59388 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules

ENVIRONMENTAL PROTECTION

AGENCY

40 CFR Parts 141 and 142

[WH–FRL–5915–3]

National Primary Drinking Water

Regulations: Disinfectants and

Disinfection Byproducts Notice of Data

Availability

AGENCY: U.S. Environmental Protection

Agency (USEPA).

ACTION: Notice of data availability.

SUMMARY: In 1994 USEPA proposed a

Stage 1 Disinfectants/Disinfection

Byproducts Rule (DBPR) to reduce the

level of exposure from disinfectants and

disinfection byproducts (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 MicrobialDisinfection/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 owdocket@epamail.epa.gov.

FOR FURTHER INFORMATION CONTACT: The

Safe Drinking Water Hotline, Telephone

(800) 426–4791. The Safe Drinking

Water Hotline is open Monday through

Friday, excluding Federal holidays,

from 9:00 am to 5:30 pm Eastern Time.

For technical inquiries, contact Thomas

Grubbs or William Hamele, Office of

Ground Water and Drinking Water (MC

4607), U.S. Environmental Protection

Agency, 401 M Street SW, Washington

DC 20460; telephone (202) 260–7270

(Grubbs) or (202) 260–2584 (Hamele).

Regional Contacts

I. Kevin Reilly, Water Supply Section,

JFK Federal Bldg., Room 203, Boston,

MA 02203, (617) 565–3616

II. Michael Lowy, Water Supply Section,

290 Broadway, 24th Floor, New York,

NY 10007–1866, (212) 637–3830

III. Jason Gambatese, Drinking Water

Section (3WM41), 841 Chestnut

Building, Philadelphia, PA 19107,

(215) 566–5759

IV. David Parker, Water Supply Section,

345 Courtland Street, Atlanta, GA

30365, (404) 562–9460

V. Kimberly Harris (micro), Miguel Del

Toral (DBP), Water Supply Section, 77

W. Jackson Blvd., Chicago, IL 60604,

(312) 886–4239 (Harris), (312) 886–

5253 (Del Toral)

VI. Blake L. Atkins, Team Leader, Water

Supply Section, 1445 Ross Avenue,

Dallas, TX 75202, (214) 665–2297

VII. Stan Calow, State Programs Section,

726 Minnesota Ave., Kansas City, KS

66101, (913) 551–7410

VIII. Bob Clement, Public Water Supply

Section, (8WM–DW), 999 18th Street,

Suite 500, Denver, CO 80202–2466,

(303) 312–6653

IX. Bruce Macler, Water Supply Section,

75 Hawthorne Street, San Francisco,

CA 94105, (415) 744–1884

X. Wendy Marshall, Drinking Water

Unit, 1200 Sixth Avenue (OW–136),

Seattle, WA 98101, (206) 553–1890

SUPPLEMENTARY INFORMATION:

Regulated Entities

Entities potentially regulated by the

Stage 1 DBPR are public water systems

that add a disinfectant or oxidant.

Regulated categories and entities

include:

Category Examples of regulated

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 § 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
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules 59389

or title of the Federal Register.

Comments and data will also be

accepted on disks in WordPerfect in 5.1

or WP6.1 or ASCII file format.

Electronic comments on this Notice may

be filed online at many Federal

Depository Libraries. Commenters who

want EPA to acknowledge receipt of

their comments should include a selfaddressed, 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

(μg)=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
59390 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules

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
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules 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 Byproducts (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)).
59392 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules

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 ‘‘longterm’’ 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
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discusses the new epidemiological and

laboratory toxicology studies. In

addition, USEPA has developed

summaries of this new information and

included these documents in the Docket

for this action as ‘‘Summaries of New

Health Effects Data’’ (USEPA, 1997b).

A. Cancer Epidemiology Studies

The preamble to the proposed rule

discussed several cancer epidemiology

studies that had been conducted over

the past 20 years on chlorinated

drinking water (see USEPA, 1994b). At

the time of the proposed rule, there was

disagreement among the members of the

Negotiating Committee on the

conclusions to be drawn from the cancer

epidemiology studies. Some members of

the Committee felt that the cancer

epidemiology data, taken in conjunction

with the results from toxicological

studies, provide an ample and sufficient

weight of evidence to conclude that

exposure to 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 interviewbased 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
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules 59395

and developmental effects and a strategy

developed by the panel for related shortterm 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 shortand 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 populationbased 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 crosssectional 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 twogeneration 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
59396 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules

chlorine dioxide with certain

qualifications and reservations. As cited

above, the Committee agreed that a twogeneration 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 reexamined 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
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would exceed the theoretical 1×10¥4

lifetime excess cancer risk level for

bromate of 5 ug/L. Since the proposal,

several toxicology studies have been

completed on bromate, including assays

for reproductive and developmental

effects (Wolfe and Kaiser, 1996).

USEPA has 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 a USING CONVENTIONAL TREATMENT b

Source-water TOC, mg/L

Source-water alkalinity, mg/L as CaCO3

0–60

(percent)

>60–120

(percent)

>120 c

(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

aAlso applies to utilities that treat groundwater under the influence of surface water.

bSystems 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. cSystems 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 ≤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 CaCO3),

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 pilotscale 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 (CaCO3), 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

≤[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 benchscale 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) 3×3 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

CaCO3?

(2) Use of ferrous salts: Can ferrous

salts be used at softening pH levels to

further enhance TOC removals?

(3) Step 2: Whether data are available

on the use of ferrous salts in the

softening process which can help define

a step 2 for softening? What is the

definition of Step 2?

B. New Information on Enhanced

Coagulation and Enhanced Softening

since 1994 Proposal

Since the 1994 proposal, there has

been considerable research on a number

of enhanced coagulation and enhanced

softening issues highlighted above in a

wide variety of waters nationwide. A

summary of the results of some of the

studies and surveys are included below.

Studies of enhanced coagulation are

covered first, followed by discussion of

enhanced softening studies. Note that a

number of the softening studies looked

at TOC removal in essentially the same

framework as is used for enhanced

coagulation, with emphasis on the

coagulant and lime dose and geared

toward finding a similar format for step

2 enhanced softening as was defined for

enhanced coagulation. A number of

these studies focused on the benefits of

increased lime or coagulant doses in

removing TOC in softening systems.

Results of these studies generally

showed that percent TOC removal is

dependent on the raw water.

1. New Data on Enhanced Coagulation

a. UNC Enhanced Coagulation Study.

To address many of the aforementioned

issues, the University of North Carolina

(UNC) at Chapel Hill, with funding from

the Water Industry Technical Action

Fund (WITAF), performed an enhanced

coagulation study (Singer et al., 1995).

The UNC research team evaluated a

wide range of waters nationwide, which

included at least three waters in each

box of the 3×3 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¥1) divided by the dissolved

organic carbon (DOC) concentration

(measured as mg/L). Typically, SUVA

values <3 L/mg-m are representative of

largely nonhumic material, whereas

SUVA values in the range of 4–5 L/mmg 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 ∼35 mg/L resulted in the

removal of ∼47 percent of the TOC,

where the proposed step 1 TOC removal

for this water was predicted to be 45

percent. The PODR, based on the slope

criterion of 0.3 mg/L TOC/10 mg/L of

alum, was realized at 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), highalkalinity (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 ∼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-tohigh-TOC waters with low alkalinity.

The UNC study suggested that a

significant number of waters (especially

low-TOC, high-alkalinity waters) would

probably need to use the step 2 protocol

to establish alternative performance

criteria.

TABLE III–2.—CONTROLLING CRITERION FOR ENHANCED COAGULATION FOR WATERS EVALUATED IN UNC STUDY, BASED

ON 1994 PROPOSED RULE CRITERIA

Source-water TOC, mg/L

Source-water alkalinity, mg/L as

CaCO3

0–60 >60–120 >120

>2.0–4.0 ......................................................................................................................................................... <2.0 a

PODR

PODR

PODR

PODR

PODR b

PODR

STEP 1 d

PODR

N/Ac

PODR

N/A

>4.0–8.0 ......................................................................................................................................................... STEP 1

STEP 1

STEP 1

PODR

PODR

STEP 1

STEP 1

STEP 1

STEP 1

PODR

>8.0 ................................................................................................................................................................ STEP 1

STEP 1

PDOR

STEP 1

PODR

STEP 1

STEP 1

PODR

PODR

aSettled water TOC less than 2.0 mg/L.

bPoint of diminishing returns.

c Not amenable to enhanced coagulation.

dStep 1 required percent removal of TOC.

White and co-workers (1997)

examined the relationship between the

percent humic (hydrophobic) content of

the raw waters in the UNC study and

the maximum percent removal of DOC

achieved at the high alum doses where

little additional TOC removal was

observed. Figure III–4 shows that waters

with relatively high levels of humic

material tended to exhibit higher

degrees of DOC removal than those with

low humic content. Figure III–5 shows

that waters that contained high initial

nonhumic (hydrophilic) DOC

concentrations tended to have high

residual DOC concentrations following

coagulation.

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In the UNC study, the humic carbon

content of the raw waters was

reasonably correlated (r2=0.74) with

their SUVA values (White et al., 1997).

Figure III–6 shows that waters with high

initial SUVA values (i.e., 3.4–5.7 L/mgm) 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., ≤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 ∼ 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/mmg, 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 coworkers 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

3×3 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 3×3

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 rawwater 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 ±0.25 mg/L or ±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 3×3 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 3×3 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 ‘‘90thpercentile’’ 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 90thpercentile 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 • e ¥7.15 • Dose (moles/L)

[for low-TOC, low-alkalinity box]

2. TOC=1.37+2.10 • e ¥3.92 • Dose (moles/L)

[for low-TOC, medium-alkalinity

box]

3. TOC=2.10+1.27 • e ¥2.73 • Dose (moles/L)

[for low-TOC, high-alkalinity box]

4. TOC=1.60+5.38 • e ¥6.29 • Dose (moles/L)

[for medium-TOC, low-alkalinity

box]

5. TOC=2.11+4.41 • e ¥3.47 • Dose (moles/L)

[for medium-TOC, mediumalkalinity box]

6. TOC=2.64+3.30 • e ¥4.83 • Dose (moles/L)

[for medium-TOC, high-alkalinity

box]

7. TOC=3.22+23.1 • e ¥2.99 • Dose (moles/L)

[for high-TOC, low-alkalinity box]

8. TOC=4.88+13.8 • e ¥3.33 • Dose (moles/L)

[for high-TOC, medium-alkalinity

box]

9. TOC=6.61+6.44 • e ¥3.57 • Dose (moles/L)

[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

TOC (mg/L)

Alkalinity 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 • e ¥11.1 • Dose (moles/L)

[for low-TOC, low-alkalinity box]

b. SUVA=1.8+1. 2 • e ¥7.9 • Dose (moles/L)

[for low-TOC, medium-alkalinity

box]

c. SUVA=1.4+2.2 • e ¥9.5 • Dose (moles/L)

[for low-TOC, high-alkalinity box]

d. SUVA=1.9+2.8 • e ¥17.5 • Dose (moles/L)

[for medium-TOC, low-alkalinity

box]

e. SUVA=1.8+2.0 • e ¥5.2 • Dose (moles/L)

[for medium-TOC, mediumalkalinity box]

f. SUVA=2.1+0.95 • e ¥6.0 • Dose (moles/L)

[for medium-TOC, high-alkalinity

box]

g. SUVA=2.5+2.8 • e ¥3.8 • Dose (moles/L)

[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

TOC (mg/L)

Alkalinity (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 moderateTOC 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

Alkalinity (mg/L) No. of

Plants

Step 1

TOC%

0–10%

removal

10–20%

removal

20–30%

removal

30–40%

removal

>40% 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 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 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.
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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 ∼10–20 times the

TOC level. Thus, a water with 3 mg/L

TOC might use up to 30–60 mg/L of

coagulant (with or without acid), but

would not use 100 mg/L of coagulant

full-scale. However, a water with 10 mg/

L TOC could use 100 mg/L or more of

coagulant given the aforementioned

∼10–20 multiplier for coagulant dose

and TOC. A dose of this magnitude is

discouraged because the NSF limits on

aluminum sulfate and ferric chloride are

150 mg/L and 250 mg/L, respectively.

Because these experiments were

performed without these acid and

coagulant dose limits as constraints,

some waters were evaluated with more

realistic chemical doses in the PODR

experiments. A judgment was made in

deciding which set of conditions was

the most realistic for each water

evaluated. With these elements in mind,

an assessment was made as to which

experiment was the most appropriate

(controlling criteria) for each water. In

some cases, a source water was tested

more than once. If the identical sample

of water (same TOC, SUVA, alkalinity)

was coagulated with different

coagulants, with or without acid, the

highest TOC removal for that water was

chosen, as many systems enhancing

their coagulation process are also

evaluating switching the type of

coagulant.

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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-bycase data, to segment out raw waters

with SUVA (SUVAr) <2.0 L/mg-m

during the analyses of the optimized

coagulation database. This decision was

made because including a significant

number of low-SUVA waters in the

analysis of the boxes results in lowering

the amount of TOC that 90 percent of

the systems in that box can remove.

Thus, the TWG decided to examine

what TOC removal could be

accomplished by the medium-and highSUVA 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 rawwater 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 Committeebased 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

≤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 jartest 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

Ferric sulfate addition (mg/L)

Treated

water turbidity, NTU

Treated

water

TOC

(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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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¥1) divided by the DOC

concentration (mg/L). Typically, SUVA

values <3 L/mg-m are representative of

largely non-humic material, whereas

SUVA values in the range of 4–5 L/mgm 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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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

Raw TOC (mg/L)

Number

of plants

responding

Number

reporting

sufficient

data to

calculate

%TOC

removal

0–2 ............................ 5 5

TABLE III–11.—DISTRIBUTION OF RESPONDING PLANTS BY TOC CONCENTRATION—Continued

Raw TOC (mg/L)

Number

of plants

responding

Number

reporting

sufficient

data to

calculate

%TOC

removal

>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

Raw TOC (mg/L)

Proposed

1994 required

percent

removals

Percentage of

plants

that met

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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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 CaCO3.

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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:

• 28% of plants use free chlorine for

both primary and secondary

disinfection.

• 50% of plants use free chlorine/

chloramine.

• 10% of plants use chloramine.

• 7% of plants use chlorine dioxide/

chloramine.

• 5% of plants use ozone/chloramine.

In spite of the fact that some 78% of

softening plants are using free chlorine

for at least a portion of their

disinfection, the reported yearly average

THMs indicate that 90 percent of plants

are currently meeting an 80 μg/L level

for THMs (see Figure III–26 (Clark et al.,

1997)). All reporting softening plants

have average HAA5 levels below 60

μg/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

CaCO3.

TABLE III–13.—1997 PROPOSED REQUIRED REMOVAL OF TOC BY ENHANCED COAGULATION/ENHANCED SOFTENING FOR

SURFACE-WATER SYSTEMS USING CONVENTIONAL TREATMENT

Source water TOC, mg/L

Source water alkalinity, mg/L as CaCO3

0–60a

(percent)

>60–120 a

(percent)

>120 a b

(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

a Not applicable to waters with raw-water SUVA ≤ 2.0 L/mg-m. bSystems 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/mgm, the TWG felt that 90 percent of the

systems treating such waters will be

able to comply with the revised step 1

TOC removal levels.

The Committee recommended that

waters with raw-water SUVA ≤2.0 L/mgm be given an exemption to enhanced

coagulation and enhanced softening.

SUVA is an indicator of the humic

content of a water. Coagulation removes

humic matter, so waters with low-SUVA

values contain primarily nonhumic

matter, which is not amenable to

enhanced coagulation. The use of a raw

water SUVA < 2.0 liter/mg-m as a

criterion for not requiring a system to

practice enhanced coagulation or

softening should be added to those

proposed in § 141.135(a)(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 ≤2.0 L/mg-m.

At this point, the residual TOC is

mainly composed of nonhumic matter

that is not amenable to enhanced

coagulation; therefore, it is not

productive to add additional coagulant.

Because oxidants can destroy UV, but

not TOC, SUVA must be determined on

water that has not been exposed to

oxidants. Thus, using a settled-water

SUVA ≤2.0 L/mg-m as a PODR should

be done on jar-tested water (as the slope

criterion is done) unless the full-scale

plant is not using preoxidation/

predisinfection. The TWG believes that

these revised requirements will result in

a limited amount of transactional costs

for the PWSs and their primacy

agencies. The Committee recommended

this option to EPA.

Enhanced softening systems that

cannot meet the removal percentages

specified in the TOC removal matrix

must demonstrate that they have met

alternative performance criteria, e.g.,

depressed the alkalinity to a minimum

level or lowered settled water SUVA ≤

2.0 L/mg-m. Also, systems that remove

a minimum of 10 mg/L of magnesium

hardness (as CaCO3) from their raw

water are exempt for enhanced softening

requirements. Lime softening plants

would not be required to perform limesoda ash softening, and no softening

plant will be required to lower treated

effluent alkalinity below 40 mg/L (as

CaCO3), 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 postfiltration) are discussed below. Prefiltration 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
59450 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules

coagulation process. EPA solicits

comment on where the TOC compliance

monitoring point should be located.

EPA also requests comment on the

modifications to enhanced coagulation

TOC removal concentrations and other

provisions for enhanced coagulation

outlined above. Finally, EPA requests

comment on the modifications to the

requirements for enhanced softening.

IV. Disinfection Credit

A. 1994 Proposal

The proposed 1994 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 °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 riskbased 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:
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Predisinfection reason

Number of

‘‘yes’’ responses

(% 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 Cl2/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

(Al2(SO4)3•18H2O) was used as the

coagulant for all waters and two alum

doses were examined for 14 of the 16

waters evaluated. The baseline dose was

set at the level required for turbidity

control, while a second increased dose

was set at the level necessary to meet

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°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 (PostSed). 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 ± 0.4 mg/

L after 3 hours of total contact time at

ambient pH (6.1–8.1) and laboratory

temperature (22°C). The 3 hour reaction

time is representative of that of a typical

coagulation, flocculation and

sedimentation process train. At the end

of the 3 hour incubation time, the

reaction was quenched and 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 × 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

coagulation

Enhanced

coagulation

Baseline

coagulation

Enhanced

coagulation

Baseline

coagulation

Enhanced

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.
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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 (ClO2) that are

approved under the SWTR and ICR

regulations. Two of these methods,

Standard Methods 4500.ClO2 C (APHA

1992) and 4500.ClO2 E (APHA 1992),

are amperometric methods. The third

method proposed was Standard Method

4500.ClO2 D (APHA 1992), a

colorimetric method using the color

indicator N,N-diethyl-pphenylenediamine (DPD).

EPA received several comments

stating that these methods to calculate

ClO2 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

ClO2 residuals in drinking water and is

relatively easy to perform.

Method 4500.ClO2 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.ClO2 E is a better

method because it utilizes differences in

the physical properties of ClO2, as

opposed to chemical detection of

anionic oxychlorocompounds (Aieta et

al., 1984). Therefore, EPA requests

comments on omitting Method

4500.ClO2 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 liquidliquid (micro) extraction with methyl-tbutyl 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
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules 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 μg/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 μg/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 μg/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 μg /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 μg/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 μg/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

μg/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 μL and for Part B is 50

μL, 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°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
59464 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules

limited number of laboratories that will

be qualified to do such analyses, there

should be adequate laboratory capacity

for bromate ion compliance monitoring.

EPA estimates that 250 treatment plants

utilizing ozone will be monitored for

bromate once per month, for a total of

3,000 samples per year.

E. Chlorite

The proposed rule required

monitoring for the chlorite ion for those

systems using chlorine dioxide for

disinfection. The proposed rule

included Method 300.0 (ion

chromatography) for chlorite analysis.

Other methods using amperometric and

potentiometric techniques were

considered, but EPA decided that only

the ion chromatography method (300.0)

would produce results with the

precision needed for compliance

determinations. Several commenters

suggested that EPA permit other

methods for chlorite.

Since the proposed rule, Method

300.1, which uses ion chromatography,

was developed for bromate ion (as

discussed above). Since Method 300.1

can also be used to analyze for chlorite

ion, EPA requests comment on allowing

both Methods 300.0 and 300.1 as

approved methods for the analysis of

chlorite ion.

F. Total Organic Carbon (TOC)

The proposed rule included two

methods for analyzing TOC: Standard

Method 5310 C and 5310 D (APHA

1992). These methods were selected

because they cite a detection limit ≤0.5

mg/L and a precision of ± 0.1 mg/L

TOC. Standard Method 5310 B (18th

edition) was considered, but not

proposed because the method had a

detection limit of 1 mg/L. The proposal

stated that if planned improvements to

the instrumentation in 5310 B were

successful, the next version would be

considered for promulgation.

Improvements were made to method

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 nonhumic 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

μm 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 (UV254), by the

dissolved organic carbon (DOC), and

multiplying by 100:

SUVA = 100 (cm/m) [ UV254 (cm-1)/DOC

(mg/L)]

Two separate analytical methods are

necessary to make this measurement: 1)

UV254 and 2) DOC.

1. UV254. EPA approved Standard

Methods 5910 (APHA 1995) for

measuring UV254 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 UV254.

2. DOC. Standard Methods (19th

Edition-Supplement)(APHA 1996)

defines DOC as the fraction of TOC that

passes through a 0.45 μm-pore-diameter

filter. DOC is measured by performing

an analysis for TOC on the sample

filtrate. Filtration eliminates particulate

organic matter but may contaminate the

sample if carbon-containing compounds

leach from the filter. Standard Methods

5310 B, 5310 C and 5310 D require that

filters be rinsed before use and checked

for their contribution to DOC by

analyzing a filtered blank. Contact with

organic material such as plastic

containers, rubber tubing, etc. must be

kept to a minimum to prevent

contamination. EPA requests comments

on the approval of Standard Methods

5310 B, 5310 C and 5310 D for

measuring DOC for the SUVA

calculation.

EPA is aware of several issues relating

to the measurement of SUVA that are

not addressed in the methods above. In

determining SUVA, DOC and UV254 are

both to be measured from the same

sample filtrate, which is prepared by

filtering a raw water sample through a

pre-washed 0.45 μm 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.ClO2 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
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules 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¥4 risk level for bromate is 5 μg/L, an

MCL of 0.010 mg/L (10 μg/L) was

proposed (because available analytical

detection methods for bromate were

reliable only to the projected practical

quantification limit (PQL) of 10 μg/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 μg/L]) and

whether the PQL for bromate could be

lowered to 5 μg/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.
59466 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules

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

Rule (promulgation)

Surface water PWS Ground water PWS

≥10k <10k ≥10k <10k

DBP 1 (11/98) .................................................................. 5/00 ........................................................... 5/02 5/02 11/03

IESWTR (11/98) ............................................................... 5/00 ........................................................... NA NA NA

LTESWTR (11/00) ............................................................ 5/02 (if required) ........................................ 5/02 NA NA

GWDR (11/00) .................................................................. NA ............................................................. NA (1) (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
59468 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules

not necessary for large and medium

surface systems because compliance

within 18 months is ‘‘practicable’’. To

maintain simultaneous compliance, the

Agency would also have to make the

same practicability determination for

small surface water systems in

complying with the LTESWTR and for

ground water systems serving at least

10,000 in complying with the GWDR. In

addition, the Agency would need to

justify 42 months for small surface

water systems and 60 months for small

ground water systems with disinfection

by making a national determination that

the additional time was required due to

the need for capital improvements at

each of these small systems. EPA also

would need to articulate a rationale for

why States should not be provided the

statutorily specified 24 months to

implement new complex regulatory

provisions before PWSs are required to

comply. Finally, to implement this

approach, the Agency would be

required to modify the timing associated

with the microbial backstop provision

agreed to on July 15, 1997 by the M–

DBP Advisory Committee (since a 18

month schedule would not allow time

after promulgation for medium surface

water systems (10,000–99,999) to collect

HAA data prior to having to determine

whether disinfection benchmarking is

necessary).

EPA requests comment on the issues

outlined above in connection with this

option. In particular, the Agency

requests comment and information to

support a finding that compliance by

specified systems in 18 months is

practicable for some rules, and that

extensions to 42 or 60 months for other

systems are required to allow for capital

improvements.

OPTION 2.—ADD 18 MONTHS TO 1994 PROPOSAL SCHEDULE

Rule (promulgation)

Surface water PWS Ground water PWS

≥10k <10k ≥10k <10k

DBP 1 (11/98) .................................................................. 11/01 ......................................................... 11/03 11/03 5/05

IESWTR (11/98) ............................................................... 11/01 ......................................................... NA NA NA

LTESWTR (11/00) ............................................................ 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 twoyear 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
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules 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

Rule (promulgation)

Surface water PWS Ground water PWS

≥10k <10k ≥10k <10k

DBP 1 (11/98) .................................................................. 11/01 ......................................................... 11/01 11/01 11/01

IESWTR (11/98) ............................................................... 11/01 ......................................................... NA NA NA

LTESWTR (11/00) ............................................................ 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

Rule (promulgation)

Surface water PWS Ground water PWS

≥10k <10k ≥10k <10k

DBP 1 (11/98) .................................................................. 11/01 ......................................................... 11/03 11/03 11/03

IESWTR (11/98) ............................................................... 11/01 ......................................................... NA NA NA

LTESWTR (11/00) ............................................................ 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
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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,
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1Percentages 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.

2Percentages 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.

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 reevaluating 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 1 water

systems nationwide. The American

Waterworks Service Company

(AWWSCo.) data set provided two years

of data (1991 and 1992) for 52 plants,

located primarily in the Northeast and

Midwest.

Using these two data sets and

experience and personal knowledge of

many of these particular plants, the

1997 TWG was able to undertake a

plant-by-plant assessment of the

prospective compliance choices of the

plants likely to have to change treatment

in order to comply with the Advisory

Committee recommendations for the

Stage 1 DBPR. By computing the

percentage of systems forecast to require

the more expensive advanced

treatments, it was possible to see if

results were in the same range as that

projected in the 1994 RIA analysis. This

decision tree analysis is detailed below.

B. Decision Tree Analysis—Compliance

Forecasts

A sub-group of the 1997 TWG

consisting of individuals familiar with

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

μug/L or 48 μg/L, respectively. These

numbers are design targets for

maximum contaminant levels (MCLs) of

80 μg/L and 60 μg/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

Treatment technology to be implemented

1993 stage

1 RIA (percent)

Analysis of

1996 WIDB

data

Analysis of

AWWSCo

1991–1992

data (percent)

Maintain Current Treatment ..................................................................................................................... 28 39.0 22

Chlorine/Chloramine ................................................................................................................................. 3 16.6 28

Enhanced Coagulation + Cl2/NH2Cl ......................................................................................................... 10 19.0 35

Enhanced Coagulation + Cl2 .................................................................................................................... 43 19.0 ....................

Ozone/Chloramine .................................................................................................................................... 5 2.2 7.5

Enhanced Coagulation + O3/NH2Cl ......................................................................................................... 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¥4 risk level

for Giardia.

Since the 1994 proposal, the IESWTR

requirement to achieve a 10¥4 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 2 systems in the 1996

WIDB data set (23.7%) that had either

TTHM ≥64 μg/l or HAA(5) ≥48 μg/l. The

systems were evaluated at a plant-byplant level, incorporating multiple plant

compliance strategies where applicable

and other data, such as that available

from the ICR plant schematics. Results

are tabulated in Table VIII–1. Based on

the case-by-case analysis of this sample,

the TWG predicted that 20 of the 73

systems would require advanced

technologies in order to comply with

the proposed MCLs. This equates to a

decision tree percentage of 6.4% (20/

308) based on WIDB data to 15% (based

on AWWSCo data). The TWG assigned

another 51 systems (16.6%) to a

compliance category consisting of

various combinations of relatively low

cost strategies, such as moving the point

of predisinfection and using

chloramines. Only two of the 73 systems

were projected to install enhanced

coagulation purely for purposes of

meeting the MCLs.

The 1997 TWG did not forecast the

number of systems in the WIDB data set

that would have to install enhanced

coagulation in compliance with the

treatment technique requirements in the

Stage 1 proposal. Because several years

have passed since the negotiated

rulemaking process, some water systems

have probably already moved ahead

with implementation of enhanced

coagulation. Indeed, some systems were

achieving enhanced coagulation

standards even before it was given its

name during the negotiated rulemaking
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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 MDBP 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

μg/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 systemlevel 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)

Treatment technology

Total surface water systemsTotal ground water systems

<10,000 >10,000 <10,000 >10,000

Cl2/NH2Cl .......................................................................................................................... $4.36 $0.69 $9.39 $1.10

Enhanced coagulation ...................................................................................................... 10.48 6.70 0.00 0.00

EC/NH2Cl .......................................................................................................................... 14.84 7.39 0.00 0.00

Oz/NH2Cl .......................................................................................................................... 69.10 8.36 0.00 14.74

EC+Oz/NH2Cl ................................................................................................................... 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

Influent

TOC (mg/L)

% removal

of TOC (%)

TTHM s

(μg/L)

HAA5s

(μg/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.

• 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.

• 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.

• The DBPRAM baseline assumptions

are roughly similar to the 1996 WIDB

data at the medians for TTHMs (46 vs.

40 μg/l) and HAA5 (28 vs 29 μg/l). The

1991 and 1992 AWWSCo. data are

higher for both TTHM (59 and 65 μg/l)
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and HAA5 (42 and 34 μg/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; redefinition 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
Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules 59479

additional pathogen and turbidity

removal.

IX. National Technology Transfer and

Advancement Act

Under section 12(d) of the National

Technology Transfer and Advancement

Act (‘‘NTTAA’’), the Agency is required

to use voluntary consensus standards in

its regulatory activities unless to do so

would be inconsistent with applicable

law or otherwise impractical. Voluntary

consensus standards are technical

standards (e.g., materials specifications,

test methods, sampling procedures,

business practices, etc.) that are

developed or adopted by voluntary

consensus standards bodies. Where

available and potentially applicable

voluntary consensus standards are not

used by EPA, the Act requires the

Agency to provide Congress, through

the Office of Management and Budget,

an explanation of the reasons for not

using such standards.

The analytical methods that are

discussed in this Notice were, with two

exceptions, developed and proposed

prior to the enactment of the NTTAA.

Since EPA is now requesting public

comment on potential changes to the

methods for the Stage 1 DBPR, the

Agency felt it would be appropriate to

also explain the requirements of the

NTTAA and seek comment on these

methods and possible modifications to

these methods in that context as well.

EPA’s process for developing the

analytical test methods in the proposal

and the potential modifications to those

methods is similar to the requirements

of the NTTAA. EPA performed literature

searches to identify analytical methods

from industry, academia, voluntary

consensus standards bodies, and other

parties that could be used to measure

disinfectants, disinfection byproducts,

and other parameters. In addition, EPA’s

development of the methods benefited

from the recommendations of an

Advisory Committee established under

the Federal Advisory Committee Act to

assist the Agency with the Stage 1

DBPR. The Committee made available

additional technical experts who were

well-versed in both existing analytical

methods and new developments in the

field. The results of these efforts formed

the basis for the analytical methods in

the 1994 proposed rule in which EPA

included: six methods for measuring

different disinfection byproducts, of

which five are EPA methods and one is

a voluntary consensus standard; nine

methods for measuring disinfectants, all

of which are voluntary consensus

standards; two voluntary consensus

methods for measuring total organic

carbon (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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71. Parrish, J. M., Austin, E. W., Stevens, D.

K., Kinder, D. H. and R. J. Bull 1996.

Haloacetate-induced oxidative damage to

DNA in the liver of male B6C3F1 mice.

Toxicology 110:103–111.

72. Parry, J. M., Parry, E. M., Bourner, R., et

al. 1996. The detection and evaluation of

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73. Pegram, R. A., Andersen, M. E., Warren,

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1997. Glutathione S-transferase-mediated

mutagenicity of trihalomethanes in

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74. Pereira, M. A. 1996. Carcinogenic activity

of dichloroacetic acid and trichloroacetic

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75. Pereira, M.A. and J.B. Phelps. 1996.

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76. Potter, C.L., L.W. Chang, A.B. DeAngelo

and F.B. Daniel. 1996. Effects of four

trihalomethanes on DNA strand breaks,

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serum testosterone in male F–344 rats.

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77. Randtke, S. J.; Hoehn, R. C.; Knocke, W.

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78. Reif, J. S. et al. 1996. Reproductive and

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104(10):1056–1061.

79. Richard, A.M. and E.M Hunter. 1996.

Quantitative Structure-Activity

Relationships for the Developmental

Toxicity of Haloacetic Acids in

Mammalian Whole Embryo Culture.

Teratology 53:352–360.

80. Roldan-Arjona, T. and C. Pueyo. 1993.

Mutagenic and lethal effects of

halogenated methanes in the Ara test of

Salmonella typhimurium: Quantitative

relationship with chemical reactivity.

Mutagenesis. 8 (2):127–131.

81. Saillenfait, A. M., Langonne, I. and J. P.

Sabate, 1995. Developmental toxicity of

trichloroethylene, tetrachloroethylene

and four of their metabolites in rat whole

embryo culture. Arch Toxicol 70:71–82.

82. Savitz, D. A., Andrews, K. W. and L. M.

Pastore. 1995. Drinking Water and

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83. Shelby, M. D. and K. L. Witt. 1995.

Comparison of results from mouse bone

marrow chromosome aberration and

micronucleus tests. Environmental and

Molecular Mutagenesis. 25(4):302–313.

84. Shorney, H. L. and S. J. Randtke. 1994.

‘‘Enhanced Lime softening for Removal

of Disinfection By-Product Precursors,’’

Proceedings 1994 AWWA Annual

Conference, New York, NY.

85. Shorney, H. L., Randtke, S. J., Hargette,

P. H., Mann, P. D., Hoehn, R.C., Knocke,

W. R., Dietrich, A. M. and B. W. Long.

‘‘The Influence of Raw Water Quality on

Enhanced Coagulation and Softening for

the Removal of NOM and DBP Formation

Potential’’, Proceedings 1996 AWWA

Annual Conference, Toronto, Ontario,

Canada.

86. Singer, P. C., Harrington, G. W.,

Thompson, J. D. and M. C. White. 1995.

Enhanced Coagulation and Enhanced

Softening for the Removal of Disinfection

By-Product Precursors: An Evaluation.

Report prepared for the AWWA

Government Affairs Office, Washington,

DC, by the Dept. of Environmental

Sciences and Engineering, UNC, Chapel

Hill, NC.

87. Singer, P. C., Harrington, G. W.,

Thompson, J. and M. White. ‘‘Enhanced

Coagulation and Enhanced Softening for

the Removal of Disinfection By-Product

Precursors: An Evaluation,’’ Report to

AWWA Disinfectants/Disinfection ByProducts Technical Advisory Workgroup

of the Water Utility Council, December

1996.

88. Sofuni, T., Honma, M., Hayashi, M.,

Shimada, H., Tanaka, N., Wakuri, S.,

Awogi, T., Yamamoto, K. I., Nishi, Y.

and M. Nakadate. 1996. Detection of in

vitro clastogens and spindle poisons by

the mouse lymphoma assay using the

microwell method: interim report of an

international collaborative study.

Mutagenesis 11(4):349–55.

89. Solarik, G., V.A. Hatcher, R.S. Isabel, J.F.

Stile, and R.S. Summers. 1997.

Prechlorination and DBP Formation: The

Impact of Chlorination Point and

Enhanced Coagulation, Proceedings,

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Conference, Denver, CO.

90. Sprankle, C.S., J.L. Larson, S.M.

Goldsworthy and B.E.Butterworth. 1996.

Levels of myc, fos, Ha-ras, met and

hepatocyte growth factor mRNA during

regenerative cell proliferation in female

mouse liver and male rat kidney after a

cytotoxic dose of chloroform. Cancer Lett

101(1):97–106.

91. Summers, R.S., S.M. Hooper, H.M.

Shukairy, G. Solarik, and D.M. Owen.

1996. Assessing DBP Yields: Uniform

Formation Conditions, Journal AWWA,

88:6:80.

92. Summers, R.S., G. Solarik, V.A. Hatcher,

R.S. Isabel, and J.F. Stile. 1997.

Analyzing the Impacts of Predisinfection

Through Jar Testing, Proceedings,

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Conference, Denver, CO.

93. Tao, L., Li, K., Kramer, P.M., et al. 1996.

Loss of heterozygosity on chromosome 6

in dichloroacetic acid and trichloroacetic

acid-induced liver tumors in female

B6C3F1 mice. Cancer Lett 108:257–261.
59482 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules

94. Templin, M.V., Jamison, K.C., Wolf, D.C.,

Morgan, K.T. and B.E. Butterworth.

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95. Templin, M.V., Larson, J.L., Butterworth,

B.E., Jamison, K.C., Leininger, J.R., Mery,

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Wolf. 1996b. A 90-day chloroform

inhalation study in F-344 rats: Profile of

toxicity and relevance to cancer studies.

Fund. Appl. Toxicol. 32:109–125.

96. Testai, E., Di Marzio, S., Di Domenico, A.,

Piccardi, A. and L. Vittozzi. 1995. An in

vitro investigation of the reductive

metabolism of chloroform. Arch.

Toxicol. 70(2):83–8.

97. Thornton-Manning, J.R., J.C. Seely and

R.A. Pegram. 1994. Toxicity of

bromodichloromethane in female rats

and mice after repeated oral dosing.

Toxicology 94(1–3):3–18.

98. Thurman, E.M., and R.L. Malcolm. 1981.

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99. Tseng, T. and M. Edwards. 1997.

Considerations in Optimizing

Coagulation. Proc. 1996 AWWA Water

Qual. Technol. Conf., Boston, Mass.

100. U.S. EPA. 1979. National Interim

Primary Drinking Water Regulations;

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Water. Fed. Reg., 44:231:68624.

(November 29, 1979.)

101. U.S. EPA. 1989a. National Primary

Drinking Water Regulations; Filtration,

Disinfection; Turbidity, Giardia lamblia,

Viruses, Legionella, and Heterotrophic

Bacteria; Final Rule. Part II. Fed. Reg.,

54:124:27486. (June 29, 1989)

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Drinking Water Regulations; Total

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105. U.S.EPA. 1992c. Technologies and Costs

for Control of Disinfectant By-Products.

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106. U.S. EPA. 1993a. Methods for the

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Environmental Samples. EPA–600/R–93/

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107. U.S. EPA/ILSI. 1993b. A Review of

Evidence on Reproductive and

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Washington: U.S. Environmental

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108. U.S. EPA. 1994a. Workshop Report and

Recommendations for Conducting

Epidemiologic Research on Cancer and

Exposure to Chlorinated Drinking Water.

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109. U.S. EPA. 1994b. National Primary

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110. U.S. EPA. 1994c. National Primary

Drinking Water Regulations; Enhanced

Surface Water Treatment Requirements;

Proposed Rule. Fed. Reg., 59:145:38832.

(July 29, 1994).

111. U.S. EPA. 1994d. National Primary

Drinking Water Regulations; Monitoring

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Supplies; Proposed Rule. Fed. Reg.,

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Determination of Organic Compounds in

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for Carcinogen Risk Assessment.

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114. U.S. EPA. 1996b. National Primary

Drinking Water Regulations: Monitoring

Requirements for Public Drinking Water

Supplies; Final Rule. Fed. Reg.,

61:94:24354. (May 14, 1996)

115. U.S. EPA. 1997a. Occurrence and

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Drinking Water Supplies. Preliminary

Draft. U.S. Environmental Protection

Agency.

116. U.S. EPA. 1997b. Summaries of New

Health Effects Data. Office of Science

and Technology, Office of Water.

October 1997.

117. U.S. EPA. 1997c. Method 300.1,

Determination of Inorganic Anions in

Drinking Water by Ion Chromatography.

Revision 1.0. USEPA National Exposure

Research Laboratory, Cincinnati, OH.

118. U.S. EPA. 1997d. Guidance Manual for

Enhanced Coagulation and Enhanced

Precipitative Softening. Preliminary

Draft. U.S. Environmental Protection

Agency.

119. Vena, J.E. et al. 1993. Drinking Water,

Fluid Intake, and Bladder Cancer in

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120. Vorce, R.L. and J.I. Goodman. 1991.

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chemically induced and spontaneous

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Environ Health 34(3):367–84.

121. White, M.C., Thompson, J.D.,

Harrington, G.W., and P.S. Singer. 1997.

Evaluating Criteria for Enhanced

Coagulation Compliance. AWWA,

89:5:64.

122. Wolfe, G., and Kaiser, L. 1996. Final

Report. Sodium Bromate: Short Term

Reproductive and Developmental

Toxicity Study when administered to

sprague-Dawley Rats in the Drinking

water. Study No. NTP–REST. 94007.

NTP/NIEHS No. NOI–ES–15323.

123. Xie, Yuefeng. 1995. Effects of Sodium

Chloride on DBP Analytical Results,

Extended Abstract, Division of

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Chemical Society Annual Conference,

Chicago, IL, Aug. 21–26, 1995.

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

Alkalinity (mg/l)

TOC (mg/

l) ......... 0¥<60 60¥<120 ≥120

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
59484 Federal Register / Vol. 62, No. 212 / Monday, November 3, 1997 / Proposed Rules

basis. Exceptions reporting shall include the

following: (1) any individual filter with a

turbidity level greater than 1.0 NTU based on

2 consecutive measurements fifteen minutes

apart; and (2) any individual filter with a

turbidity level greater than 0.5 NTU at the

end of the first 4 hours of filter operation

based on 2 consecutive measurements fifteen

minutes apart. A filter profile will be

produced if no obvious reason for the

abnormal filter performance can be

identified.

If an individual filter has turbidity levels

greater than 1.0 NTU based on 2 consecutive

measurements fifteen minutes apart at any

time in each of 3 consecutive months, the

system shall conduct a self-assessment of the

filter utilizing as guidance relevant portions

of guidance issued by the Environmental

Protection Agency for Comprehensive

Performance Evaluation (CPE). If an

individual filter has turbidity levels greater

than 2.0 NTU based on 2 consecutive

measurements fifteen minutes apart at any

time in each of two consecutive months, the

system will arrange for the conduct of a CPE

by the State or a third party approved by the

State.

State Authority. States must have rules or

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:

• Data and research needs and limitations

(e.g. occurrence, treatment, viability, active

disease surveillance, etc.);

• Technology and methods capabilities

and limitations;

• Removal and inactivation effectiveness;

• Risk tradeoffs including risks of

significant shifts in disinfection practices;

• Cost considerations consistent with the

SDWA;

• Reliability and redundancy of systems;

• Consistency with the requirements of the

Act.

2.9 Sanitary Surveys

Sanitary surveys operate as an important

preventive tool to identify water system

deficiencies that could pose a risk to public

health. EPA and ASDWA have issued a joint

guidance dated 12/21/95 on the key

components of an effective sanitary survey.

The following provisions concerning sanitary

surveys should be included.

I. Definition

(A) A sanitary survey is an onsite review

of the water source (identifying sources of

contamination using results of source water

assessments where available), facilities,

equipment, operation, maintenance, and

monitoring compliance of a public water

system to evaluate the adequacy of the

system, its sources and operations and the

distribution of safe drinking water.

(B) Components of a sanitary survey may

be completed as part of a staged or phased

state review process within the established

frequency interval set forth below.

(C) A sanitary survey must address each of

the eight elements outlined in the December

1995 EPA/STATE Guidance on Sanitary

Surveys.

II. Frequency

(A) Conduct sanitary surveys for all surface

water systems (including groundwater under

the influence) no less frequently than every

three years for community systems except as

provided below and no less frequently than

every five years for noncommunity systems.

—May ‘‘grandfather’’sanitary surveys

conducted after December 1995, if they

address the eight sanitary survey

components outlined above.

(B) For community systems determined by

the State to have outstanding performance

based on prior sanitary surveys, successive

sanitary surveys may be conducted no less

than every five years.

III. Follow Up

(A) Systems must respond to deficiencies

outlined in a sanitary survey report within at

least 45 days, indicating how and on what

schedule the system will address significant

deficiencies noted in the survey.

(B) States must have the appropriate rules

or other authority to assure that facilities take

the steps necessary to address significant

deficiencies identified in the survey report

that are within the control of the PWS and

its governing body.

Agreed to by:

lllllllllllllllllllll

Name, Organization

lllllllllllllllllllll

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