. This yielded a
median increase in the percent TOC
removal of 14 percent. Table I V.I
summarizes the median benefit
associated with moving the point of
chlorination downstream under baseline
coagulation and with increasing the
alum dose to achieve enhanced
coagulation on DBP formation. DBP
formation resulting from chlorine
addition at Pre-RM under baseline
coagulation conditions was used as a
point of reference. The data in the table
indicates that even when
prechlorination is practiced, TOX,
TTHM, and HAAS formation can be
reduced by moving from conventional
to enhanced coagulation. For TOX and
TTHM, the benefits of moving to
enhanced coagulation are greatest when
Post-Sed chlorination is used.
Furthermore, the benefits are greater for
the control of HAAS formation than for
the control of TOX and TTHM
formation.
TABLE IV.1.—IMPACT OF POINT OF CHLORINATION AND ENHANCED COAGULATION ON DBP FORMATION USING PRE-RM
DBP FORMATION UNDER BASELINE COAGULATION CONDITIONS AS BASIS FOR COMPARISON
Pro.RM
Post-RM
Mid-Floe
Post-Sed
Median benefit (%)
TOX (n=7)
Baseline
coagulation
0.3
3.9
11
Enhanced
coagulation
11
10
23
40
TTHM (n=9)
Baseline
coagulation
1.6
8.7
21
Enhanced
coagulation
17
21
36
48
HAAS (n=6)
Baseline
coagulation
5.3
14
35
Enhanced
coagulation
4.7
21
36
61
3-Hour DBP Formation Relative to
Distribution System DBP Formation
Chlorination with a 3-hour holding
time before quenching the reaction
resulted in a significant formation of
DBPs. The 3-hour period was chosen as
it is typical of reaction times in
conventional treatment plants. To get a
general sense of short-term DBP
formation kinetics, DBP formation for
chlorinated settled water held for 3
hours was compared to DBP formation
of settled water chlorinated under UFC
(24 hour holding time). The data
indicate that 3-hour chlorination
resulted in a high percentage of DBP
formation that would normally be
measured in the distribution system.
The median DBP concentrations formed
in 3 hours were 61, 44, and 46 percent
of distribution system formation for
TOX, TTHM, and HAAS, respectively.
This can be thought of as in-plant DBP
formation relative to distribution system
formation for systems with 3-hour post
sedimentation contact.
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59462 Federal Register / Vol. 62, No. 212 / Monday. November 3. 1997 / Proposed Rules
Summary
The results of this study indicate that
enhancing the coagulation process,
while maintaining prechlorination, can
result in decreased DBF formation
(especially for TOX and TTHM) with
greater benefits being realized by
moving the point of chlorination to post
rapid mixing or further downstream for
HAAS and to mid flocculation or post
sedimentation for TOX and TTHM.
Compared to prechlorinating three
minutes before rapid mixing, the
greatest DBF reduction was realized by
moving the point of chlorination to
post-sedimentation, with a median
decrease of 17, 25, and 40 percent in
TOX, TTHM, and HAAS formation,
respectively. However, operational and
regulatory constraints may limit the
extent to which the point of
chlorination can be moved downstream
in the process train, since one
requirement in the IESWTR may be a
disinfection benchmark; which would
require some plants making significant
changes in disinfection practice
(including moving the point of
disinfection) to design the change to
maintain their level of Giardia
inactivation at or above a site-specific
level. This may limit the degree to
which some plants can delay the point
of chlorination without seeking State
approval and potentially modifying
their treatment train to make up lost
Giardia inactivation later in the plant.
C. Summary of Key Observations
TWG analyses indicated that most
PWSs, using enhanced coagulation or
enhanced softening as required, would
be able to meet MCLs of 0.080 mg/L and
0.060 mg/L for TTHM and HAAS,
respectively, while maintaining existing
disinfection practice. This analysis also
indicated that significant precursor
removal and DBF reduction can still be
achieved with predisinfection left in
place. Although in most cases the
reduction in DBF formation is not as
great as would be accomplished in
moving the point of disinfection to after
enhanced coagulation, the Advisory
Committee recommended balancing the
need to maximize precursor removal
against the need to substantially
maintain existing levels of microbial
protection that is provided by many
plants through predisinfection.
However, as noted above, another key
implication of Summers' work is that
some PWSs that only add disinfectant
just prior to coagulant addition (e.g.,
rapid mix), could achieve significant
additional DBF reduction without
sacrificing meaningful disinfection
credit by moving the point of
disinfectant addition from just before to
just after the point of coagulant
addition.
The Advisory Committee
recommended that PWSs continue to
receive credit for compliance with
applicable disinfection requirements for
disinfectants applied at any point prior
to the first customer consistent with the
existing provisions of the 1989 Surface
Water Treatment Rule.
EPA will develop guidance on the
uses and costs of oxidants that control
water quality problems (e.g., Asiatic
clams, zebra mussels, iron, manganese,
algae, taste and odor) and whose use
will reduce or eliminate the formation
of DBFs of public health concern.
D. Request for Public Comments
EPA requests comment on continued
disinfection credit for all disinfectant
use prior to the first customer.
V. Analytical Methods
EPA is requesting comment on the
addition, and in one case the deletion,
of analytical methods for the
disinfectants and DBFs listed below.
These potential changes are based on
information received during the public
comment period or on new information
that has become available since the July
1994 proposed rule.
A. Chlorine Dioxide
The proposed DBF rule included the
same three methods for analyzing
chlorine dioxide (C1O2) that are
approved under the SWTR and ICR
regulations. Two of these methods,
Standard Methods 4500.C1O2 C (APHA
1992) and 4SOO.C1O2 E (APHA 1992),
are amperometric methods. The third
method proposed was Standard Method
4SOO.C1O2 D (APHA 1992), a
colorimetric method using the color
indicator N,N-diethyl-p-
phenylenediamine (DPD).
EPA received several comments
stating that these methods to calculate
ClOa concentration are intrinsically
inaccurate because free chlorine,
chloramines and chlorite are subtracted
from the measurement, causing a
propagation of errors. However, they
stated that the DPD method is
sufficiently accurate for monitoring
C1O2 residuals in drinking water and is
relatively easy to perform.
Method 4SOO.C1O2 C was cited as an
outdated, inaccurate and time
consuming method, subject to
interferences from oxidants commonly
found in drinking water (Dietrich,
1992). Significant, positive interferences
have been described by Gates (1988),
and attributed to mono-and
dichloramines by Haller and Listek
(1948). Method 4500.C1O2 E is a better
method because it utilizes differences in
the physical properties of C1O2, as
opposed to chemical detection of
anionic oxychlorocompounds (Aieta et
al., 1984). Therefore, EPA requests
comments on omitting Method
4500.C1O2 C from the list of approved
methods for the analysis of chlorine
dioxide for compliance with the MRDL
for chlorine dioxide. Comments on
omitting it from 40 CFR 141.74 (SWTR
analytical methods) are also requested.
B. Haloacetic Acids
In 1994, EPA proposed two methods
for the analysis of five haloacetic
acids—Method 552.1 (USEPA, 1992b)
and Standard Method 6233B (APHA
1992). Both methods use capillary
column gas chromatographs equipped
with electron capture detectors. The two
methods differ in the sample
preparation steps. Method 552.1 uses
solid phase extraction disks followed by
an acidic methanol derivitization.
Method 6233B is a small volume liquid-
liquid (micro) extraction with methyl-t-
butyl ether, followed by a diazomethane
derivitization. Standard Method 6233B
was revised (and renumbered 625 IB
(APHA 1995)) to include
bromochloroacetic acid, for which a
standard was not commercially
available in 1994. Recognizing these
improvements, EPA approved Method
6251B for analysis under the 1996
Information Collection Rule (40 CFR
Part 141 or USEPA, 1996b). Several
commenters requested that the revised
and renumbered method, Method
625 IB, also be approved for the analysis
of haloacetic acids under the Stage 1
DBF regulations.
In 1995 EPA published a third
method for HAAs, Method 552.2 (EPA
1995), and subsequently approved it for
HAA analysis under the 1996
Information Collection Rule (40 CFR
Part 141 or USEPA, 1996b). Method
552.2 is an improved method,
combining the micro extraction
procedure of Standard Method 6233B
with the acidic methanol derivitization
procedure of Method 552.1. It is capable
of analyzing nine HAAs. EPA received
comments requesting approval of
Method 552.2 for HAAS analyses
required under this section.
EPA requests comment on the
technical adequacy of using Methods
552.2 and 6251B (formerly 6233B) for
analyzing haloacetic acids. Method
552.1 would continue to be approved
for the analysis of haloacetic acids.
C. Total Trihalomethanes (TTHMs)
Three methods are approved for the
analysis of total trihalomethanes
-------
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
59463
fJTHMs) under 40 CFR 141.24(e). These
same methods were proposed under the
1994 Stage I DBF proposal. One of the
three methods, EPA Method 551, was
revised to Mediod 551.1. rev. 1.0 (EPA
1995). Method 551.1 is approved for ICR
monitoring under 40 CFR 141.142.
Method 551.1 has several
improvements upon Method 551. The
use of sodium sulfate is strongly
recommended over sodium chloride for
the MTBE extraction of DBFs. This
change was in response to a report
indicating elevated recoveries of some
brominated DBFs due bromide
impurities in the sodium chloride (Xie,
1995). EPA's NERL laboratories
confirmed this finding in samples that
were not extracted immediately after the
sodium chloride was added.
Other changes to Method 551.1
include a buffer addition to stabilize
chloral hydrate, elimination of the
preservative ascorbic acid, and
modification of the extraction procedure
to minimize the loss of volatile analytes.
The revised method requires the use of
surrogate and other quality control
standards to improve the precision and
accuracy of the method.
D. Bromate
The proposed rule required systems
that use ozone to monitor for bromate
ion. EPA proposed Method 300.0
(Determination of Inorganic Anions by
IonChromatography)(USEPA, 1993a) for
the analysis of bromate and chlorite
ions. Method 300.0 is used in many
laboratories because it can analyze
bromide, chloride, fluoride, nitrate,
nitrite, orthophosphate, sulfate,
bromate, chlorite and chlorate ions. The
cost of bromate ion analysis was
estimated to range from $50 to $100 per
sample.
At the time of the proposal, EPA was
aware that Method 300.0 was not
sensitive enough to measure bromate
ion concentration at the proposed MCL
of 0.010 mg/L (10 ug/L). EPA recognized
that modifications to the method would
be necessary to increase the method
sensitivity. Studies at Uiat time
indicated that changes to the injection
volume and the eluent chemistry would
decrease the detection limit below the
MCL. There was also an issue
concerning whether bromate formation
could be reliably controlled to levels
below 10 fig/L when ozone is used as
part of the treatment process. Most
commenters agreed that Method 300.0
was not sensitive enough to determine
compliance with a MCL of 10 |ig/L
bromate ion, given that MCLs are set no
less than 5 times the MDLs. One
commenter did achieve a MDL for
bromate ion in the 1-2 p.g /L range
under research laboratory conditions.
Since the proposal, EPA has improved
Method 300.0 and renumbered it as
Method 300.1. EPA intends to approve
this method for use in the final rule; it
is available for review in the Docket.
Method 300.1 specifies a new, high
capacity ion chromatography (1C)
column that is used for the analysis of
all anions listed in method instead of
requiring two different columns as
specified in Method 300.0. The new
column has a higher ion exchange
capacity that improves chromatographic
resolution and minimizes the potential
for chromatographic interferences from
common anions at concentrations
typically 10,000 times greater than
bromate ion. For example,
quantification of 5.0 |ig/L bromate is
feasible in a matrix containing 50 mg/
L chloride. Minimizing the interferences
permits the introduction of a larger
sample volume to yield a method
detection limit of 2 jig/L. Sample
analysis time is approximately 30
minutes per sample.
An 1C column's capacity is directly
proportional to its operating back
pressure at a given flow rate and the
older 1C systems may not be able to
tolerate the higher back pressures
required when using these new 1C
columns. Consequently, in order to
perform this analysis, some laboratories
with 1C systems over 15 years old may
need to upgrade their instrumentation to
current technology. Newer instruments
can easily be operated under these
conditions.
As in Method 300.0, Part A of the
revised method contains procedures for
measuring the common anions of
bromide, nitrate, nitrite, fluoride,
chloride, sulfate and phosphate. Part B
contains procedures for measuring the
disinfection byproduct anions of
bromate, chlorite and chlorate. Bromide
ion is also included in Part B to
determine its potential presence as a
disinfection byproduct precursor.
The anions are split into two distinct
parts due to the disparity in the relative
concentrations expected in drinking
water. Method 300.1 analyzes mg/L
levels of the Part A common anions and
jig/L levels of the Part B inorganic
disinfection byproducts and bromide
ion. To accommodate this, the
recommended sample volume injected
for Part A is 10 jiL and for Part B is 50
|iL, when using a 2 mm diameter
column. The lower injected sample
volume for Part A is required to
compensate for their higher (mg/L)
concentrations. If this injected volume
is not reduced, poor analyte response
characteristics are observed and the
integrity of the data is compromised.
The higher injected sample volume for
Part B is required to yield low detection
limits for the inorganic disinfection
byproducts, specifically bromate.
Analysis for Part A and Part B cannot be
concurrent without sacrificing
analytical integrity and therefore a
separate 30 minute analysis must be
done for each concentration range.
To preserve samples for chlorite,
chlorate, and bromate analyses, the
method requires the addition of
ethylenediamine (EDA) at a final sample
concentration of 50 mg/L. EDA is
primarily used as a preservative for
chlorite. Chlorite is susceptible to
degradation both through catalytic
reactions with dissolved iron salts and
reactivity towards free chlorine which
exists as hypochlorous acid/
hypochlorite ion in most drinking water
as a residual disinfectant. EDA serves a
dual purpose as a preservative for
chlorite by chelating iron as well as any
other catalytically destructive metal
cations and removing hypochlorous
acid/hypochlorite ion by forming an
organochloramine. EDA also preserves
the integrity of bromate concentrations
by binding with hypobromous acid/
hypobromite which is an intermediate
formed as a byproduct of the reaction of
ozone or free chlorine with bromide ion.
If hypobromous acid/hypobromite is not
removed from the matrix, further
reactions may form bromate ion.
Method 300.1 was validated for the
inorganic DBFs and bromide by
conducting nine replicate analyses at
two different fortified levels of seven
water matrices including reagent water,
simulated high ionic strength water,
untreated surface water, untreated
ground water, chlorinated drinking
water, chlorine dioxide treated drinking
water, and ozonated drinking water.
Holding time studies have been
incorporated into these validation
studies with aliquots of each fortified
matrix currently being stored as
unpreserved and EDA preserved at 4°C.
These stored sample matrices will be
monitored out to 30 days to determine
appropriate holding times. MDL
determinations have been completed in
both reagent water and high ionic
strength water. Results of these
validation studies are included in the
method.
With Method 300.1, EPA projects that
more laboratories will achieve lower
detection limits for bromate and report
data having better precision and
accuracy. Compliance monitoring for
low levels of bromate ion will require an
appropriate certification process to
ensure that the measurements are
accurate. Although there may be a
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59464 Federal Register / Vol. 62. No. 212 / Monday, November 3, 1997 / Proposed Rules
limited number of laboratories that will
be qualified to do such analyses, there
should be adequate laboratory capacity
for bromate ion compliance monitoring.
EPA estimates that 250 treatment plants
utilizing ozone will be monitored for
bromate once per month, for a total of
3,000 samples per year.
E. Chlorite
The proposed rule required
monitoring for the chlorite ion for those
systems using chlorine dioxide for
disinfection. The proposed rule
included Method 300.0 (ion
chromatography) for chlorite analysis.
Other methods using amperometric and
potentiometric techniques were
considered, but EPA decided that only
the ion chromatography method (300.0)
would produce results with the
precision needed for compliance
determinations. Several commenters
suggested that EPA permit other
methods for chlorite.
Since the proposed rule, Method
300.1, which uses ion chromatography,
was developed for bromate ion (as
discussed above). Since Method 300.1
can also be used to analyze for chlorite
ion, EPA requests comment on allowing
both Methods 300.0 and 300.1 as
approved methods for the analysis of
chlorite ion.
F. Total Organic Carbon (TOC)
The proposed rule included two
methods for analyzing TOC: Standard
Method 5310 C and 5310 D (APHA
1992). These methods were selected
because they cite a detection limit ^0.5
mg/L and a precision of ± 0.1 mg/L
TOC. Standard Method 5310 B (18th
edition) was considered, but not
proposed because the method had a
detection limit of 1 mg/L. The proposal
stated that if planned improvements to
the instrumentation in 5310 B were
successful, the next version would be
considered for promulgation.
Improvements were made to method
531 OB and were included in a revised
method in the 19th edition of Standard
Methods (APHA 1995). Based on these
improvements, method 5310B (19th
edition) was approved for TOC analyses
under the Information Collection Rule.
Several commenters requested that
Standard Methods 5310B also be
approved for TOC analysis under this
rule because the newer instrumentation
achieves a detection limit of 0.5 mg/L
TOC.
Since the ICR was promulgated,
another revision of 5310 B was
published in the supplement to the
Standard Methods 19th Edition (APHA
1996). EPA intends to approve this
method for the analysis of TOC. EPA
requests comments on the technical
equivalency of Methods 5310 B, C, and
D in the Supplement to Standard
Methods 19th Edition and those same
methods in the 19th Edition.
G. Specific Ultraviolet Absorbance
(SUVA)
Specific Ultraviolet Absorbance at 254
run (SUVA) is an indicator of the humic
content of a water. Waters with low
SUVA values contain primarily non-
humic matter and are not amenable to
enhanced coagulation. As discussed in
section III, systems may demonstrate
that enhanced coagulation or enhanced
softening is unnecessary if the raw
water after being filtered through a 0.45
(im filter has a SUVA below 2 L/mg-m.
SUVA is a calculated parameter
obtained by dividing a sample's
ultraviolet light absorbance at a
wavelength of 254 run (UV254), by the
dissolved organic carbon (DOC), and
multiplying by 100:
SUVA = 100 (cm/m) [ UV254 (cm-i)/DOC
(mg/L)]
Two separate analytical methods are
necessary to make this measurement: 1)
UV254 and 2) DOC.
1. UVz54. EPA approved Standard
Methods 5910 (APHA 1995) for
measuring UVzs4 under the Information
Collection Rule and intends to approve
its use under the disinfection
byproducts rule. EPA requests
comments on this and other methods for
measuring LJV2S4.
2. DOC. Standard Methods (19th
Edition-Supplement) (APHA 1996)
defines DOC as the fraction of TOC that
passes through a 0.45 jom-pore-diameter
filter. DOC is measured by performing
an analysis for TOC on the sample
filtrate. Filtration eliminates particulate
organic matter but may contaminate the
sample if carbon-containing compounds
leach from the filter. Standard Methods
5310 B, 5310 C and 5310 D require that
filters be rinsed before use and checked
for their contribution to DOC by
analyzing a filtered blank. Contact with
organic material such as plastic
containers, rubber tubing, etc. must be
kept to a minimum to prevent
contamination. EPA requests comments
on the approval of Standard Methods
5310 B, 5310 C and 5310 D for
measuring DOC for the SUVA
calculation.
EPA is aware of several issues relating
to the measurement of SUVA that are
not addressed in the methods above. In
determining SUVA, DOC and UV254 are
both to be measured from the same
sample filtrate, which is prepared by
filtering a raw water sample through a
pre-washed 0.45 (im filter paper.
Standard Methods 5910 (UV)
recommends to wash the filter with 50
mL of organic-free water to avoid
contamination, however, more rinsate
may be necessary to eliminate the DOC.
Because disinfectants/oxidants
(chlorine, ozone, chlorine dioxide,
potassium permanganate) can destroy
UV but not DOC, SUVA needs to be
determined on water prior to the
application of disinfectants/oxidants. In
the raw water, this is usually not a
problem. If disinfectants/oxidants are
applied in raw-water transmission lines
upstream of the plant, then raw-water
SUVA should be based on a sample
collected upstream of the point of
disinfectant/oxidant addition.
For determining settled-water SUVA,
if the plant applies disinfectants/
oxidants prior to the settled water
sample tap, then settled-water SUVA
should be determined in jar testing.
Finally, the use of iron-base coagulants
can interfere with UV measurements, as
dissolved iron can penetrate the filter
paper.
To address these issues in more
detail, EPA intends to provide guidance
on SUVA measurements in the
Guidance Manual for Enhanced
Coagulation (USEPA, 1997d). The
manual will include guidance on
sampling, sample preparation, filter
type, pH, interferences to UV, high
turbidity waters, quality control, etc.
EPA requests comment on other issues
that should be addressed in the
guidance, as well as any
recommendations on how the above
issues should be addressed.
H. Summary of Key Observations
Since the 1994 proposal,
improvements have been made to the
analytical methods for trihalomethanes,
haloacetic acids, total organic carbon,
bromate ion and chlorite ion. EPA
received comments to include Method
552.2 and 625 IB for HAAs, and Method
5310B for TOC. Commenters made a
general suggestion to approve methods
promulgated under the ICR rule in the
Stage 1 DBP rule. EPA intends to
approve these methods and if
appropriate, promulgate their most
recent versions. EPA also intends to
approve Method 300.1, the revised
method for bromate ion, and permit its
use for chlorite ion.
I. Request for Public Comments
1. EPA requests additional comments
on omitting Method 4500.C1O2 C from
the list of approved methods for the
analysis of chlorine dioxide.
2. EPA requests additional comments
on the approval of EPA Method 552.2
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59465
and Standard Method 6251B for
analyzing haloacetic acids.
3. EPA requests comment on
replacing Method 300.0 with Method
300.1 for the analysis of bromate ion.
4. EPA requests comment on allowing
both Method 300.0 and 300.1 as
approved methods for the analysis of
chlorite Ion.
5. EPA requests comments on the
technical equivalency of Metiiods 5310
B, C and D in the Supplement to
Standard Methods. 19th edition and
those same methods in the 19tii edition
of Standard Methods for measuring TOG
and DOC.
6. EPA requests comments on the
methods and filtration procedures for
measuring SUVA.
VI. MCLs forTTHM, HAAs, Chlorite
and Bromate
A. 1994 Proposal
The 1994 proposal for Stage 1 of the
DBPR included MCLs for total
trlhalomethanes CTTHMs), the sum of
five haloacetic acids (HAAS), bromate
and chlorite at 0.080,0.060,0.010 and
1.0 mg/L. respectively (EPA, 1994b). In
addition to the proposed MCLs, Subpart
H systems—utilities treating either
surface water or groundwater under the
direct influence of surface water—that
use conventional treatment (i.e.,
coagulation, sedimentation, and
filtration) or precipitative softening
would be required to remove DBF
precursors by enhanced coagulation or
enhanced softening. The removal of
total organic carbon (TOC) would be
used as a performance indicator for DBF
precursor control.
As part of the proposed rule, EPA
estimated that 17% of PWSs would
need to change their treatment process
to alternative disinfectants (ozone or
chlorine dioxide) or advanced precursor
removal (GAC or membranes) in order
to comply with the Stage 1
requirements. This evaluation was
Important to assist in determining
whether the proposed MCLs were
achievable and at what cost. This
evaluation required an understanding of
the baseline occurrence for the DBFs
and TOC being considered in the Stage
1 DBPR, an understanding of the
baseline treatment in-place, and an
estimation of what treatment
technologies systems would use to
comply with the Stage 1 DBPR
requirements.
For systems switching to ozone or
chlorine dioxide, separate MCLs were
proposed for inorganic DBFs associated
with their usage: bromate and chlorite,
respectively. Although the theoretical
10~4 risk level for bromate is 5 ]ig/L. an
MCL of 0.010 mg/L (10 |ig/L) was
proposed (because available analytical
detection methods for bromate were
reliable only to the projected practical
quantification limit (PQL) of 10 ng/L
(USEPA, 1994b). For chlorite, the MCL
goal (MCLG) was 0.08 mg/L, due (in
part) to data gaps that required higher
uncertainty factors in the MCLG
determination. The Chemical
Manufacturer's Association (CMA)
agreed to fund new health effects
research on chlorine dioxide and
chlorite—with EPA approval of the
experimental plan—to resolve these
data gaps.
In the preamble to the proposed rule,
EPA requested comment on several
issues related to the MCLs and
requested any new information that may
influence the MCLs. For bromate, EPA
requested comment on whether there
were ways to set (or achieve) a lower
MCL (i.e., 0.005 mg/L [5 ng/L]) and
whether the PQL for bromate could be
lowered to 5 ng/L in order to allow
compliance determinations for a lower
MCL in Stage 1 of the proposed rule.
For chlorite, EPA requested comment
on the appropriate MCL (i.e., at the
MCLG, at the proposed MCL, or above
the MCLG but below the proposed
MCL), the feasibility of achieving a
particular MCL, and whether there were
other benefits to chlorine dioxide
disinfection that should be considered
when balancing the health risks
associated with chlorite.
B. New Information Since 1994 Proposal
1. TTHM and HAAS MCLs
At the direction of the Advisory
Committee, the Technologies Working
Group (TWG) reviewed MCL
compliance predictions developed for
the 1994 proposal because of concern by
several Committee members that
modifications to the rule would result in
more PWSs not being able to meet the
TTHM and HAA MCLs without
installation of higher cost technologies
such as ozone or GAC. The members
were particularly concerned that
allowing disinfection inactivation credit
prior to precursor removal (by enhanced
coagulation or enhanced softening) in
order to prevent significant reductions
in microbial protection would result in
higher DBF formation and force systems
to install alternative disinfectants, or
advanced precursor removal to meet
TTHM and HAAS MCLs. As discussed
earlier in today's Notice in Section IV.
(Disinfection Credit), PWSs can achieve
significant reduction in DBF formation
through the combination of enhanced
coagulation (or enhanced softening) and
moving the point of disinfection
downstream from coagulant addition,
while preventing significant reduction
in microbial protection. The TWG's
analysis of the cumulative effect of these
changes was that there would be no
significant increase in the percentage of
PWSs that would need to install higher
cost technologies to meet TTHM and
HAAS MCLs and no significant
reduction in microbial protection. The
TWG estimated that 6.4% (based on
WIDE data) to 15% (based on AWWSCo
data) of PWSs would install alternative
disinfectants or advanced precursor
removal technologies based on the new
information presented in this Notice,
which is less.than estimated in the 1994
proposal. It is now estimated that these
other systems will either switch to
chloramines or move the point of
predisinfection, which are low cost
means of compliance. EPA has included
a detailed discussion of the TWG's
prediction of technology choices in
Section VIII of this Notice. EPA
continues to believe the proposed MCLs
are achievable without large-scale
technology shifts. EPA requests
comment on the new information and
related analysis outlined in Section VIII.
2. Bromate
The proposed MCL of 0.010 mg/L for
bromate was based on a projected
practical quantisation level (PQL) that
would be achieved by improved
methods. The PQL of the revised
method is approximately 0.010 mg/L for
bromate, as discussed in Section V
(Analytical Methods). EPA is not aware
of any new information that would
lower the PQL for bromate and thus
allow lowering the MCL. As a result,
EPA concluded that the proposed
bromate MCL is appropriate and
requests comment on this position.
3. Chlorite
The proposed chlorite MCL of 1.0
mg/L was supported by the Regulatory
Negotiation Committee because 1.0
mg/L is the lowest level practicably
achievable by typical systems using
chlorine dioxide, from both treatment
and monitoring perspectives. Since the
proposed MCLG of 0.08 mg/L contained
several uncertainty factors because of
data gaps, i.e., lack of two-generation
reproductive study, CMA funded a 2-
generation reproductive study with
chlorite, witfi EPA approval of the study
design. CMA has submitted this study
for EPA review. EPA has not completed
its review of the study at the time of this
Notice. EPA intends to publish the
results of its review in a future Notice
of Data Availability, along with any
possible modifications to regulatory
requirements that its review may justify.
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EPA has included a more complete
discussion of this issue earlier in this
Notice (Section II. Health Effects) and
the CMA study is available for review in
the Docket. In addition, an EPA
sponsored peer-review of the CMA
study is included in the Docket. EPA is
requesting comments on the
conclusions of this peer review report.
VII. 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 DBFs.
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 padiogens and
DBFs 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 DBFs 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 die necessary protection from
any downside microbial risk that might
odierwise result when systems of this
size attempted to achieve compliance
widi 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 die same time as
the Stage 1 DBPR), were expected to
need some period of monitoring for
DBFs in order to adjust dieir treatment
processes to also meet die 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 die
staggered M-DBP regulatory
development schedule developed by the
Negotiating Committee. Section
1412(b)(2)(C) requires that die standard
setting intervals laid out in EPA's
proposed ICR rule be maintained even
if promulgation of one of die M-DBP
rules was delayed. As noted above, diis
staggered regulatory schedule was
specifically designed as a tool to
minimize risk/risk tradeoff. A central
component of diis approach was die
concept of "simultaneous compliance"
which provides that a PWS must
comply with new microbial and DBF
requirements at die same time to assure
diat in meeting a set of new
requirements in one area, a facility does
not inadvertendy increase die risk (i.e.,
die risk "tradeoff') in die other area.
The SDWA 1996 Amendments also
changed two statutory provisions that
elements of die 1992 Negotiated
Rulemaking Agreement were based
upon. As oudined above, the 1994 Stage
1 DBPR and ICR proposals provided diat
18 months after promulgation large
PWSs would comply widi die rules and
States would adopt and implement die
new requirements. Section 1412 (b) (10)
of the SDWA as amended now provides
dial drinking water rules shall become
effective 36 months after promulgation
(unless die Administrator determines
that an earlier time is practicable or diat
additional time for capital
improvements is necessary—up to two
years). In addition, Section 14l3(a)(l)
now provides diat States have 24
instead of die previous 18 months to
adopt new drinking water standards tiiat
have been promulgated by EPA.
Discussion
In light of the 1996 SDWA
amendments, developing a compliance
deadline strategy diat encompasses both
the Stage 1 DBPR and IESWTR, as well
die related LTESWTR and Stage 2
DBPR, is a complex challenge. On die
one hand, such a strategy needs to
reflect new statutory provisions. On die
other, it needs to continue to embody
key reg-neg principles reflected in bodi
the 1994 ICR and Stage 1 DBPR
proposals; principles diat bodi
Congressional intent and die structure
of die new Amendments, themselves,
indicate must be maintained.
An example of die complexity that
must be addressed is die relationship
between die principles of risk/risk
tradeoff, simultaneous compliance, and
the staggered regulatory schedule
adopted by Congress. Under the 1996
SDWA amendments, die staggered
regulatory deadlines under Section
1412(b)(2)(C) call for die IESWTR and
Stage 1 DBPR to be promulgated in
November 1998 and die LTESWTR in
November of 2000. However, a
complicating factor reflected in the
Negotiated Rulemaking Agreement of
1992 and contained in die 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 die LTESWTR covers
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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).
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 ffiSWTR 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
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.
OPTION 1.—IMPLEMENT 1994 PROPOSAL SCHEDULE
Rule (promulgation)
GWDR (1 1/00)
Surface water PWS
£lOk
5/00
5/00
5/02 (if required)
NA
<10k
5/02
NA
5/02
NA
Ground water PWS
s10k
5/02
NA
NA
(')
<10k
11/03
NA
NA
(')
1 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
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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
Rule (promulgation)
DBP 1 (11/98)
lESWTR (1 1/98)
LTESWTR (11/00) . .
GWDR (1 1/00)
Surface water PWS
510k
11/01
11/01
11/03 (if required)
NA
<10k
11/03
NA
11/03
NA
Ground water PWS
alOk
11/03
NA
NA
(i\
<10k
5/05
NA
NA
m
1 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
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 oudined 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
tiiese 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 montii (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
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59469
requests comment on this issue. As addressing ground water systems that amendments as well as the intent of the
discussed below, EPA believes there is reflects the requirements of the SDWA reg-neg process.
a reasonable compliance strategy for
OPTION 3.—REQUIRE COMPLIANCE WITH ALL RULES WITHIN THREE YEARS OF PROMULGATION
Rule (promulgation)
DBP 1 (11/981
IESWTR (11/98)
LTESWTR (11/00)
GWDR (11/00)
Surface water PWS
£10k
11/01
11/01
11/03 (if required)
NA
<10k
11/01
NA
11/01
NA
Ground water PWS
aiOk
11/01
NA
NA
11/03
<10k
11/01
NA
NA
11/03
Under this approach, all systems
would be required to comply with Stage
1DBPR. 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 oudined 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
Rule (promulgation)
DBP 1 (11/98)
IESWTR (11/98>
I TF^WTR f 11/00)
GWDR (11/00)
Surface water PWS
S10k
11/01
11/01
11/03 (if required)
NA
<10k
11/03
NA
11/03
NA
Ground water PWS
£lOk
11/03
NA
NA
11/03
<10k
11/03
NA
NA
11/03
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
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 tfiat 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 oudined 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
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59470 Federal Register / Vol. 62, No. 212 / Monday, November 3. 1997 / Proposed Rules
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 IDBPR 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 CFR141.
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 DBF
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 141 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.
VIII. Economic Analysis of the M-DBP
Advisory Committee Recommendations
The Regulatory Impact Analysis (RIA)
for the 1994 proposed rule (USEPA,
1994b) was based on information
generated from the Disinfection
Byproducts Regulatory Analysis Model
(DBPRAM) and modified by a
Technologies Working Group (TWG),
which consisted of technical
representatives of members of the
regulatory negotiation committee. The
regulatory impact analysis (RIA), which
provided information on the costs and
benefits of the proposed rule, was
developed using the DBPRAM in
conjunction with the TWG. Since the
proposal, new information has become
available which EPA has used to modify
the estimated costs and benefits. This
new information is discussed below.
EPA requests comments on the
adequacy of the new data, how the new
data have been used, and any additional
data that would improve the assessment
of costs and benefits.
A. Plant-Level DBF Treatment
Effectiveness and Cost
The 1994 RIA analysis was supported
by modeling apparatus known as the
DBPRAM. The DBPRAM, which was
actually a collection of analytical
models, utilized Monte Carlo simulation
techniques to produce national forecasts
of compliance and resulting exposure
reductions for different regulatory
scenarios. For a complete discussion of
the DBPRAM model, see the RIA from
the proposed rule (USEPA, 1994b).
Initially, the TWG revisited the
modeling tools to re-examine the results
with new assumptions regarding the
effectiveness of enhanced coagulation in
the presence of predisinfection. A
central component of the DBPRAM
apparatus is the Water Treatment Plant
model (WTP). Initial investigations by
Malcolm Pirnie, Inc., concluded that the
manner in which predisinfection is
characterized in the WTP model makes
it impossible to distinguish the effects of
the proposed change in the Stage 1
Disinfectants and Disinfection
Byproducts Rule (DBPR). The model
makes simplifying assumptions about
the point of predisinfection and does
not permit marginal analysis of shifting
this point. In the 1994 RIA analysis, the
point of predisinfection did not matter
since the proposal called for elimination
of Enhanced Surface Water Treatment
Rule (ESWTR) credit for predisinfection
and the analyses or models developed
for the RIA assumed predisinfection
would be eliminated.
Based on TWG analysis, the cost and
effectiveness of enhanced coagulation
(as captured in the 3-by-3 matrix) was
made more consistent with the
assumptions made in the DBPRAM for
the 1994 RIA analysis. The TWG
believed that the changes in the
enhanced coagulation matrix should not
therefore affect the decision tree.
The major role of the DBPRAM
modeling apparatus in the 1994 RIA
analysis was to help the TWG verify
assumptions for a compliance decision
tree forecast that is suitable as the basis
for national cost calculations. The
driving factor in the 1994 RIA analysis
became the degree to which water
systems would have to cross over the
threshold from standard treatment
technologies to more expensive
technologies such as GAC, ozone,
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Federal Register / Vol. 62, No. 212 / Monday, November 3. 1997 / Proposed Rules 59471
the 1994 DBPRAM analyses, and also
familiar with the WIDE and AWWSCo.
data sets, performed the re-evaluation of
the compliance decision tree forecast
based upon the Advisory Committee
recommendations. This was performed
by making case-by-case evaluations of
each water system in the data set for
which total trihalomethane (TTHM) or
haloacetic acids (HAAs) exceeded 64
|iug/L or 48 p.g/L, respectively. These
numbers are design targets for
maximum contaminant levels (MCLs) of
80 |Ag/L and 60 |ig/L, reflecting the
variation in DBF levels from year to
year.
Table VIII-1 presents a side-by-side
comparison of compliance forecasts
developed for the 1994 RIA and
analyses of the 1996 WIDE data and the
1991 and 1992 AWWSCo. data.
chlorine dioxide, and membranes.
Keying on this feature, die TWG formed
In 1997 to provide technical support to
the M-DBP Advisory Committee
designed an approach to re-evaluating
the 1994 national cost analysis by re-
evaluating the manner in which newly
available information and changes in
the proposed rules would affect this
advanced technology threshold in the
compliance decision tree forecast.
The TWG evaluated two sets of data
that documented levels of TOC, TTHM,
HAAS, and predisinfection practices for
groups of water systems. The 1996
Water Industry Data Base (WIDE) data
set provided data for 308l water
systems nationwide. The American
Waterworks Service Company
(AWWSCo.) data set provided two years
of data (1991 and 1992) for 52 plants.
located primarily in the Northeast and
Midwest
Using these two data sets and
experience and personal knowledge of
many of these particular plants, the
1997 TWG was able to undertake a
plant-by-plant assessment of the
prospective compliance choices of the
plants likely to have to change treatment
in order to comply with the Advisory
Committee recommendations for the
Stage 1 DBPR. By computing the
percentage of systems forecast to require
the more expensive advanced
treatments, it was possible to see if
results were in the same range as that
projected in the 1994 RIA analysis. This
decision tree analysis is detailed below.
B. Decision Tree Analysis—Compliance
Forecasts
A sub-group of the 1997 TWG
consisting of individuals familiar with
TABLE Vlll-1.—STAGE 1 DBF COMPLIANCE FORECAST
Treatment technology to be implemented
Chlorine Dioxide
1993 stage
1 RIA (per-
cent)
28
3
10
43
5
6
6
0
Analysis of
1996 WIDB
data
39.0
16.6
19.0
19.0
2.2
2.2
0.3
1.6
0.3
Analysis of
AWWSCo
1991-1992
data (per-
cent)
22
28
35
7.5
7.5
The compliance forecast developed
for the 1994 RIA using the DBPRAM
(column 2 of Table VIII-1) predicted
that 17 percent of systems would adopt
advanced treatments (ozone, chlorine
dioxide, GAC, or membranes) in order
to comply with the Stage 1 MCLs. In
many instances, the adoption of
advanced technologies was forecast as a
result of the companion requirements of
the proposed IESWTR to increase
disinfection to assure a 10 ~4 risk level
for Glardia.
Since the 1994 proposal, the IESWTR
requirement to achieve a 10~4 risk level
for Giardla has been replaced with a
"disinfection benchmark" requirement
intended to preserve the status quo of
disinfection practices. As a result, the
TWG predicted fewer systems to adopt
advanced technologies. In addition,
probable compliance choices can be
evaluated based on the existing
treatment configuration and
performance rather than having to first
predict the effects of changes in
disinfection, as was done with the
DBPRAM previously.
The 1997 TWG reviewed the data for
the 73 of 308 2 systems in the 1996
WIDB data set (23.7%) that had either
TTHM S64 ng/1 or HAA(5) S48 ng/1. The
systems were evaluated at a plant-by-
plant level, incorporating multiple plant
compliance strategies where applicable
and other data, such as that available
from the ICR plant schematics. Results
are tabulated in Table VIII-1. Based on
the case-by-case analysis of this sample,
the TWG predicted that 20 of the 73
systems would require advanced
technologies in order to comply with
the proposed MCLs. This equates to a
decision tree percentage of 6.4% (20/
308) based on WIDB data to 15% (based
on AWWSCo data). The TWG assigned
another 51 systems (16.6%) to a
compliance category consisting of
various combinations of relatively low
cost strategies, such as moving the point
of predisinfection and using
chloramines. Only two of the 73 systems
were projected to install enhanced
coagulation purely for purposes of
meeting the MCLs.
The 1997 TWG did not forecast the
number of systems in the WIDB data set
that would have to install enhanced
coagulation in compliance with the
treatment technique requirements in the
Stage 1 proposal. Because several years
have passed since the negotiated
rulemaking process, some water systems
have probably already moved ahead
with implementation of enhanced
coagulation. Indeed, some systems were
achieving enhanced coagulation
standards even before it was given its
name during the negotiated rulemaking
1 Percentages reported here differ from those
computed earlier by members of the TWG due to
a correction In the denominator. Previous
calculations used 399 systems as a denominator,
but since 91 of them did not report TTHM or HAA
data, they were not Included in these computations.
1 Percentages reported here differ from those ,
computed earlier by members of the TWG due to
a correction In the denominator. Previous
calculations used 399 systems a3 a denominator,
but since 91 of them did not report TTHM or HAA
data, they were not included in these computations.
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59472 Federal Register /Vol. 62. No. 212 / Monday, November 3, 1997 / Proposed Rules
process. In order to complete a
compliance forecast (decision tree
analysis) for the final Stage 1 Rule, the
Agency needs to know what proportion
of the universe is already achieving
enhanced coagulation and what
proportion will have to install enhanced
coagulation. The 1996 WIDE data is the
best available source of information
from which to develop these estimates.
The 1996 WIDE provides data on
influent total organic carbon (TOC),
effluent TOC, and alkalinity by plant, as
well as TTHM and HAAS data by
system. Using this information, the 1997
TWG developed an assessment of the
extent to which enhanced coagulation is
already in place. The resulting decision
tree percentages are summarized in
Table VIII-1. These percentages are
used to estimate national cost.
The 1997 TWG performed a parallel
case-by-case analysis using the
AWWSCo. 1991-92 data representing 52
systems; results are in Table VIII-1. The
AWWSCo. and WIDE results are clearly
different, and potentially reflect a
number of factors: (1) more adverse DBF
control conditions in the waters
represented in this data set; (2) greater
use of chloramines as a residual
disinfectant by AWWSCo. plants, and
(3) the influence of having 2 years of
data illustrates how TTHM and HAAS
values threshold exceedances can
change from year to year for a given
system. (These features of the
AWWSCo. data are discussed in Chapter
4 of the Economic Analysis of the M-
DBP Advisory Committee
Recommendations document).
The compliance decision tree
analyses discussed above and
summarized in Table VIII-1 pertain to
large systems serving more than 10,000
persons. The small systems (less than
10,000 population served) decision tree
is likely to be different. As a default.
EPA assumed that the small systems
decision tree would be exactly the same
as that used in the 1994 RIA. The small
systems face a different set of
compliance choices because the current
TTHM standard of 0.10 mg/L (100
Hg/L) does not apply to them; they are
therefore applying DBF controls for the
first time.
C. Rational Cost Estimates
A national cost analysis, based on the
TWG's decision tree analyses discussed
above, is summarized in this section.
The analysis incorporates updated unit
cost estimates for alternative treatment
technologies.
A national cost model has been
developed to evaluate modified Stage 1
decision trees. The total annual cost for
surface water systems in the 1994 RIA
was $645 million per year (in 1992
dollars) or $728 million (in 1997
dollars). These data are presented in
Table VIII-2.
EPA initially assessed the proportion
of the total national cost in the 1994 RIA
that was attributable to enhanced
coagulation. While enhanced
coagulation by itself is not very
expensive in terms of the cost per
household, national costs are large
when it is broadly implemented and its
inexpensive cost per-thousand-gallon is
multiplied by many billions of gallons.
Enhanced coagulation accounted for
$272 million of the total $645 million
per year (42 percent) documented in the
1994 RIA.
When EPA applied the decision tree
predictions derived from the 1996 WIDE
data (Table VIII-1) to the large surface
water system portion of the cost model,
while holding the 1994 decision tree
assumptions constant for small systems,
results indicated a reduction in total
national cost to surface water systems
from $728 million per year to $453
million, of which $135 million is for
enhanced coagulation. Two major
factors cause this drop in costs: (1) the
halving of the number of systems
estimated to employ advanced
technologies, and (2) some systems are
assumed to have already implemented
enhanced coagulation.
The decision tree predictions derived
from the AWWSCo. data were also run
through the national cost model. The
results indicate a total national cost for
surface water systems of $399 million
per year, of which $222 million is
enhanced coagulation. In this scenario,
there are twice as many systems as in
the 1996 WIDE data adopting advanced
technologies, and only half as many able
to comply with no action. The cost
reductions are, however, comparable to
those observed in the scenario based on
the WIDE decision tree. The reasons this
scenario has comparable cost
advantages relate to the emphasis
placed on ozone and chloramines. The
alternate disinfectants are less costly
than the precursor removal strategies
(e.g., GAC, membranes).
The above compliance scenarios and
cost estimates are subject to
considerable uncertainty. Although
there is no better forecasting method
available than case-by-case analysis, the
data employed here consist only of a
few snapshots of each situation. EPA
believes that national costs are lower
than those estimated in the 1994 RIA,
due to Advisory Committee
Recommendations for significant
modifications in the IESWTR and in the
Stage 1 DBPR that would result in
reductions in total national costs. EPA
believes that the order of magnitude
indicated by the WIDE and AWWSCo.
decision tree analyses is reasonable.
BILLING CODE 6560-50-P
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59473
Table VTH-2: A Comparison of 1992 Disinfection By-Product Compliance Cost Forecast in
1992 and 1997 Dollars (in thousands of $s)
< -;-cl*«.\"^'^Xv!*vi^'i;fA*t ffJ"''.-5'
*' f^Afrfit'4'''^ **$M^'**;&C&
.VrfOftlS;..,; v/'.*. •. * ' '.•"*••'•
Utility Cost
Treatment Costs
Total Capital
Total Annual Cost
Annualized Capital
Annual O&M
Monitoring & Reporting Cost
Start-up/One-time Activities
Annual Monitoring
State Costs
Annual Implementation
Total Annualized DBPR Costs1
f!?iipecen^iirl99'f Dollars'
All Water Systems
(Surface Water & Ground Water)
$4,400,000
$1,035,000
$546,000
$489,000
$8,841
$54,924
In April 1997 DdllaW
All Water Systems
(Surface Water & Ground Water)
$4,967,600
$1,168,515
$616,434
$552,081
$9,981
$62,009
$80,224
$1,170,148
$90,572
$1,321,096
Note:
(1) The start-up/one-time activities cost is not included in the total annualized DBPR cost
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59474 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
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BILLING CODE 6560-60-C
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Federal Register / Vol. 62, No. 212 / Monday. November 3, 1997 / Proposed Rules 59475
1. System Level Costs
The unit cost estimates in the
proposal were developed for each of the
different treatment technologies in each
system size category. The unit cost
estimates were derived from a cost
model described in the Cost and
Technology Documents (USEPA, 1992c)
and adjusted after discussion among
TWG members to reflect site-specific
factors (USEPA. 1994b). For systems in
six categories serving greater than
10,000 people, the estimated system-
level costs for achieving compliance
ranged from $0.01/1000 gallons
(chlorine/chloramines) to $1.87/1000
gallons (membrane technology). For
systems in size categories serving less
than 10,000 people the estimated system
level costs for achieving compliance
ranged from $0.03/1000 gallons
(chlorine/chloramines) to $3.49/1000
gallons (membranes). Although some
technologies cost more than $3.49/1000
gallons in the smallest size categories.
such technologies would not be used
because the systems would be able to
achieve compliance with membrane
technology.
Revised unit costs were not available
during the deliberations of the M-DBP
Advisory Committee. Table VIII-4 Is an
analysis of the implications of the
revised decision tree for national costs
using the updated unit cost
assumptions.
BILLING CODE 6560-50-P
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59476 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
of Compliance ($/Y«ar)
BahancedCoagulatren
Chlomie CHossdc
106,2^901
26.4S5.305
41,836,2^
8,927,00^
146,029,198
548^786,721
Table \lU-5: Total AanaBKad Enhanced CoaguJatioa Costs (S/Ye*r)
39S236,8SS
222,342,367
BILLING CODE 6560-50-C
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Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules 59477
2. Household Costs
In the 1994 proposal, EPA estimated
that about 45 million households would
Incur no additional treatment costs for
compliance with the Stage 1 DBPR. Of
the 49 million households incurring
treatment costs for compliance with
Stage 1, EPA estimated that about 99%
(48.6 million households) would incur
costs ranging between $10 per year to
$300 per year and 1% (0.2 million
households) would incur costs of more
than $300 per year. Annual household
costs above $200 are projected
predominantly for small systems that
may be required to install membrane
treatment. Some of these systems could
find that there are less expensive
options available, such as connecting
into a larger regional water system. See
Table VIII-6.
TABLE VIII-6.—AVERAGE COST PER HOUSEHOLD FOR COMPLIANCE TECHNOLOGIES ($/YEAR)
Treatment technology
Clj/NHiCI
EC/NHoCl
Oz/NHjCl
EC+Oz/NHaCI
EC+GAC10
EC+GAC20
Membranes
Total surface water sys-
tems
<1 0,000
$4.36
10.48
14.84
69.10
79.58
0.00
0.00
0.00
413.10
>1 0,000
$0.69
6.70
7.39
8.36
15.06
27.39
74.97
3.06
193.02
Total ground water sys-
tems
<1 0,000
$9.39
0.00
0.00
0.00
0.00
0.00
0.00
0.00
379.91
>1 0,000
$1.10
0.00
0.00
14.74
0.00
0.00
0.00
0.00
220.82
Monitoring and State Implementation
Costs
Since the Advisory Committee made
no recommendations that affected
monitoring or State implementation,
there are no changes to the cost analysis
presented in the 1994 RIA
accompanying the proposed Stage 1
DBPR. The estimates of monitoring and
reporting costs to utilities and
implementation costs to states have
been adjusted for inflation and included
in the total national cost summary
presented in Table VIII-3.
D. DBF Exposure Estimates
The proposed rule included estimates
of the baseline exposures and exposure
after the Stage 1 DBPR for influent
bromide levels; influent and effluent
TOC levels; percent TOC removal;
TTHM levels; and HAAS levels (Table
VIII-7). These data were applicable only
to large surface water systems which
TABLE VIII-7.—BASELINE COMPARISONS
filter but did not soften. Quantitative
changes in exposure for TOC and DBFs
were not predicted for ground water
systems because of insufficient data.
Table VIII-7 presents profiles of
exposure reflecting the baseline
condition and the Stage 1 DBPR. The
change in exposure is characterized in
terms of TOC, TTHM, and HAAS. These
data are applicable only to large systems
(>10,000 population) which filter but do
not soften.
DBPRAM Baseline:
Median
90th
DBPRAM Stags 1:
Median
goth
WIDB 1696:
Median
90th
AWWSCo 1991:
90th
AWWSCo 1892:
90th
Influent
TOC (mg/L)
3.9
8.4
3.9
8.4
3.2
6.1
3.9
7.8
3.9
7.8
% removal
ofTOC(%)
30
57
45
67
32
62
26
58
26
58
TTHMs
(ug/L)
46
90
31
52
40
70
59
83
65
87
HAASs
(W/L)
28
65
20
40
29
60
42
88
34
79
Table VTO-7 presents a tabular
comparison of distributional parameters
for influent TOC. TOC removal, and
distribution system TTHM and HAAS
levels from several different data sets.
The table compares the DBPRAM
baseline assumptions used in the 1994
Stage 1 RIA to the 1996 WIDB data and
the 1991 and 1992 AWWSCo. data.
• The influent TOC levels assumed in
die DBPRAM baseline are similar to
those of the AWWSCo. data set. The
median in both data sets is 3.9 mg/L.
The 1996 WIDB data set, in contrast, has
a median influent TOC of 3.2 mg/L.
• The DBPRAM assumed a baseline
distribution of TOC removal of 30
percent at die median. This is
comparable to a median TOC removal of
32 percent in the 1996 WIDB data.
Median TOC removal in the 1991-92
AWWSCo. data is only 26 percent.
• The DBPRAM baseline assumptions
are roughly similar to die 1996 WIDB
data at the medians for TTHMs (46 vs.
40 ng/1) and HAAS (28 vs 29 u.g/1). The
1991 and 1992 AWWSCo. data are
higher for both TTHM (59 and 65 fig/l)
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59478 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
and HAAS (42 and 34 ng/1) at the
medians.
AWWSCo. data consists of higher
influent TOC levels and higher levels of
DBFs than the 1996 WIDE data. Another
conclusion to be drawn from Table VIII-
7 is that the two different years of data
provided by AWWSCo. are rather
different from each other, illustrating
year-to-year variability.
E. National Benefits Estimates
EPA developed a complete regulatory
impact analysis (May 25, 1994) in
support of the Negotiated Rulemaking
process that ended with the proposed
Stage 1 D/DBP Rule. Since the proposed
rule, new data have become available
that can be used to evaluate the impact
forecasts made in the 1994 RIA. In
addition. Advisory Committee
recommendations, if incorporated into
the rule (and into the companion
IESWTR), would have effects on
national benefit estimates.
The Advisory Committee
recommendations that were evaluated
for possible effects on the national
benefit estimates include: allowance of
ESWTR credit for disinfection prior to
the point of coagulant addition; re-
definition of TOC removal requirements
for enhanced coagulation; and
modification of disinfection
requirements for an ESWTR.
The major new sources of information
that were evaluated included: 1996 data
from the WIDE on TOC, TTHM, HAAS,
and disinfection practices; 1991 and
1992 data on TTHM and HAAS from the
AWWSCo.; as well as TOC data; plant
schematics for ICR utilities; research
data from numerous sources regarding
the efficacy of enhanced coagulation
(Krasner, 1997); and new research
results produced in jar tests by TWG
members documenting the effect of
moving the point of predisinfection
under varying conditions (Krasner,
1997).
1. Recap of Previous Benefits Analysis
The 1992-93 Regulatory Negotiation
Committee, formed under the FACA,
considered the full range of information
and expert opinion available on the
short-and long-term health risks
associated with the complete catalogue
of disinfection byproducts. Committee
members had very different views.
Some believed that cancer risks account
for less than one case of cancer per year,
while others believed that 10,000 cases
per year was the correct order of
magnitude. The lower bound baseline
risk estimate was based on the
maximum likelihood estimates of
toxicological risk (best case estimates as
opposed to upper 95% confidence
bound estimates) associates with TTHM
levels predicted by the DBPRAM
(USEPA, 1994b). Not included in the
lower bound estimate were any risks
resulting from exposure to haloacetic
acids (HAAS), bromate, or chloral
hydrate. The upper bound estimated
risk was based upon a study by Morris
et al. (1992) in which the results from
ten previously published epidemiology
studies were combined. As discussed
above, the use of the Morris study was
questioned by some members of the
negotiating committee.
In the end, the assessment of health
risks was left in this broad range. Based
on the DBPRAM modeling work,
however, the 1994 RIA concludes that
the proposed rule would have reduced
median TTHM and HAA5 exposures by
33 and 29 percent, respectively. TOC
exposure would be reduced by 12
percent at the median (DBF RIA, EPA,
1994. and Table VIII-7). In addition,
this was achieved without triggering
massive shifts to alternative
disinfectants (ozone, chlorine dioxide,
and chloramines), the health effects of
which are not fully understood.
EPA received a comment addressing
the concern for increasing the risk to the
bromate exposure due to the increased
number of systems that will switch to
ozone. The compliance decision tree
that was developed for the 1994 RIA
using the DBPRAM indicated that 17
percent of systems would adopt
advanced treatments (ozone, chlorine
dioxide, GAC, or membranes) in order
to comply with the Stage 1 MCLs. After
a case-by-case reevaluation of the 1996
WIDE and AWWSCo. data sets by the
members of the TWG, it was decided
that fewer systems would require to
shift to advanced technologies (6.5%).
The TWG reevaluated the 1994 decision
tree by considering the bromide levels
for some systems. The TWG assumed
that systems with high raw water
bromide levels will not pick ozonation
as their advanced technology and will
choose other treatments like chlorine
dioxide or GAC; therefore, there is no
expected increase in bromate risk.
2. Current Benefits Analysis
When USEPA considered
modifications to both the IESWTR and
Stage 1 DBPR, the Stage 1 DBPR could
result in reductions in TTHM and
HAAS exposures at the medians that are
in a comparable range to these forecast
in the original Stage 1 proposal. The
extent of TOC removal may be
somewhat less than forecast for the
proposed rule, but not by as much as the
difference in the proposed rule and
NODA decision trees, because some of
the previously estimated use of
advanced technology may have been
driven by increased IESWTR
disinfection requirements. Also, it is
possible that the use of chloramines will
be greater under Advisory Committee
recommendations than under the
proposal. Based on this, USEPA
estimates the level of benefits to be the
same.
F. Cost-Effectiveness
The central requirement of regulatory
impact analyses under Executive Order
12866 is to perform an analysis of net
benefits and to consider the regulatory
alternatives in light of a criterion of
maximizing net benefits. This section
summarizes the problem of regulating
disinfection byproducts in terms of this
economic perspective.
The understanding of net benefits in
DBF control is complicated by the fact
that there is a wide gulf in the scientific
understanding of the health risks.
During the 1992-93 Regulatory
Negotiation, various Negotiating
Committee members believed that
cancer risks due to DBFs ranged from
less than 1 case per year to over 10,000
cases per year. Reflecting this
uncertainty, the 1994 RIA computed an
implied cost per statistical case of
cancer avoided in a range of $400,000 to
$8 billion, fully bracketing—and
underscoring—the range of uncertainty.
In the face of these uncertainties, most
of the analyses undertaken by the 1992-
93 Negotiation Committee, and the
subsequent 1997 M-DBP Advisory
Committee that developed the
recommendations in this Notice, have
used cost-effectiveness and household
costs as a decision framework. In the
1994 RIA, EPA estimated that only 17
percent of systems would have to adopt
expensive advanced treatments to
comply. In the current analysis, that
percentage is projected to be as low as
6.4 percent.
The household cost impacts based on
the M-DBP Advisory Committee
Recommendations and the revised
national cost analysis, are summarized
in Table VIII-6. The results show that
49 million of the 52 million households
affected by the rule will pay about $10
or less per year for compliance. In the
small proportion of systems where
household costs are much greater (up to
several hundreds of dollars per year),
costs are driven by the assumption that
membrane technology will be the
selected treatment. However many of
these systems may find less expensive
means of compliance (e.g., purchased
water). If systems do install membranes,
they may realize additional water
quality and compliance benefits beyond
those associated with DBFs, such as
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Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules 59479
additional pathogen and turbidity
removal.
IX. 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 analytical methods that are
discussed in this Notice were, with two
exceptions, developed and proposed
prior to the enactment of the NTTAA.
Since EPA is now requesting public
comment on potential changes to the
methods for the Stage 1 DBPR, the
Agency felt it would be appropriate to
also explain the requirements of the
NTTAA and seek comment on these
methods and possible modifications to
these methods in that context as well.
EPA's process for developing the
analytical test methods in the proposal
and the potential modifications to those
methods is similar to the requirements
of the NTTAA. EPA performed literature
searches to identify analytical methods
from industry, academia. voluntary
consensus standards bodies, and other
parties that could be used to measure
disinfectants, disinfection byproducts,
and other parameters. In addition. EPA's
development of the methods benefited
from the recommendations of an
Advisory Committee established under
the Federal Advisory Committee Act to
assist the Agency with the Stage 1
DBPR, The Committee made available
additional technical experts who were
well-versed in both existing analytical
methods and new developments in the
field. The results of these efforts formed
the basis for the analytical methods in
the 1994 proposed rule in which EPA
included: six methods for measuring
different disinfection byproducts, of
which five are EPA methods and one is
a voluntary consensus standard; nine
methods for measuring disinfectants, all
of which are voluntary consensus
standards; two voluntary consensus
methods for measuring total organic
carbon fTOC); an EPA method for
measuring bromide; and both
governmental and voluntary consensus
methods for measuring alkalinity. See
proposed DBP regulations (USEPA
1994b) at 38751-38752 (July 29,1994).
Where the only method proposed is an
EPA method, there were either no
voluntary consensus standards available
or the standards did not meet EPA's
data quality objectives.
In this Notice, as discussed in section
V, above, EPA is requesting comment on
possible changes to the proposed
analytic methods, These possible
changes are based on information
received during public comment on the
proposed regulations, or on new
information that has become available
since the 1994 proposal. In general, the
suggested modifications to the proposed
methods are the result of improvements
in both voluntary consensus methods
and EPA methods, or the addition of
methods that have been approved for
other regulatory uses and might be used
for the DBPR (e.g., Specific Ultraviolet
Absorbance (SUVA) and TOC).
In this Notice, EPA discusses
potential changes to the proposed
methods and the reasons for the
changes, and requests public comment
on the possible modifications. The
Agency also solicits comments on
whether there are voluntary consensus
standards that have not been addressed
and should be considered for addition
to the list of approved analytical
methods in the final Stage 1 DBPR.
X. References
1. Adler. I.D. 1993. Synopsis of the in vivo
results obtained with 10 known or
suspected aneugens tested in the CEC
collaborative study. Mutat Res 287:131-
137.
2. Aieta. E.M., Roberts, P.V. and M.
Hernandez. 1984. Determination of
Chlorine Dioxide. Chlorine, Chlorite, and
Chlorate in Water. Jour. Amer. Water
Works Assoc. 76(1):64-70.
3. Allen, J.W., Collins, B.W., and P.A.
Evansky. 1994. Spermatid micronucleus
analysis of trichloroethylene and chloral
hydrate in mice. Mutat Res 323:81-88.
4. Amy, G., et al. 1987. Comparing GPC and
UF for the Molecular Weight
Characterization of Aquatic Organic
Matter. Jour. AWWA, 79:1:43.
5. APHA. Standard Methods for the
Examination of Water and Wastewater,
18th Edition. American Public Health
Association, Washington D.C., 1992.
6. APHA. Standard Methods for the
Examination of Water and Wastewater,
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Association, Washington D.C., 1995.
7. APHA. Standard Methods for the
Examination of Water and Wastewater,
19th Edition, Supplement. American
Public Health Association, Washington
D.C., 1996.
8. Austin, E.W., Parish. J.M., Kinder, D.H.
and R. J. Bull 1996. Lipid peroxidation
and formation of 8-
hydroxydeoxyguanisine from acute
doses halogenated acetic acids. Fundam
ApplToxicol. 31:77-82.
9. Banerji, A.P. and A.O. Fernandes. 1996.
Field bean protease inhibitor mitigates
the sister-chromatid exchanges induced
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spontaneous sister-chromatid exchange
frequency of human lymphocytes in
vitro. Mutat. Res. 360(l):29-35.
10. Bove. F.J. M. Fulcomer, J. Klotz, et al.,
1992a. Public Drinking Water
Contamination and Birthweight, Fetal
Deaths, and Birth Defects: A Cross
Sectional Study (Phase IV-A), New
Jersey Department of Health. April 1992.
11. Bove, F.J. M. Fulcomer, J. Klotz, et al.,
1992b. Public Drinking Water
Contamination and Birthweight, and
Selected Birth Defects: A Case Control
Study (Phase IV-B), New Jersey
Department of Health. May 1992.
12. Bove, F.J., et al. 1995. Public Drinking
Water Contamination and Birth
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14. Cheng, R. C., Yates, R. S., Krasner, S. W.
and S. Liang. 1995. Bench-Scale
Evaluation of the Effects of Seasonal
Change on TOC Removal by Enhanced
Coagulation. Proc. 1995 AWWA Ann.
Conf. (Water Quality), Anaheim, CA,
June 18-22, 1995, pp. 197-216.
15. Chiu, N., Orme-Zavaleta, J., Chiu. A.,
Chen, C., DeAngelo, A., Brattin, W. and
J. Blancato. 1996. Characterization of
cancer risk associated with exposure to
chloroform. Environ. Carcino. and
Ecotox. Revs. C14(2):81-104.
16. Chowdhury, Z. 1997. Presentation to
Technical Work Group January, 1997.
Cincinnati, OH.
17. Clark, S.C., J. Wiginton, and J.T.
Musgrove. 1994. Enhanced Lime
Softening: Is Your TOC Removal Maxed
Out? AWWA Enhanced Coagulation
Workshop, December 1994.
18. Clark, S.C, D. Lawler. 1997. Enhanced
Softening: Calcium, Magnesium, TOC
and Geography. To be presented at the
1997 AWWA Water Quality Technology
Conference, Denver, CO, November 9-
12, 1997.
19. DeAngelo, A. B., Daniel, F. B., Most, B.
M. and G. R. Olsen. 1997. The failure of
monochloroacetic acid and
trichloroacetic acid administered in the
drinking water to produce liver cancer in
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20. Dees, C. and C. Travis. 1994.
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by benzene, toluene, and chloroform.
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21. Dietrich, A.M. 1992. Drinking Water
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Dioxide and Drinking Water Issues.
Houston, Texas; 163-173.
22. Edwards, M. 1997. Predicting DOC
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Jour. AWWA (89:5:78).
23. Edwards, M., Benjamin, M. M. and J. N.
Ryan. 1996. Role of Organic Acidity in
Sorption of Natural Organic Matter
(NOM) to Oxide Surfaces. Colloids and
Surfaces A: Physicochemical and
Engineering Aspects. V., 10:297.
24. Edzwald, J. K., and J. E. Van Benschoten.
1990. Aluminum Coagulation of Natural
Organic Matter. Proc. Fourth Int'l
Gothenburg Symposium on Chemical
Treatment, Madrid, Spain (Oct. 1990).
25. Fox, A.W, Yang, X.. Murli, H.. et al. 1996.
Absence of mutagenic effects of sodium
dichloroacetate. Fundam Appl Toxicol
32:87-95.
26. Fox, T.R, A.M. Schumann, P.G.
Watanabe, B.L. Yano, V.M. Maher and
J.J. McCormick. 1990. Mutational
analysis of the H-RAS oncogene in
spontaneous C57BL/6 x C3H/HE mouse
liver tumors and tumors induced with
genotoxic and nongenotoxic
hepatocarcinogens. Cancer Res.
50(13):4014-9.
27. Fujie, K.. Aoki, T., Ito, Y. and S. Maeda.
1993. Sister-chromatid exchanges
induced by trihalomethanes in rat
erythroblastic cells and their suppression
by crude catechin extracted from green
tea. Mutat Res. 300(3-4):241-246.
28. Fuscoe, J. C., Afshari, A. J., George, M. H.,
DeAngelo, A. B., Tice, R. R., Salman, T.
andJ.W. Allen. 1996. In vivo
genotoxiciry of dichloroacetic acid:
evaluation with the mouse peripheral
blood micronucleus assay and the single
cell gel assay. Environ Mol Mutagen
27:1-9.
29. Gao, P., Thornton-Manning, J. R. and R.A.
Pegram. 1996. Protective effects of
glutathione on bromodichloromethane in
vivo toxicity and in vitro
macromolecular binding in Fischer 344
rats. J. Toxicol. Environ. Health.
49(2):145-59.
30. Gates, D.J. 1988. Improvements in
Chlorine Dioxide Use: A Two-Step
Method for Determining Residual
Oxidants in the Presence of Other
Chlorine Species in Finished Water.
Amer. Water Works Assoc. WQTC-16;
689-703.
31. Gemma, S., Ade, P., Sbraccia, M., Testai,
E. and L. Vittozzi. 1996a. In vitro
quantitative determination of
phospholipid adducts of chloroform
intermediates in hepatic and renal
microsomes from different rodent
strains. Environmental Toxicology and
Pharmacology. 2(2-3):233-242.
32. Gemma. S., Faccioli, S., Chieco, P.,
Sbraccia, M., Testai, E. and L. Vittozzi.
1996b. In vivo CHC13 bioactivation,
toxicokinetics, toxicity, and induced
compensatory cell proliferation in
B6C3F1 male mice. Toxicol. Appl.
Pharmacol. 141(2):394-402.
33. Gibson, D. P., Aardema, M. J. and G. A.
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88. Sofuni, T., Honma, M., Hayashi, M.,
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Goldsworthy and B.E.Butterworth. 1996.
Levels of myc, fos, Ha-ras, met and
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91. Summers, R.S., S.M. Hooper, H.M.
Shukairy, G. Solarik, and D.M. Owen.
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Robert Perciasepe,
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Appendix 1—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/
DBF) 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 ID/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
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59483
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
Urne 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.
2.1 MCLs
MCLs should remain at the levels
proposed: 0.080 mg/1 for TTHMs. 0.060 mg/
1 for HAAS, and 0.010 mg/1 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
percent 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§ 141.135(a)(l) (i)-(lv).
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/1 and TOC
between 2-4 mg/1 by 5 percent (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/1 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:
Alkalinity (mg/1)
TOC (mg/
I)
2-4
4-8
>8
0-<60
35
45
50
60-<120
25
35
40
5120
15
25
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 HAAS 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/1) 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 HAAS levels of at
least 80% of the MCL (0.048 mg/1) 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 HAAS monitoring, the
following provisions apply:
(a) PWSs that have collected HAAS data
under the Information Collection Rule must
use those data to determine the HAAS 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 HAAS data 90 days following the
IESWTR promulgation date, HAAS
monitoring must be conducted for four
quarters.
B. Disinfection profile. A disinfection
profile consists of a compilation of daily
Giardia lamblta 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®, 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 DBFs 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
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59484
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules
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
xither 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
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 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
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 complefed 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.
m. 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 HI, 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. 97-28746 Filed 10-31-97; 8:45 am]
BILLING CODE 6560-6O-P
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