[Federal Register Volume 62, Number 212 (Monday, November 3, 1997)]
[Proposed Rules]
[Pages 59388-59484]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-28746]



[[Page 59387]]

_______________________________________________________________________

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

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

[[Page 59388]]



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 (DBPs) 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 <a href="/cdn-cgi/l/email-protection#78170f551c171b131d0c381d081915191114561d0819561f170e"><span class="__cf_email__" data-cfemail="b5dac298d1dad6ded0c1f5d0c5d4d8d4dcd99bd0c5d49bd2dac3">[email protected]</span></a>.

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:

------------------------------------------------------------------------
                                                Examples of regulated   
                 Category                             entities          
------------------------------------------------------------------------
Public Water System.......................  Community water systems that
                                             add disinfectant or        
                                             oxidant.                   
State Governments.........................  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 Sec. 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

[[Page 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 this Notice, which includes supporting documentation 
as well as printed, paper versions of electronic comments, is available 
for inspection from 9 to 4 p.m., Monday through Friday, excluding legal 
holidays at the Water Docket, U.S. EPA Headquarters, 401 M. St., S.W. 
Washington, D.C. 20460. For access to docket materials, please call 
202/260-3027 to schedule an appointment and obtain the room number.

Copyright Permission

    Supporting documentation reprinted in this document from 
copyrighted material may be reproduced or republished without 
restriction in accordance with 1 CFR 2.6.

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
BAC: 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
DBP: 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
HAA5: Haloacetic acids (five)
IC: 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/l, 1,000 micrograms 
(<greek-m>g)=1 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/l)
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
PODR: 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
WIDB: 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 and 1986 provisions
    2. Changes to initial provisions and new mandates
    D. Regulatory Negotiation Process
    E. Information Collection Rule
    F. Formation of 1997 Federal Advisory Committee
    G. Overview of 1994 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 DBPs 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
III. 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

[[Page 59390]]

    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 HAA5 MCLs
    2. Bromate
    3. Chlorite
VII. 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 DBP 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. DBP 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 (TTHMs) of 0.10 mg/l 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 DBPs. The 
ICR will provide USEPA with additional information on the national 
occurrence in drinking water of (1) chemical byproducts that form when 
disinfectants used for microbial control react with compounds already 
present in source water and (2) disease-causing microorganisms, 
including Cryptosporidium, Giardia, and viruses. The ICR will also 
collect engineering data on how PWSs currently control such 
contaminants. This information is being collected because the 
regulatory negotiation on disinfectants and DBPs concluded that 
additional information was needed to assess the potential health 
problem created by the presence of DBPs and pathogens in drinking water 
and to assess the extent and severity of risk in order to make sound 
regulatory and public health decisions. The ICR will also provide 
information to support regulatory impact analyses for various 
regulatory options, and to help develop monitoring strategies for cost 
effectively implementing regulations.

B. Public Health Concerns To Be Addressed

    In 1990, USEPA's Science Advisory Board, 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 (DBPs). One of the most complex questions facing water 
supply professionals is how to minimize the risks from these DBPs and 
still control microbial contaminants.
    Chemical disinfectants (e.g., chlorine, chloramines, chlorine 
dioxide) are

[[Page 59391]]

added to drinking water to provide continuous disinfection throughout 
the distribution system. There is generally little health concern over 
exposure to the levels of the disinfectant residuals commonly found in 
finished drinking water. A number of organic DBPs, including some 
trihalomethanes (chloroform, bromoform, and bromodichloromethane) and 
some haloacetic acids (e.g., dichloroacetic acid) cause cancer in 
laboratory animals. Other DBPs 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 
DBPs and cardiovascular disease are inconclusive. Animal studies in the 
mid 1980's indicated a potential increase in the serum lipid 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 
lipid 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 DBPs, it is important to 
have information on human exposure to DBPs, information on the toxicity 
of the DBPs and an understanding of the mode of action of toxicity. The 
preamble to the 1994 proposed DBP rule presented information on the 
occurrence and exposure to the Stage 1 DBPs. 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 DBP 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 DBPs for the Stage 2 DBP rule; however, this ICR 
information will not be available in time for the Stage 1 DBP 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 1412(b)(1)(A)).
    The Amendments also require that USEPA, when proposing a NPDWR that 
includes an MCL or treatment technique, publish and seek public comment 
on health risk reduction and cost analyses. The Amendments also require 
USEPA to take into consideration the effects of contaminants upon 
sensitive subpopulations (i.e. infants, children, pregnant women, the 
elderly, and individuals with a history of serious illness), and other 
relevant factors. (Section 1412 (b)(3)(C)).
    The 1996 Amendments also newly require USEPA to promulgate an 
Interim Enhanced SWTR and a Stage I Disinfectants and Disinfection 
Byproducts Rule by November 1998. In addition, the 1996 Amendments 
require USEPA to promulgate a Final Enhanced SWTR and a Stage 2 
Disinfection Byproducts Rule by November 2000 and May 2002, 
respectively (Section 1412(b)(2)(C)).

[[Page 59392]]

    Under the Amendments of 1996, recordkeeping requirements were 
modified to apply to ``every person who is subject to a requirement of 
this title or who is a grantee'' (Section 1445 (a)(1)(A)). Such persons 
are required to ``establish and maintain such records, make such 
reports, conduct such monitoring, and provide such information as the 
Administrator may reasonably require by regulation * * *''.

D. Regulatory Negotiation Process

    In 1992 USEPA initiated a negotiated rulemaking to develop a 
disinfectants/disinfection byproducts rule. The negotiators included 
representatives of State and local health and regulatory agencies, 
public water systems, elected officials, consumer groups and 
environmental groups. The Committee met from November 1992 through June 
1993.
    Early in the process, the negotiators agreed that large amounts of 
information necessary to understand how to optimize the use of 
disinfectants to concurrently minimize microbial and DBP risk on a 
plant-specific basis were unavailable. Nevertheless, the Committee 
agreed that USEPA propose a 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 
DBPs without undermining the control of microbial pathogens. The 
intention was to ensure that drinking water is microbiologically safe 
at the limits set for disinfectants and DBPs and that these chemicals 
do not pose an unacceptable risk at these limits.
    Following months of intensive discussions and technical analysis, 
the Committee recommended the development of three sets of rules: a 
two-staged Disinfectants/Disinfection Byproduct Rule (proposal: 59 FR 
38668, July 29, 1994), 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 DBPs. As part of this effort, the 
Negotiating Committee concluded that the SWTR may need to be revised to 
address health risk from high densities of pathogens in poorer quality 
source waters and from the protozoan, Cryptosporidium. The Committee 
also agreed that the schedules for IESWTR and LTESWTR should be 
``linked'' to the schedule for the Stage 1 DBP Rule to assure 
simultaneous compliance and a balanced risk-risk based implementation. 
The Committee agreed that additional information on health risk, 
occurrence, treatment technologies, and analytical methods needed to be 
developed in order to better understand the risk-risk tradeoff, and how 
to accomplish an overall reduction in risk.
    Finally the Negotiating Committee agreed that to develop a 
reasonable set of rules and to understand more fully the limitations of 
the current SWTR, additional field data were critical. Thus, a key 
component of the regulation negotiation agreement was the promulgation 
of the Information Collection Rule (ICR) noted above and described in 
more detail below.

E. Information Collection Rule

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

F. Formation of 1997 Federal Advisory Committee

    In May 1996, the Agency initiated a series of public informational 
meetings to exchange information on issues related to microbial and 
disinfectants/disinfection byproducts regulations. To help meet the 
deadlines for the IESWTR and Stage 1 DBPR established by Congress in 
the 1996 SDWA Amendments and to maximize stakeholder participation, the 
Agency established the Microbial and Disinfectants/Disinfection 
Byproducts (M-DBP) Advisory Committee under the Federal Advisory 
Committee Act (FACA) on February 12, 1997, to collect, share, and 
analyze new information and data, as well as to build consensus on the 
regulatory implications of this new information. The Committee consists 
of 17 members representing USEPA, State and local public health and 
regulatory agencies, local elected officials, drinking water suppliers, 
chemical and equipment manufacturers, and public interest groups.
    The Committee met five times, in March through July 1997, to 
discuss issues related to the IESWTR and Stage 1 DBPR. Technical 
support for these discussions was provided by a Technical Work Group 
(TWG) established by the Committee at its first meeting in March 1997. 
The Committee's activities resulted in the collection, development, 
evaluation, and presentation of substantial new data and information 
related to key elements of both proposed rules. The Committee reached 
agreement on the following major issues discussed in this Notice and 
the Notice for the IESWTR published elsewhere in today's Federal 
Register: (1) MCLs for TTHMs, HAA5 and bromate; (2) requirements for 
enhanced coagulation and enhanced softening (as part of DBP control); 
(3) microbial benchmarking/profiling to

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provide a methodology and process by which a PWS and the State, working 
together, assure that there will be no significant reduction in 
microbial protection as the result of modifying disinfection practices 
in order to meet MCLs for TTHM and HAA5; (4) disinfection credit; (5) 
turbidity; (6) Cryptosporidium MCLG; (7) removal of Cryptosporidium; 
(8) role of Cryptosporidium inactivation as part of a multiple barrier 
concept and (9) sanitary surveys. The Committee's recommendations to 
USEPA on these issues were set forth in an Agreement In Principle 
document dated July 15, 1997. This document is included with this 
Notice as Appendix 1.

G. Overview of 1994 DBP Proposal

    The proposed Disinfectants and Disinfection Byproducts Stage I Rule 
(DBPI) 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 Giardia lamblia, 
Cryptosporidium, bacteria, and viruses) to be controlled by the IESWTR.
    The proposed Stage 1 DBP rule applied to all community water 
systems (CWSs) and nontransient noncommunity 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 the 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 
dibromochloromethane, 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 haloacetic 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 DBPs: 0.010 mg/L for bromate and 1.0 mg/L for chlorite.
    In addition to proposing MCLGs and MCLs for several DBPs, 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 HAA5 as enhanced 
coagulation or treatment with granular activated carbon with a ten 
minute empty bed contact time and 180 day reactivation frequency 
(GAC10), 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 the 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 the analysis of two classes of organic DBPs: TTHMs (three methods) 
and HAA5 (2 methods). In addition, EPA proposed one method for 
measuring both inorganic DBPs (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 the 
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 DBPs 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

[[Page 59394]]

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 DBPs 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 DBPs (USEPA, 1994a). The expert panel presented the following 
conclusions.

    (A)lthough 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 DBPs. 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 DBPs 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 DBPs 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 DBP rule, they will be very useful in designing 
future epidemiology studies.
    In addition to USEPA's research, the Microbial/DBP Research Council 
(M/DBP 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

[[Page 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 
chlorination byproducts provide an inadequate basis for identifying 
DBPs 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 
DBPs as a reproductive or developmental hazard. Nevertheless, 
additional laboratory animal and epidemiological research should be 
conducted, employing a coordinated multi 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 the 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 Bove 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 DBPs, 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 DBPs. The information 
presented below is a summary of the significant new information for 
several disinfectants and DBPs. 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 DBP 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

[[Page 59396]]

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 the 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 DBP 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 
dibromochloromethane (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 et al., 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, the 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 the 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 DBP 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 that 
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 et al., 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 the 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 the final Stage 1 DBP rule.
    Screening studies have shown the potential of different haloacetic 
acids, including DCA and brominated haloacetic acids, to produce 
reproductive and developmental effects (Linder et al., 1997c; Hunter et 
al., 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 HAA5, 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

[[Page 59397]]

would exceed the theoretical 1 x 10<SUP>-4</SUP> 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 recently 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 the potential implications 
for the regulatory provisions for bromate prior to the 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 currently believes the new published data will 
not impact the MCLGs for BDCM, CDBM, bromoform, chloral hydrate, or 
trichloroacetic acid. However, USEPA is currently 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 the regulatory provisions for these 
DBPs prior to the final rule.

E. Request for Public Comments

    USEPA requests comment on all the new information outlined above 
and its potential impacts on the regulatory provisions for the final 
Stage 1 DBPR and any additional data on the health effects from DBPs 
that need to be considered for the 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 (HAA5) (USEPA, 1994b). In that 
proposal, 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 DBP 
precursors by enhanced coagulation or enhanced softening. The removal 
of total organic carbon (TOC) would be used as a performance indicator 
for DBP 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-1).

     Table III-1.--1994 Proposed Required Removal of TOC by Enhanced    
    Coagulation/Enhanced Softening for Surface-Water Systems <SUP>a Using    
                        Conventional Treatment <SUP>b                        
------------------------------------------------------------------------
                                      Source-water alkalinity, mg/L as  
                                                   CaCO<INF>3                
      Source-water TOC, mg/L      --------------------------------------
                                       0-60       >60-120       >120 <SUP>c  
                                    (percent)    (percent)    (percent) 
------------------------------------------------------------------------
>2.0-4.0.........................         40.0         30.0         20.0
>4.0-8.0.........................         45.0         35.0         25.0
>8.0.............................         50.0         40.0         30.0
------------------------------------------------------------------------
<SUP>a Also applies to utilities that treat groundwater under the influence  
  of surface water.                                                     
<SUP>b Systems meeting at least one of the conditions in Section             
  141.135(a)(1)(i)-(iv) of the proposed rule are not required to operate
  with enhanced coagulation.                                            
<SUP>c Systems practicing precipitative softening must meet the TOC removal  
  requirements in this column.                                          

    The 1994 Stage I Federal Register notice proposed that 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 
the point of continuous disinfection, is <ls-thn-eq>2.0 mg/L (b) when 
the PWS's source water TOC level, prior to any treatment, is <4.0 mg/L; 
the alkalinity is >60 mg/L; and these systems are achieving TTHMs 
<0.040 mg/L and HAA5 <0.030 mg/L, or have made irrevocable financial 
commitments to technologies that will meet these levels; (c) the PWS's 
TTHM annual average is no more than 0.040 mg/L and the HAA5 annual 
average is no more than 0.030 mg/L and the system uses only chlorine 
for disinfection; and (d) PWSs practicing softening and removing at 
least 10 mg/L of magnesium hardness (as CaCO<INF>3</INF>), except those 
that use ion exchange, are not subject to performance criteria for the 
removal of TOC.
    As part of the enhanced coagulation requirements, the proposed rule 
indicated that if a PWS could not meet the 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 the waters that were not expected to meet the 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 the 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 (CaCO<INF>3</INF>), 
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 
the 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 the use of iron 
coagulants in the step 2 jar testing.
    The TOC of each jar-treated water is measured, and then the 
residual TOC is plotted versus alum dosage. The ``point of diminishing 
returns'' (PODR) 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 
<ls-thn-eq>[0.3 mg/L TOC]/[10 mg/L alum]). These data would be used by 
a utility

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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 DBP 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-1 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 type 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) 3 x 3 matrix: For softening plants, is enhanced softening 
properly defined by the percent removals in Table III-1 in this Notice, 
or by 10 mg/L removal of magnesium hardness reported as 
CaCO<INF>3</INF>?
    (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 3 x 3 matrix in 
Table III-1. 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<SUP>-1</SUP>) 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-1 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).

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    In the jar tests of the Raleigh water, an alum dose of 
<difference>35 mg/L resulted in the removal of <difference>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 a jar-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 the 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 
<difference>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.

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    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 alkalinity, mg/L as CaCO<INF>3                 
        Source-water TOC, mg/L         -------------------------------------------------------------------------
                                                  0-60                   >60-120                   >120         
----------------------------------------------------------------------------------------------------------------
>2.0-4.0..............................  <2.0 <SUP>a                   PODR <SUP>b                   N/A <SUP>c                 
                                        PODR                     PODR                     PODR                  
                                        PODR                     STEP 1 <SUP>d                 N/A                   
                                        PODR                     PODR                                           
                                        PODR                                                                    
>4.0-8.0..............................  STEP 1                   PODR                     STEP 1                
                                        STEP 1                   PODR                     STEP 1                
                                        STEP 1                   STEP 1                   PODR                  
                                                                 STEP 1                                         
>8.0..................................  STEP 1                   STEP 1                   STEP 1                
                                        STEP 1                   PODR                     PODR                  
                                        PDOR                     STEP 1                   PODR                  
----------------------------------------------------------------------------------------------------------------
<SUP>a Settled water TOC less than 2.0 mg/L.                                                                         
<SUP>b Point of diminishing returns.                                                                                 
<SUP>c Not amenable to enhanced coagulation.                                                                         
<SUP>d Step 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.

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    In the UNC study, the humic carbon content of the raw waters was 
reasonably correlated (r\2\=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., <ls-thn-eq>2.4 L/mg-m) tended to plateau at high 
alum doses, reflecting that the residual DOC was primarily nonhumic 
organic matter.
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    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.
    b. 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 (1K) 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 <difference> 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 (Krasner et 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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    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 III-9 shows that increasing doses of alum reduced 
the fraction of humic DOC in the residual DOC to 26 percent. In 
addition, the reduction in SUVA closely paralleled the reduction in the 
humic content of the 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.
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    Colorado River water has a greater amount of low-molecular weight 
DOC and somewhat more nonhumic DOC than California State Project Water 
(Krasner et 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 III-10 and III-11). The 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 III-12).

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    Cheng 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 were 
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 either 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 1.a. 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 the point-
to-point method 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 3 x 3 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 the 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 3 x 3 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.

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    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 fractions (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).

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    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 III-14). Assuming a typical 
DOC analytical error of either <plus-minus>0.25 mg/L or <plus-minus>5 
percent, 81 percent of the model predictions were accurately predicted 
within analytical precision.

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    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 3 x 3 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.

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    The next analyses evaluated what TOC removal is ``practical'' to 
achieve in order to better define the 3 x 3 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 III-15 illustrates 
the shape of the curves for the low-alkalinity waters.

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    The significance of the 90th-percentile data point is that 90 
percent of systems (represented by the database) will have a lower 
residual TOC compared to what is predicted by the equations for a given 
coagulant dose.

1. TOC=1.42+2.04 <bullet> e <SUP>-7.15</SUP> <bullet> 
<SUP>Dose (moles/L)</SUP> [for low-TOC, low-alkalinity box]
2. TOC=1.37+2.10 <bullet> e <SUP>-3.92</SUP> <bullet> 
<SUP>Dose (moles/L)</SUP> [for low-TOC, medium-alkalinity box]
3. TOC=2.10+1.27 <bullet> e <SUP>-2.73</SUP> <bullet> 
<SUP>Dose (moles/L)</SUP> [for low-TOC, high-alkalinity box]
4. TOC=1.60+5.38 <bullet> e <SUP>-6.29</SUP> <bullet> 
<SUP>Dose (moles/L)</SUP> [for medium-TOC, low-alkalinity box]
5. TOC=2.11+4.41 <bullet> e <SUP>-3.47</SUP> <bullet> 
<SUP>Dose (moles/L)</SUP> [for medium-TOC, medium-alkalinity box]
6. TOC=2.64+3.30 <bullet> e <SUP>-4.83</SUP> <bullet> 
<SUP>Dose (moles/L)</SUP> [for medium-TOC, high-alkalinity box]
7. TOC=3.22+23.1 <bullet> e <SUP>-2.99</SUP> <bullet> 
<SUP>Dose (moles/L)</SUP> [for high-TOC, low-alkalinity box]
8. TOC=4.88+13.8 <bullet> e <SUP>-3.33</SUP> <bullet> 
<SUP>Dose (moles/L)</SUP> [for high-TOC, medium-alkalinity box]
9. TOC=6.61+6.44 <bullet> e <SUP>-3.57</SUP> <bullet> 
<SUP>Dose (moles/L)</SUP> [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 that 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 III-5.--Controlling Criterion for Enhanced Coagulation for Waters
   Evaluated in Malcolm Pirnie, Inc. Study, Based on Modeling Approach  
------------------------------------------------------------------------
                                             Alkalinity mg/L            
          TOC (mg/L)           -----------------------------------------
                                    0-60         >260-120        >120   
------------------------------------------------------------------------
>2.0-4.0......................  PODR........  PODR.........  PODR       
>4.0-8.0......................  Step 1......  PODR.........  Step 1     
>8.0..........................  Step 1......  Step 1.......  Step 1     
------------------------------------------------------------------------

    Malcolm Pirnie, Inc. next examined SUVA removal curves (Figure III-
16), similar to what was examined by the UNC research team (Figure III-
6).

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    The 90th-percentile SUVA curves were observed to reach asymptotic 
values with increasing coagulant Dose (Figure III-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 TOC equations, the significance of the 90th-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 <bullet> e <SUP>-11.1</SUP> <bullet> 
<SUP>Dose (moles/L)</SUP> [for low-TOC, low-alkalinity box]
b. SUVA=1.8+1. 2 <bullet> e <SUP>-7.9</SUP> <bullet> 
<SUP>Dose (moles/L)</SUP> [for low-TOC, medium-alkalinity box]
c. SUVA=1.4+2.2 <bullet> e <SUP>-9.5</SUP> <bullet> 
<SUP>Dose (moles/L)</SUP> [for low-TOC, high-alkalinity box]
d. SUVA=1.9+2.8 <bullet> e <SUP>-17.5</SUP> <bullet> 
<SUP>Dose (moles/L)</SUP> [for medium-TOC, low-alkalinity box]
e. SUVA=1.8+2.0 <bullet> e <SUP>-5.2</SUP> <bullet> 
<SUP>Dose (moles/L)</SUP> [for medium-TOC, medium-alkalinity box]
f. SUVA=2.1+0.95 <bullet> e <SUP>-6.0</SUP> <bullet> 
<SUP>Dose (moles/L)</SUP> [for medium-TOC, high-alkalinity box]
g. SUVA=2.5+2.8 <bullet> e <SUP>-3.8</SUP> <bullet> 
<SUP>Dose (moles/L)</SUP> [for high-TOC boxes]

    From a theoretical viewpoint, the asymptote of the above equations 
represents the minimum SUVA that could be achieved for a given data set 
(box) of the 3x3 matrix. The dosages for the minimum SUVA are related 
to certain maximum percent TOC removals. However, from a practical 
standpoint, achieving the minimum SUVA could be extremely difficult. An 
alternative approach could be to attempt to reach SUVA values which are 
20 or 25 percent above minimum SUVA indicated by the above equations. 
Equations 1 through 9 and equations a. through g. were combined to 
determine the practical percent TOC removal values that could be 
achieved. The results for ``minimum SUVA+25%'' are shown in Table III-
6.

Table III-6.--TOC Removals (%) at ``Minimum SUVA+25%,'' Based on Malcolm
                      Pirnie, Inc. Modeling Effort                      
------------------------------------------------------------------------
                                                   Alkalinity (mg/L)    
                 TOC (mg/L)                  ---------------------------
                                                0-60    >60-120    >120 
------------------------------------------------------------------------
>2.0-4.0....................................       35        25       15
>4.0-8.0....................................       35        45       20
>8.0........................................       60        55       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 III-7.--TOC Removal at Full-Scale Treatment Plants                            
----------------------------------------------------------------------------------------------------------------
                    TOC >2.0-4.0 mg/L                       Percent of plants that achieve specified TOC removal
----------------------------------------------------------------------------------------------------------------
                                        No. of    Step 1     0-10%      10-20%     20-30%     30-40%      >40%  
          Alkalinity (mg/L)             Plants     TOC%     removal    removal    removal    removal    removal 
----------------------------------------------------------------------------------------------------------------
0-60.................................        14        40         14         14         14         29        *29
>60-120..............................        11        30         36          0         27         18         18
>120.................................         7        20         57         29         14          0          0
----------------------------------------------------------------------------------------------------------------
          TOC >4.0-8.0 mg/L                                                                                     
(4)Percent of plants that achieve                                                                               
 specified TOC removal                                                                                          
                                      --------------------------------------------------------------------------
                                                             0-15%                                              
                                                            removal     15-25%                                  
                                                                       removal     25-35%                       
                                                                                  removal     35-45%            
                                                                                             removal      >45%  
                                                                                                        removal 
----------------------------------------------------------------------------------------------------------------
0-60.................................        18        45          0          0         11          6         83
>60-120..............................         8        35         12         25         25         38          0
>120.................................        13        25         31         31         23         15          0
----------------------------------------------------------------------------------------------------------------
            TOC >8.0 mg/L                                                                                       
(4)Percent of plants that achieve                                                                               
 specified TOC removal                                                                                          
                                      --------------------------------------------------------------------------
                                                              0-20      20-30      30-40      40-50       >50   
----------------------------------------------------------------------------------------------------------------
0-60.................................         2        50          0          0          0          0        100
>60-120..............................         2        40          0          0          0          0        100
>120.................................         1        30         NA         NA        100         NA         NA
----------------------------------------------------------------------------------------------------------------
*Values in bold represent the percentage of systems that achieved full-scale TOC removal that is greater than   
  the proposed step 1 requirements.                                                                             


[[Page 59426]]

    e. Evaluation of ``optimized'' TOC 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 <difference>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 <difference>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.

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    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 
(SUVA<INF>r</INF>) <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 DBP 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 3 x 3 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 DBP 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 settled-water 
SUVA <ls-thn-eq>2.0 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 the greatest difficulty in removing TOC (Figure III-17 and III-
18).

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    The authors indicate some improved TOC 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 III-17 and III-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 III-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 III-9.--Impact of Varying Ferric Coagulant Dose on TOC Removal, 
          Austin, Texas, 4/9/93, 110 mg/L Lime Dose, Jar Tests          
------------------------------------------------------------------------
                                                     Treated            
                                                      water     Treated 
          Ferric sulfate addition (mg/L)           turbidity,  water TOC
                                                       NTU       (mg/L) 
------------------------------------------------------------------------
3................................................        16         2.45
6................................................        15         2.30
9................................................        12         2.46
12...............................................        12         2.23
18...............................................         5.5       2.31
------------------------------------------------------------------------

    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 III-19).

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    Full-scale plant data from St. Louis County Water Company and 
Kansas City, MO Water Services show that water temperature, turbidity, 
and raw water TOC 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 III-10. Impacts of the 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.

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[[Page 59435]]

    b. Shorney 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<SUP>-1</SUP>) 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.

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[[Page 59437]]

    c. Malcolm Pirnie, 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-1 
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 III-
11.

  Table III-11.--Distribution of Responding Plants by TOC Concentration 
------------------------------------------------------------------------
                                                                Number  
                                                               reporting
                                                   Number of  sufficient
                 Raw TOC (mg/L)                     plants      data to 
                                                  responding   calculate
                                                                 %TOC   
                                                                removal 
------------------------------------------------------------------------
0-2.............................................           5           5
>2-4............................................          11           8
>4-8............................................          20          17
>8..............................................           4           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 III-21 (Clark et al., 1997) for the 2-4 mg/L TOC, and 
Figure III-22 for the 4-8 mg/L TOC (Clark et al., 1997).

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    To examine the percentage of plants that would meet the proposed 
requirements, the survey data were analyzed and the results are shown 
in Table III-12. The results in Table III-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 III-12.--Percentage of Softening Plants Meeting Current Proposed 
                              Requirements                              
------------------------------------------------------------------------
                                                  Proposed              
                                                    1994     Percentage 
                 Raw TOC (mg/L)                   required    of plants 
                                                  percent     that met  
                                                  removals  requirements
------------------------------------------------------------------------
>2-4...........................................         20           60 
>4-8...........................................         25           80 
>8.............................................         30           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 III-23) and to 
determine whether a point of diminishing returns can be identified for 
lime addition. Figure III-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.

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[[Page 59442]]

    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 III-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 the treatment 
process. Magnesium hydroxide floc do not act the same as calcium 
carbonate floc either in settling or in sludge treatment and the plant 
design for the two precipitates would be significantly 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 the 
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).

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    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 III-25 (Clark et al., 1997)). With only a 
few outliers and regardless of the percent TOC removal, most plants 
produce finished water with alkalinity between 30 and 60 mg/L as 
CaCO<INF>3</INF>.

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    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:
    <bullet> 28% of plants use free chlorine for both primary and 
secondary disinfection.
    <bullet> 50% of plants use free chlorine/chloramine.
    <bullet> 10% of plants use chloramine.
    <bullet> 7% of plants use chlorine dioxide/chloramine.
    <bullet> 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 <greek-m>g/L level for THMs (see Figure III-26 
(Clark et al., 1997)). All reporting softening plants have average HAA5 
levels below 60 
<greek-m>g/L (see Figure III-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 HAA5 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.

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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 DBP 
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 
CaCO<INF>3</INF>.

  Table III-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 CaCO<INF>3    
                                                                 -----------------------------------------------
                     Source water TOC, mg/L                            0-60a         >60-120 <SUP>a       >120 <SUP>a <SUP>b   
                                                                     (percent)       (percent)       (percent)  
----------------------------------------------------------------------------------------------------------------
>2.0-4.0........................................................            35.0            25.0            15.0
>4.0-8.0........................................................            45.0            35.0            25.0
>8.0............................................................            50.0            40.0           30.0 
----------------------------------------------------------------------------------------------------------------
<SUP>a Not applicable to waters with raw-water SUVA  2.0 L/mg-m.                                                     
<SUP>b Systems practicing precipitative 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 3 x 3 
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 
<ls-thn-eq>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 
Sec. 141.135(a)(1)(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 <ls-thn-eq>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 <ls-thn-eq>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 <ls-thn-eq> 2.0 L/mg-m. 
Also, systems that remove a minimum of 10 mg/L of magnesium hardness 
(as CaCO<INF>3</INF>) 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 
CaCO<INF>3</INF>), 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 HAA5 <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 
DBP 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 III-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 DBPs, 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

[[Page 59450]]

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 DBP Stage I rule discouraged the 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 the 
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 the concentration of TOC and UV absorbing 
compounds, thereby decreasing the precursor concentration and the 
chlorine demand. Thus, analysis supporting the proposed rule concluded 
that many plants would be able to comply with the Stage 1 MCLs for THMs 
and HAA5 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 DBPs 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 the EC step. 
Finally, the analysis underlying the 1994 proposed elimination of the 
preoxidation credit assumed that the addition of disinfectant was 
essentially ``mutually exclusive'' of the goal to reduce DBP formation 
by the removal of TOC. As discussed below, new data developed since 
1994 suggests this may not be the case.
    In the 1994 proposal, preoxidation credit was allowed for some 
systems that met any of the following criteria:

--Credit may be taken prior to precursor removal when the water 
temperature was less than 5  deg.C and the total THM (TTHM) and HAA5 
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 
this credit if the TTHM and HAA5 quarterly averages are no greater than 
0.040 mg/L and 0.030 mg/L, respectively. If these DBP averages are 
higher, then the systems may use a ``C'' of 0.2 mg/L or the measured 
value (whichever is lower) and the actual contact time. The credit is 
allowed from the disinfectant feed point, through a closed conduit, and 
ending at the delivery point in the treatment plant.
--For ozone, disinfection credit would be allowed prior to enhanced 
coagulation, if ozonation is followed by biologically active filtration 
(BAF), to ensure the 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., the chlorine dioxide feed stream must contain 
less than five percent per weight free chlorine residual).

    EPA solicited comments on several issues related to the 
predisinfection credit requirements:

--Whether preoxidation was necessary in water treatment to control the 
various water quality problems such as iron and manganese oxidation, 
control of taste and odor, zebra mussels and Asiatic clams?
--Would the 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 the IESWTR (specifically risk-based disinfection 
requirements). For the reasons outlined in section I.E., the ICR 
monitoring data will not be available for consideration as part of 
developing the IESWTR. In light of this, M/DBP FACA members agreed that 
the IESWTR should include requirements for a disinfection benchmark to 
assure no significant reductions in existing levels of microbial 
inactivation while PWSs complied with the Stage 1 DBP requirements, 
unless they met certain site-specific conditions. In a separate NODA 
concerning the IESWTR published today, EPA describes the 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 HAA5 MCLs. 
This was an issue because MCL compliance predictions in the 1994 
proposal were based on assumptions that (1) TTHM and HAA5 formation 
would be limited by precursor removal, which would limit the 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 that led to the 
recommendation to allow disinfection credit for disinfection used, as 
is currently allowed.
1. ICR Mail Survey--Predisinfection Practices
    To obtain information on the current predisinfection practices of 
systems, a survey was sent out to utilities participating in the ICR. 
The results of the 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 the reasons cited is shown 
below:

[[Page 59451]]



------------------------------------------------------------------------
                                             Number of ``yes'' responses
          Predisinfection reason                    (% of total)        
------------------------------------------------------------------------
Taste and Odor Control....................  114 (35%)                   
Turbidity Control.........................  38 (12%)                    
Algae Growth Control......................  177 (54%)                   
Inorganic Oxidation.......................  104 (32%)                   
Microbial Inactivation....................  222 (67%)                   
Other.....................................  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 microbial inactivation, followed by 
algae control, taste and odor and inorganic oxidation. Seventy-seven 
percent of plants that predisinfected reported that their current 
levels of Giardia 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 the same level of microbial protection 
currently 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 predisinfectant 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 DBP Production
    In developing the 1994 proposal, EPA assumed that the removal of 
precursors by enhanced coagulation or enhanced softening had to precede 
Cl<INF>2</INF>/chloramine addition in order to lead to reduction of 
DBPs. 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 DBP 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 3 x 3 (TOC--alkalinity) matrix 
as estimated from AWWA water industry database (WIDB). 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 HAA5 values that exceed the 0.080 mg/L and 
0.060 mg/L proposed MCLs, respectively. WIDB 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 
(Al<INF>2</INF>(SO<INF>4</INF>)<INF>3</INF><bullet>18H<INF>2</INF>O) 
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 the required percent TOC 
removal in the 3 X 3 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 deg.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-Floc), and (4) at the 
end of sedimentation (Post-Sed). Additionally, the raw uncoagulated 
water was adjusted to the settled water pH and chlorinated. The DBP 
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 <plus-minus> 0.4 mg/L after 3 hours of total contact 
time at ambient pH (6.1-8.1) and laboratory temperature (22 deg.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 DBPs were 
assessed. Settled water was also chlorinated under uniform formation 
conditions (UFC) (Summers et al., 1996) to represent distribution 
system DBP formation. A more detailed experimental approach is 
presented elsewhere (Solarik et al., 1997, Summers et al., 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 HAA5 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 DBPs 
formed after three hours of contact time with free chlorine. The DBP 
concentrations shown in these three figures are not intended to 
represent occurrence levels of DBPs 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 DBP formation 
relative to that formed in the raw uncoagulated water.

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    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 HAA5 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 HAA5, moving the point of chlorination 
downstream in the coagulation, flocculation, 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 
DBPs. While having only a small impact on average for TOX, TTHM, and 
HAA5 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 HAA5 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-
Floc 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 90th 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-
Floc 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 HAA5 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-
Floc 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 HAA5 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-Floc 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 this study, precursor removal was a more 
effective DBP control strategy when used in conjunction with delaying 
the point of chlorination until Mid-Floc 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 3  x  3 enhanced coagulation matrix. This yielded a median increase 
in the percent TOC removal of 14 percent. Table IV.1 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 
HAA5 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 HAA5 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                    
----------------------------------------------------------------------------------------------------------------
                                                                 Median benefit (%)                             
                                   -----------------------------------------------------------------------------
                                            TOX (n=7)                TTHM (n=9)                HAA5 (n=6)       
                                   -----------------------------------------------------------------------------
                                      Baseline     Enhanced     Baseline     Enhanced     Baseline     Enhanced 
                                    coagulation  coagulation  coagulation  coagulation  coagulation  coagulation
----------------------------------------------------------------------------------------------------------------
Pre-RM............................  ...........           11  ...........           17  ...........          4.7
Post-RM...........................          0.3           10          1.6           21          5.3           21
Mid-Floc..........................          3.9           23          8.7           36           14           36
Post-Sed..........................           11           40           21           48           35           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 HAA5, respectively. This can be thought of as in-plant 
DBP formation relative to distribution system formation for systems 
with 3-hour post sedimentation contact.

[[Page 59462]]

Summary

    The results of this study indicate that enhancing the coagulation 
process, while maintaining prechlorination, can result in decreased DBP 
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 HAA5 and to mid flocculation or post 
sedimentation for TOX and TTHM. Compared to prechlorinating three 
minutes before rapid mixing, the greatest DBP 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 HAA5 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 HAA5, respectively, while maintaining 
existing disinfection practice. This analysis also indicated that 
significant precursor removal and DBP reduction can still be achieved 
with predisinfection left in place. Although in most cases the 
reduction in DBP 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 DBP 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 DBPs 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 DBPs 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 DBP rule included the same three methods for analyzing 
chlorine dioxide (ClO<INF>2</INF>) that are approved under the SWTR and 
ICR regulations. Two of these methods, Standard Methods 
4500.ClO<INF>2</INF> C (APHA 1992) and 4500.ClO<INF>2</INF> E (APHA 
1992), are amperometric methods. The third method proposed was Standard 
Method 4500.ClO<INF>2</INF> 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 ClO<INF>2</INF> 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 ClO<INF>2</INF> 
residuals in drinking water and is relatively easy to perform.
    Method 4500.ClO<INF>2</INF> 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.ClO<INF>2</INF> E is a better method because it utilizes 
differences in the physical properties of ClO<INF>2</INF>, as opposed 
to chemical detection of anionic oxychlorocompounds (Aieta et al., 
1984). Therefore, EPA requests comments on omitting Method 
4500.ClO<INF>2</INF> 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 6251B (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 6251B, also be approved for the 
analysis of haloacetic acids under the Stage 1 DBP 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 HAA5 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

[[Page 59463]]

(TTHMs) under 40 CFR 141.24(e). These same methods were proposed under 
the 1994 Stage I DBP proposal. One of the three methods, EPA Method 
551, was revised to Method 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 DBPs. This change was in response to a report 
indicating elevated recoveries of some brominated DBPs 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 Ion Chromatography)(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 <greek-m>g/L). EPA recognized that 
modifications to the method would be necessary to increase the method 
sensitivity. Studies at that 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 <greek-m>g/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 <greek-m>g/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 <greek-m>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 (IC) 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 
<greek-m>g/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 <greek-m>g/
L. Sample analysis time is approximately 30 minutes per sample.
    An IC column's capacity is directly proportional to its operating 
back pressure at a given flow rate and the older IC systems may not be 
able to tolerate the higher back pressures required when using these 
new IC columns. Consequently, in order to perform this analysis, some 
laboratories with IC 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 <greek-m>g/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 <greek-m>L and for Part B is 50 <greek-m>L, 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 DBPs 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 deg.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

[[Page 59464]]

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 <ls-thn-eq>0.5 mg/L and a precision 
of <plus-minus> 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 5310B 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 nm (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 <greek-m>m 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 nm 
(UV<INF>254</INF>), by the dissolved organic carbon (DOC), and 
multiplying by 100:

SUVA = 100 (cm/m) [ UV<INF>254</INF> (cm-<SUP>1</SUP>)/DOC (mg/L)]

    Two separate analytical methods are necessary to make this 
measurement: 1) UV<INF>254</INF> and 2) DOC.
    1. UV<INF>254</INF>. EPA approved Standard Methods 5910 (APHA 1995) 
for measuring UV<INF>254</INF> 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 
UV<INF>254</INF>.
    2. DOC. Standard Methods (19th Edition-Supplement)(APHA 1996) 
defines DOC as the fraction of TOC that passes through a 0.45 
<greek-m>m-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 UV<INF>254</INF> 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 <greek-m>m 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 6251B 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.ClO<INF>2</INF> 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

[[Page 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 Methods 
5310 B, C and D in the Supplement to Standard Methods, 19th edition and 
those same methods in the 19th edition of Standard Methods for 
measuring TOC and DOC.
    6. EPA requests comments on the methods and filtration procedures 
for measuring SUVA.

VI. MCLs for TTHM, HAAs, Chlorite and Bromate

A. 1994 Proposal

    The 1994 proposal for Stage 1 of the DBPR included MCLs for total 
trihalomethanes (TTHMs), the sum of five haloacetic acids (HAA5), 
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 DBP precursors by enhanced coagulation or 
enhanced softening. The removal of total organic carbon (TOC) would be 
used as a performance indicator for DBP 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 DBPs 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 DBPs associated with their usage: bromate 
and chlorite, respectively. Although the theoretical 10<SUP>-4</SUP> 
risk level for bromate is 5 <greek-m>g/L, an MCL of 0.010 mg/L (10 
<greek-m>g/L) was proposed (because available analytical detection 
methods for bromate were reliable only to the projected practical 
quantification limit (PQL) of 10 <greek-m>g/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 <greek-m>g/L]) and whether the PQL for bromate could be lowered 
to 5 <greek-m>g/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 HAA5 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 DBP formation and force systems to install alternative 
disinfectants, or advanced precursor removal to meet TTHM and HAA5 
MCLs. As discussed earlier in today's Notice in Section IV. 
(Disinfection Credit), PWSs can achieve significant reduction in DBP 
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 HAA5 MCLs and no significant reduction in microbial 
protection. The TWG estimated that 6.4% (based on WIDB 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 quantitation 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, with 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.

[[Page 59466]]

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 DBPs. Finally, although the GWDR was not specifically 
addressed during the reg-neg, EPA anticipated that it would be 
promulgated at about the same time as the IESWTR and Stage 1 DBPR.
    EPA proposed a staggered compliance schedule, based on the reg-neg 
results. The Negotiating Committee and EPA believed that such a process 
was needed for the rules to be properly implemented by both States and 
PWSs. Also, EPA proposed a staggered schedule to achieve the greatest 
risk reduction by providing that larger water systems were to come into 
compliance earlier than small systems (to cover more people earlier), 
and surface water systems were to come into compliance earlier than 
ground water systems (since the potential risks of both pathogens and 
DBPs were considered generally higher for surface water systems). Large 
and medium size surface water PWSs (serving at least 10,000 people) 
constitute less than 25% of community water systems using surface water 
and less than 3% of the total number of community water systems, but 
serve 90% of the population using surface water and over 60% of the 
population using water from community water systems. These large PWSs 
are also those with experience in simultaneous control of DBPs and 
microbial contaminants. EPA proposed that these systems be required to 
comply with the Stage 1 DBPR and IESWTR 18 months after promulgation of 
the rules and that States would be required to adopt the rules no later 
than 18 months after promulgation. These 18 month periods were 
prescribed in the 1986 SDWA Amendments.
    Surface water PWSs serving fewer than 10,000 people were to comply 
with the Stage 1 DBPR requirements 42 months after promulgation, to 
allow such systems to simultaneously come into compliance with the 
LTESWTR. This compliance date reflected a schedule that called for the 
LTESWTR to be promulgated 24 months after the IESWTR was promulgated 
and for PWSs then to have 18 months to come into compliance. Such a 
simultaneous compliance schedule was intended to provide the necessary 
protection from any downside microbial risk that might otherwise result 
when systems of this size attempted to achieve compliance with the 
Stage 1 DBPR.
    Ground water PWSs serving at least 10,000 people would also be 
required to achieve compliance with the Stage 1 DBPR 42 months after 
promulgation. A number of these systems, due to recently installing or 
upgrading to meet the GWDR (which EPA planned to promulgate at about 
the same time as the Stage 1 DBPR), were expected to need some period 
of monitoring for DBPs in order to adjust their treatment processes to 
also meet the Stage 1 DBPR standards.
1996 Safe Drinking Water Act Amendments
    The SDWA 1996 Amendments affirmed several key principles underlying 
the M-DBP compliance strategy developed by EPA and stakeholders as part 
of the 1992 Regulatory Negotiation process. First, under Section 
1412(b)(5)(A), Congress recognized the critical importance of 
addressing risk/risk tradeoffs in establishing drinking water standards 
and gave EPA the authority to take such risks into consideration in 
setting MCL or treatment technique requirements. Second, Congress 
explicitly adopted the staggered M-DBP regulatory development schedule 
developed by the Negotiating Committee. Section 1412(b)(2)(C) requires 
that the standard setting intervals laid out in EPA's proposed ICR rule 
be maintained even if promulgation of one of the M-DBP rules was 
delayed. As noted above, this staggered regulatory schedule was 
specifically designed as a tool to minimize risk/risk tradeoff. A 
central component of this approach was the concept of ``simultaneous 
compliance'' which provides that a PWS must comply with new microbial 
and DBP requirements at the same time to assure that in meeting a set 
of new requirements in one area, a facility does not inadvertently 
increase the risk (i.e., the risk ``tradeoff'') in the other area.
    The SDWA 1996 Amendments also changed two statutory provisions that 
elements of the 1992 Negotiated Rulemaking Agreement were based upon. 
As outlined above, the 1994 Stage 1 DBPR and ICR proposals provided 
that 18 months after promulgation large PWSs would comply with the 
rules and States would adopt and implement the new requirements. 
Section 1412(b)(10) of the SDWA as amended now provides that drinking 
water rules shall become effective 36 months after promulgation (unless 
the Administrator determines that an earlier time is practicable or 
that additional time for capital improvements is necessary--up to two 
years). In addition, Section 1413(a)(1) now provides that States have 
24 instead of the previous 18 months to adopt new drinking water 
standards that have been promulgated by EPA.
Discussion
    In light of the 1996 SDWA amendments, developing a compliance 
deadline strategy that encompasses both the Stage 1 DBPR and IESWTR, as 
well the related LTESWTR and Stage 2 DBPR, is a complex challenge. On 
the one hand, such a strategy needs to reflect new statutory 
provisions. On the other, it needs to continue to embody key reg-neg 
principles reflected in both the 1994 ICR and Stage 1 DBPR proposals; 
principles that both Congressional intent and the structure of the new 
Amendments, themselves, indicate must be maintained.
    An example of the complexity that must be addressed is the 
relationship between the principles of risk/risk tradeoff, simultaneous 
compliance, and the staggered regulatory schedule adopted by Congress. 
Under the 1996 SDWA amendments, the staggered regulatory deadlines 
under Section 1412(b)(2)(C) call for the IESWTR and Stage 1 DBPR to be 
promulgated in November 1998 and the LTESWTR in November of 2000. 
However, a complicating factor reflected in the Negotiated Rulemaking 
Agreement of 1992 and contained in the 1994 ICR, IESWTR, and Stage 1 
DBPR proposals, is that Stage 1 applies to all PWSs, while IESWTR 
applies only to PWSs over 10,000, and the LTESWTR covers

[[Page 59467]]

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

                                   Option 1.--Implement 1994 Proposal Schedule                                  
----------------------------------------------------------------------------------------------------------------
                                                       Surface water PWS                   Ground water PWS     
           Rule (promulgation)            ----------------------------------------------------------------------
                                                  <gr-thn-eq>10k            <10k     <gr-thn-eq>10k      <10k   
----------------------------------------------------------------------------------------------------------------
DBP 1 (11/98)............................  5/00.......................         5/02           5/02         11/03
IESWTR (11/98)...........................  5/00.......................           NA             NA            NA
LTESWTR (11/00)..........................  5/02 (if required).........         5/02             NA            NA
GWDR (11/00).............................  NA.........................           NA            (<SUP>1)           (<SUP>1)
----------------------------------------------------------------------------------------------------------------
\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

[[Page 59468]]

not necessary for large and medium surface systems because compliance 
within 18 months is ``practicable''. To maintain simultaneous 
compliance, the Agency would also have to make the same practicability 
determination for small surface water systems in complying with the 
LTESWTR and for ground water systems serving at least 10,000 in 
complying with the GWDR. In addition, the Agency would need to justify 
42 months for small surface water systems and 60 months for small 
ground water systems with disinfection by making a national 
determination that the additional time was required due to the need for 
capital improvements at each of these small systems. EPA also would 
need to articulate a rationale for why States should not be provided 
the statutorily specified 24 months to implement new complex regulatory 
provisions before PWSs are required to comply. Finally, to implement 
this approach, the Agency would be required to modify the timing 
associated with the microbial backstop provision agreed to on July 15, 
1997 by the M-DBP Advisory Committee (since a 18 month schedule would 
not allow time after promulgation for medium surface water systems 
(10,000-99,999) to collect HAA data prior to having to determine 
whether disinfection benchmarking is necessary).
    EPA requests comment on the issues outlined above in connection 
with this option. In particular, the Agency requests comment and 
information to support a finding that compliance by specified systems 
in 18 months is practicable for some rules, and that extensions to 42 
or 60 months for other systems are required to allow for capital 
improvements.

                               Option 2.--Add 18 Months to 1994 Proposal Schedule                               
----------------------------------------------------------------------------------------------------------------
                                                       Surface water PWS                   Ground water PWS     
           Rule (promulgation)            ----------------------------------------------------------------------
                                                  <gr-thn-eq>10k            <10k     <gr-thn-eq>10k      <10k   
----------------------------------------------------------------------------------------------------------------
DBP 1 (11/98)............................  11/01......................        11/03          11/03          5/05
IESWTR (11/98)...........................  11/01......................           NA             NA            NA
LTESWTR (11/00)..........................  11/03 (if required)........        11/03             NA            NA
GWDR (11/00).............................  NA.........................           NA          (\1\)         (\1\)
----------------------------------------------------------------------------------------------------------------
\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 
outlined above, the 1996 SDWA amendments provide that a two year 
extension may be provided by EPA at the national level or by States on 
a case-by-case basis if either EPA or a State determines that 
additional time is necessary for capital improvements. EPA does not 
believe there is data presently in the record for either of these 
rulemakings to support a national determination by the Agency that a 
two-year extension is justified. EPA requests comment on this issue 
and, if a commenter believes such an extension is warranted, requests 
that the comments provide data to support such a position.
    Adding 18 months to the 1994 proposed compliance strategy would 
result in 78 month (six and a half year) compliance period for small 
ground water systems. This is beyond the overall five year compliance 
period established by Congress under Section 1412(b)(10). EPA is not 
aware of a rationale to support this result that is consistent with 
both the objectives of the reg-neg process and the new SDWA amendments; 
however, the Agency

[[Page 59469]]

requests comment on this issue. As discussed below, EPA believes there 
is a reasonable compliance strategy for addressing ground water systems 
that reflects the requirements of the SDWA amendments as well as the 
intent of the reg-neg process.

                 Option 3.--Require Compliance With all Rules Within Three Years of Promulgation                
----------------------------------------------------------------------------------------------------------------
                                                       Surface water PWS                   Ground water PWS     
           Rule (promulgation)            ----------------------------------------------------------------------
                                                  <gr-thn-eq>10k            <10k     <gr-thn-eq>10k      <10k   
----------------------------------------------------------------------------------------------------------------
DBP 1 (11/98)............................  11/01......................        11/01          11/01         11/01
IESWTR (11/98)...........................  11/01......................           NA             NA            NA
LTESWTR (11/00)..........................  11/03 (if required)........        11/01             NA            NA
GWDR (11/00).............................  NA.........................           NA          11/03         11/03
----------------------------------------------------------------------------------------------------------------

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

                     Option 4.--Merge SDWA Provisions With Negotiated Rulemaking Objectives                     
----------------------------------------------------------------------------------------------------------------
                                                       Surface water PWS                   Ground water PWS     
           Rule (promulgation)            ----------------------------------------------------------------------
                                                  <gr-thn-eq>10k            <10k     <gr-thn-eq>10k      <10k   
----------------------------------------------------------------------------------------------------------------
DBP 1 (11/98)............................  11/01......................        11/03          11/03         11/03
IESWTR (11/98)...........................  11/01......................           NA             NA            NA
LTESWTR (11/00)..........................  11/03 (if required)........        11/03             NA            NA
GWDR (11/00).............................  NA.........................           NA          11/03         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 that will result in a final 
GWDR by November 2000, the same date as the Congressional deadline for 
the LTESWTR. Ground water systems would be required to comply with the 
GWDR by November 2003, three years after promulgation, and to assure 
simultaneous compliance with DBP provisions, such systems would be 
required to comply with Stage 1 DBPR requirements by the same date. 
Again, for the reasons outlined under option 2, USEPA believes a five 
year compliance period for ground water systems is necessary and 
appropriate.
    Option 4 assures that ground water systems will be required to 
comply with Stage 1 DBPR provisions at the same time that they comply 
with the microbial provisions of the Ground Water Disinfection Rule 
(GWDR). Successful implementation of this option requires that EPA 
develop and promulgate the GWDR by November 2000 as indicated above. 
The Agency recognizes that this is an ambitious schedule, but believes 
it is necessary to meet the twin objectives of simultaneous 
implementation and consistency with the new statutory compliance 
provisions of the 1996 SDWA. In evaluating this option, the Agency also 
considered the possibility of meeting these twin objectives in a 
somewhat different fashion by delaying final promulgation of the Stage 
I DBP

[[Page 59470]]

rule as it applies ground water systems until the promulgation of the 
GWDR. This alternative possibility would assure simultaneous compliance 
and also provide a ``safety net'' in the event that the GWDR November 
2000 promulgation schedule is delayed. EPA is concerned, however, that 
this approach may not meet or be consistent with new SDWA requirements 
which provide that the Stage I DBPR be promulgated by November 1998. 
The Agency requests comment on this issue.
Recommendation
    EPA has evaluated each of the considerations identified in Options 
1 through 4. On balance, the Agency believes that Option 4 is the 
preferred option. The primary reasons are 1) to allow States at least 
two years to adopt and implement M-DBP rules consistent with new two 
year time frame provided for under the 1996 SDWA amendments, 2) to 
match the compliance schedules for the LTESWTR and Stage 1 DBPR for 
small (<10,000 served) surface water systems to allow time for capital 
improvements and addressing risk-risk tradeoff issues, and 3) to assure 
that all ground water systems simultaneously comply with newly 
applicable microbial and Stage 1 DBPR requirements on the same 
compliance schedule provided for small surface water systems.
Request for Comments
    EPA requests comment on both the compliance schedule options 
discussed above and on any other variations or combinations of these 
options. EPA also requests comment on its preferred option 4 and on the 
underlying rationale for allowing a five year compliance schedule for 
ground water and small surface water systems under the Stage 1 DBPR.

B. Compliance Violations and State Primacy Obligations

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

C. Compliance With Current Regulations

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

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 DBP 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,

[[Page 59471]]

chlorine dioxide, and membranes. Keying on this feature, the 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, HAA5, and predisinfection practices for groups of water systems. 
The 1996 Water Industry Data Base (WIDB) data set provided data for 308 
<SUP>1</SUP> 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.
---------------------------------------------------------------------------

    \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.
---------------------------------------------------------------------------

    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 
the 1994 DBPRAM analyses, and also familiar with the WIDB 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 <greek-m>ug/L or 48 <greek-m>g/L, respectively. 
These numbers are design targets for maximum contaminant levels (MCLs) 
of 80 <greek-m>g/L and 60 <greek-m>g/L, reflecting the variation in DBP 
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 WIDB data 
and the 1991 and 1992 AWWSCo. data.

             Table VIII-1.--Stage 1 DBP Compliance Forecast             
------------------------------------------------------------------------
                                                             Analysis of
                                    1993 stage  Analysis of  AWWSCo 1991-
    Treatment technology to be        1 RIA      1996 WIDB    1992 data 
           implemented              (percent)       data      (percent) 
                                                                        
------------------------------------------------------------------------
Maintain Current Treatment.......           28         39.0           22
Chlorine/Chloramine..............            3         16.6           28
Enhanced Coagulation + Cl<INF>2/NH<INF>2Cl.           10         19.0           35
Enhanced Coagulation + Cl<INF>2.......           43         19.0  ...........
Ozone/Chloramine.................            5          2.2          7.5
Enhanced Coagulation + O<INF>3/NH<INF>2Cl..            6          2.2          7.5
Enhanced Coagulation + GAC10/                                           
 GAC20...........................            6          0.3  ...........
Chlorine Dioxide.................  ...........          1.6  ...........
Membrane.........................            0          0.3  ...........
------------------------------------------------------------------------

    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<SUP>-4</SUP> risk level for Giardia.
    Since the 1994 proposal, the IESWTR requirement to achieve a 
10<SUP>-4</SUP> risk level for Giardia 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 <SUP>2</SUP> 
systems in the 1996 WIDB data set (23.7%) that had either TTHM 
<gr-thn-eq>64 <greek-m>g/l or HAA(5) <gr-thn-eq>48 <greek-m>g/l. 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.
---------------------------------------------------------------------------

    \2\ 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.
---------------------------------------------------------------------------

    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

[[Page 59472]]

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 
WIDB data is the best available source of information from which to 
develop these estimates.
    The 1996 WIDB provides data on influent total organic carbon (TOC), 
effluent TOC, and alkalinity by plant, as well as TTHM and HAA5 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 WIDB results are clearly different, and 
potentially reflect a number of factors: (1) more adverse DBP 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 HAA5 
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 <greek-m>g/
L) does not apply to them; they are therefore applying DBP controls for 
the first time.

C. National 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 WIDB 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 WIDB 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 WIDB 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 WIDB and AWWSCo. decision tree analyses is reasonable.

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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.

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    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)                 
----------------------------------------------------------------------------------------------------------------
                                                                 Total surface water       Total ground water   
                                                                       systems                   systems        
                    Treatment technology                     ---------------------------------------------------
                                                                <10,000      >10,000      <10,000      >10,000  
----------------------------------------------------------------------------------------------------------------
Cl<INF>2/NH<INF>2Cl...................................................        $4.36        $0.69        $9.39        $1.10
Enhanced coagulation........................................        10.48         6.70         0.00         0.00
EC/NH<INF>2Cl....................................................        14.84         7.39         0.00         0.00
Oz/NH<INF>2Cl....................................................        69.10         8.36         0.00        14.74
EC+Oz/NH<INF>2Cl.................................................        79.58        15.06         0.00         0.00
EC+GAC10....................................................         0.00        27.39         0.00         0.00
Chlorine dioxide............................................         0.00        74.97         0.00         0.00
EC+GAC20....................................................         0.00         3.06         0.00         0.00
Membranes...................................................       413.10       193.02       379.91       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. DBP 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 HAA5 
levels (Table VIII-7). These data were applicable only to large surface 
water systems which filter but did not soften. Quantitative changes in 
exposure for TOC and DBPs 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 HAA5. These data are applicable only to 
large systems (>10,000 population) which filter but do not soften.

                                       Table VIII-7.--Baseline Comparisons                                      
----------------------------------------------------------------------------------------------------------------
                                                                                         TTHM s         HAA5s   
                                                              Influent    % removal   (<greek-m>g/  (<greek-m>g/
                                                             TOC (mg/L)   of TOC (%)       L)            L)     
----------------------------------------------------------------------------------------------------------------
DBPRAM Baseline:                                                                                                
    Median................................................          3.9           30            46            28
    90th..................................................          8.4           57            90            65
DBPRAM Stage 1:                                                                                                 
    Median................................................          3.9           45            31            20
    90th..................................................          8.4           67            52            40
WIDB 1996:                                                                                                      
    Median................................................          3.2           32            40            29
    90th..................................................          6.1           62            70            60
AWWSCo 1991:                                                                                                    
    Median................................................          3.9           26            59            42
    90th..................................................          7.8           58            83            88
AWWSCo 1992:                                                                                                    
    Median................................................          3.9           26            65            34
    90th..................................................          7.8           58            87            79
----------------------------------------------------------------------------------------------------------------

    Table VIII-7 presents a tabular comparison of distributional 
parameters for influent TOC, TOC removal, and distribution system TTHM 
and HAA5 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.
    <bullet> The influent TOC levels assumed in the 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.
    <bullet> The DBPRAM assumed a baseline distribution of TOC removal 
of 30 percent at the 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.
    <bullet> The DBPRAM baseline assumptions are roughly similar to the 
1996 WIDB data at the medians for TTHMs (46 vs. 40 <greek-m>g/l) and 
HAA5 (28 vs 29 <greek-m>g/l). The 1991 and 1992 AWWSCo. data are higher 
for both TTHM (59 and 65 <greek-m>g/l)

[[Page 59478]]

and HAA5 (42 and 34 <greek-m>g/l) at the medians.
    AWWSCo. data consists of higher influent TOC levels and higher 
levels of DBPs than the 1996 WIDB 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 WIDB on TOC, TTHM, HAA5, and disinfection practices; 
1991 and 1992 data on TTHM and HAA5 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 (HAA5), 
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 (DBP 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 WIDB 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 HAA5 
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 DBP 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 DBPs 
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 DBPs, such as

[[Page 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 (TOC); 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, 
l994). 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 l994 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.

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and J.J. McCormick. 1990. Mutational analysis of the H-RAS oncogene 
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Other Chlorine Species in Finished Water. Amer. Water Works Assoc. 
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1996a. In vitro quantitative determination of phospholipid adducts 
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32. Gemma. S., Faccioli, S., Chieco, P., Sbraccia, M., Testai, E. 
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84. Shorney, H. L. and S. J. Randtke. 1994. ``Enhanced Lime 
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Influence of Raw Water Quality on Enhanced Coagulation and Softening 
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1996 AWWA Annual Conference, Toronto, Ontario, Canada.
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88. Sofuni, T., Honma, M., Hayashi, M., Shimada, H., Tanaka, N., 
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91. Summers, R.S., S.M. Hooper, H.M. Shukairy, G. Solarik, and D.M. 
Owen. 1996. Assessing DBP Yields: Uniform Formation Conditions, 
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Stile. 1997. Analyzing the Impacts of Predisinfection Through Jar 
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94. Templin, M.V., Jamison, K.C., Wolf, D.C., Morgan, K.T. and B.E. 
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    Dated: October 22, 1997.
Robert Perciasepe,
Assistant Administrator.

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

2.0  Agreement in Principle

    The Microbial and Disinfection By-Products Federal Advisory 
Committee considered the technical and policy issues involved in 
developing a DBP Stage I rule and an IESWTR under the Safe Drinking 
Water Act and recommends that the Environmental Protection Agency 
base the

[[Page 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 time and resources available.
    The USEPA, a party to the negotiations, agrees that:
    1. The person signing this agreement is authorized to commit 
this party to its terms.
    2. EPA agrees to hold a meeting in July 1997 following 
circulation of a second draft of the NODA to obtain comments from 
the parties and the public on the extent to which the applicable 
sections of the draft NODA are consistent with the agreements below.
    3. Each party and individual signatory that submits comments on 
the NODA agrees to support those components of the NODA that reflect 
the agreements set forth below. Each party and individual signatory 
reserves the right to comment, as individuals or on behalf of the 
organization he or she represents, on any other aspect of the Notice 
of Data Availability.
    4. EPA will consider all relevant comments submitted concerning 
the Notice(s) of Proposed Rulemaking and in response to such 
comments will make such modifications in the proposed rule(s) and 
preamble(s) as EPA determines are appropriate when issuing a final 
rule.
    5. Recognizing that under the Appointments Clause of the 
Constitution governmental authority may be exercised only by 
officers of the United States and recognizing that it is EPA's 
responsibility to issue final rules, EPA intends to issue final 
rules that are based on the provisions of the Safe Drinking Water 
Act, pertinent facts, and comments received from the public.
    6. Each party agrees not to take any action to inhibit the 
adoption of final rule(s) to the extent it and corresponding 
preamble(s) have the same substance and effect as the elements of 
this agreement in principle.

2.1 MCLs

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

2.2 Enhanced Coagulation

    The proposed enhanced coagulation provisions should be revised 
as follows:
    a. The top row of the TOC removal table (3x3 matrix) should be 
modified for systems that practice enhanced coagulation by lowering 
the TOC removal percentages by 5 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 Sec. 141.135(a)(1) (i)-(iv).
    c. For a system required to practice enhanced coagulation or 
enhanced softening, the use of a finished water SUVA < 2.0 liter/mg-
m should be added as a step 2 procedure. Such a criterion would be 
in addition to the proposed step 2 procedure, not in lieu of it.
    d. The proposed TOC removals for softening systems should be 
modified by lowering the value for TOC removal in the matrix at 
alkalinity > 120 mg/l and TOC between 2-4 mg/l by 5 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/l as part of any 
step 2 procedure.
    f. There is no need to separately address softening systems in 
the 3x3 matrix or the Step 1 regulatory language, which was 
identical to enhanced coagulation regulatory language in the 
proposed D/DBPR. The revised matrix should appear as follows:

------------------------------------------------------------------------
                                                                        
------------------------------------------------------------------------
                                                                        
(2) Alkalinity (mg/l)                                                   
------------------------------------------------------------------------
TOC (mg/l).............................      0-<60    60-<120  <gr-thn-e
                                                                    q120
2-4....................................         35         25         15
4-8....................................         45         35         25
>8.....................................         50         40         30
------------------------------------------------------------------------

2.3  Microbial Benchmarking/Profiling

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

2.4  Disinfection Credit

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

2.5 Turbidity

    Turbidity Performance Requirements. For all surface water 
systems that use conventional treatment or direct filtration, serve 
more than 10,000 people, and are required to filter: (a) the 
turbidity level of a system's combined filtered water at each plant 
must be less than or equal to 0.3 NTU in at least 95 percent of the 
measurements taken each month and, (b) the turbidity level of a 
system's combined filtered water at each plant must at no time 
exceed 1 NTU. For both the maximum and the 95th percentile 
requirements. Compliance shall be determined based on measurements 
of the combined filter effluent at four-hour intervals.
    Individual Filter Requirements. All surface water systems that 
use rapid granular filtration, serve more than 10,000 people, and 
are required to filter shall conduct continuous monitoring of 
turbidity for each individual filter and shall provide an exceptions 
report to the State on a monthly

[[Page 59484]]

basis. Exceptions reporting shall include the following: (1) any 
individual filter with a turbidity level greater than 1.0 NTU based 
on 2 consecutive measurements fifteen minutes apart; and (2) any 
individual filter with a turbidity level greater than 0.5 NTU at the 
end of the first 4 hours of filter operation based on 2 consecutive 
measurements fifteen minutes apart. A filter profile will be 
produced if no obvious reason for the abnormal filter performance 
can be identified.
    If an individual filter has turbidity levels greater than 1.0 
NTU based on 2 consecutive measurements fifteen minutes apart at any 
time in each of 3 consecutive months, the system shall conduct a 
self-assessment of the filter utilizing as guidance relevant 
portions of guidance issued by the Environmental Protection Agency 
for Comprehensive Performance Evaluation (CPE). If an individual 
filter has turbidity levels greater than 2.0 NTU based on 2 
consecutive measurements fifteen minutes apart at any time in each 
of two consecutive months, the system will arrange for the conduct 
of a CPE by the State or a third party approved by the State.
    State Authority. States must have rules or other authority to 
require systems to conduct a Composite Correction Program (CCP) and 
to assure that systems implement any follow-up recommendations that 
result as part of the CCP.

2.6  Cryptosporidium MCLG

    EPA should establish an MCLG to protect public health. The 
Agency should describe existing and ongoing research and areas of 
scientific uncertainty on the question of which species of 
Cryptosporidium represents a concern for public health (e.g. parvum, 
muris, serpententious) and request further comment on whether to 
establish an MCLG on the genus or species level.
    In the event the Agency establishes an MCLG on the genus level, 
EPA should make clear that the objective of this MCLG is to protect 
public health and explain the nature of scientific uncertainty on 
the issue of 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:
    <bullet> Data and research needs and limitations (e.g. 
occurrence, treatment, viability, active disease surveillance, 
etc.);
    <bullet> Technology and methods capabilities and limitations;
    <bullet> Removal and inactivation effectiveness;
    <bullet> Risk tradeoffs including risks of significant shifts in 
disinfection practices;
    <bullet> Cost considerations consistent with the SDWA;
    <bullet> Reliability and redundancy of systems;
    <bullet> Consistency with the requirements of the Act.

2.9  Sanitary Surveys

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

I. Definition

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

II. Frequency

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

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

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

III. Follow Up

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

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

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

Signed By:

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

[FR Doc. 97-28746 Filed 10-31-97; 8:45 am]
BILLING CODE 6560-50-P


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