National Primary Drinking Water Regulations; Radon-222

Note: EPA no longer updates this information, but it may be useful as a reference or resource.

[Federal Register: November 2, 1999 (Volume 64, Number 211)]
[Proposed Rules]
[Page 59245-59294]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr02no99-35]

[[Page 59245]]

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Part II

Environmental Protection Agency

_______________________________________________________________________

40 CFR Parts 141 and 142

National Primary Drinking Water Regulations; Radon-222; Proposed Rule

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 141 and 142

[WH-FRL-6462-8]
RIN 2040-AA94

National Primary Drinking Water Regulations; Radon-222

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of proposed rulemaking.

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SUMMARY: In this action, the Environmental Protection Agency (EPA) is
proposing a multimedia approach to reducing radon risks in indoor air
(where the problem is greatest), while protecting public health from
the highest levels of radon in drinking water. Most radon enters indoor
air from soil under homes and other buildings. Only approximately 1-2
percent comes from drinking water. The Agency is proposing a Maximum
Contaminant Level Goal (MCLG) and National Primary Drinking Water
Regulations (NPDWR) for radon-222 in public water supplies. Under the
framework set forth in the 1996 amendments to the SDWA, EPA is also
proposing an alternative maximum contaminant level (AMCL) and
requirements for multimedia mitigation (MMM) programs to address radon
in indoor air. Public water systems (PWS) are defined in the Safe
Drinking Water Act (SDWA). This proposed rule applies to community
water systems (CWS), a subset of PWSs. Under the proposed rule, CWSs
may comply with the AMCL if they are in States that develop an EPA-
approved MMM program or, in the absence of a State program, develop a
State-approved CWS MMM program. This approach is intended to encourage
States, Tribes, and CWSs to reduce the health risk of radon in the most
cost-effective way. The Agency is also proposing a maximum contaminant
level (MCL) for radon-222, to apply to CWSs in non-MMM States that
choose not to implement a CWS MMM program. The proposal also includes
monitoring, reporting, public notification, and consumer confidence
report requirements for radon-222 in drinking water.

DATES: EPA must receive public comments, in writing, on the proposed
regulations by January 3, 2000.

ADDRESSES: You may send written comments to the Radon-222, W-99-08
Comments Clerk, Water Docket (MC-4101); U.S. Environmental Protection
Agency; 401 M Street, SW., Washington, DC 20460. Comments may be hand-
delivered to the Water Docket, U.S. Environmental Protection Agency;
401 M Street, SW., East Tower Basement, Washington, DC 20460. Comments
may be submitted electronically to owdocket@epamail.epa.gov. Electronic
comments must be submitted as an ASCII, WP6.1, or WP8 file avoiding the
use of special characters and any form of encryption. Electronic
comments must be identified by the docket number W-99-08. Comments and
data will also be accepted on disks in WP6.1, WP8, or ASCII format.
Electronic comments on this action may be filed online at many Federal
Depository libraries.
Please submit a copy of any references cited in your comments.
Facsimiles (faxes) cannot be accepted. EPA would appreciate one
original and three copies of your comments and enclosures (including
any references). Commenters who would like EPA to acknowledge receipt
of their comments should include a self-addressed, stamped envelope.
The proposed rule and supporting documents, including public
comments, are available for review in the Water Docket at the address
listed previously. The Docket also has several of the key supporting
documents electronically available as PDF files. For information on how
to access Docket materials, please call (202) 260-3027 between 9 a.m.
and 3:30 p.m. Eastern Time, Monday through Friday.

FOR FURTHER INFORMATION CONTACT: For general information on radon in
drinking water, contact the Safe Drinking Water Hotline, phone (800)
426-4791. The Safe Drinking Water Hotline is open Monday through
Friday, excluding Federal holidays, from 9 a.m. to 5:30 p.m. Eastern
Time. For technical inquiries regarding the proposed regulations,
contact Sylvia Malm, Office of Ground Water and Drinking Water, U.S.
Environmental Protection Agency (mailcode 4607), 401 M Street, SW,
Washington DC, 20460. Phone: (202) 260-0417. E-mail:
malm.sylvia@epa.gov. For inquiries regarding the proposed multimedia
mitigation program, contact Anita Schmidt, Office of Radiation and
Indoor Air, U.S. Environmental Protection Agency, (mailcode 6609J), 401
M Street, S.W, Washington, DC, 20460. Phone: (202) 564-9452. E-mail:
schmidt.anita@epa.gov. For general information on radon in indoor air,
contact the Radon Hotline at 1-800-SOS-RADON (1-800-767-7236).

SUPPLEMENTARY INFORMATION:

Potentially Regulated Entities

Potentially regulated entities include community water systems
using ground water or mixed ground and surface water.
The following table lists potentially regulated entities. This
table is not intended to be exhaustive, but rather provides a guide for
readers regarding entities likely to be regulated by this action. This
table lists the types of entities that EPA is now aware of that could
potentially be regulated by this action. Other entities not listed in
the table could also be regulated. To determine whether your
organization is affected by this action, you should carefully examine
the proposed applicability criteria in section 40 CFR parts
141.20(b)(1) and Section IV of the preamble. If you have questions
regarding the applicability of this action to a particular entity,
consult Sylvia Malm who is listed in the preceding FOR FURTHER
INFORMATION CONTACT section.

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Examples of potentially
Category regulated entities
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Industry.................................. Privately owned/operated
community water supply
systems using ground water
or mixed ground water and
surface water.
State, Tribal, and Local Government....... State, Tribal, or local
government-owned/operated
water supply systems using
ground water or mixed
ground water and surface
water.
Federal Government........................ Federally owned/operated
community water supply
systems using ground water
or mixed ground water and
surface water.
------------------------------------------------------------------------

Abbreviations Used in This Proposal

AMCL: Alternative Maximum Contaminant Level
BAT: Best Available Technology
BEIR: Committee on the Biological Effects of Ionizing Radiation. The
Committee on Health Risks of Exposure on Radon that conducted the
National Research Council Biological Effects of Ionizing Radiation
(BEIR) VI Study (NAS 1999a). The committee is formed by the Radiation
Effect Research/Commission on Life Sciences/National Research Council/
National Academy of Sciences.
CFR: Code of Federal Regulations
CWS: Community Water System
EF: Equilibrium Factor
EPA: U.S. Environmental Protection Agency
FR: Federal Register
GAC: Granular Activated Carbon

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HRRCA: Health Risk Reduction and Cost Analysis
IOC: Inorganic Contaminant
LSC: Liquid Scintillation Counting
MCL: Maximum Contaminant Level
MCLG: Maximum Contaminant Level Goal
MMM: Multimedia Mitigation
NAS: National Academy of Sciences
NAS Radon in Drinking Water Committee: The Committee on Risk Assessment
of Exposure to Radon of the Drinking Water that conducted the National
Research Council Risk Assessment of Radon in Drinking Water Study (NAS
1999b). The committee is formed by the Board of Radiation Effect
Research of the Commission on Life Sciences of the National Research
Council, National Academy of Sciences.
NELAC: National Environmental Laboratory Accreditation Conference
NIST: National Institute of Standards and Technology
NIRS: National Inorganics and Radionuclides Survey
NPDWR: National Primary Drinking Water Regulation
NPRM: Notice of Proposed Rulemaking
NTNC: Non-Transient, Non-Community
OGWDW: Office of Ground Water and Drinking Water
OMB: Office of Management and Budget
PBMS: Performance-Based Measurement System
PE: Performance Evaluation
PT: Proficiency Testing
POE: Point-of-Entry
POU: Point-of-Use
PRA: Paperwork Reduction Act
PWS: Public Water System
pCi/L: Picocuries per Liter
RFA: Regulatory Flexibility Act
SAB: Science Advisory Board
SBA: Small Business Administration
SBO: Small Business Ombudsman
SBREFA: Small Business Regulatory Enforcement and Fairness Act
SDWA: Safe Drinking Water Act
SDWIS: Safe Drinking Water Information System
SIRG: State Indoor Radon Grant
SSCT: Small Systems Compliance Technology
SSVT: Small Systems Variance Technology
SMF: Standardized Monitoring Framework
UMRA: Unfunded Mandates Reform Act
URTH: Unreasonable Risks to Health
WL: Working Level
WLM: Working Level Month

Table of Contents

I. Summary: What Does Today's Proposed Rulemaking Mean for My Water
System?
A. Why is EPA Proposing to Regulate Radon in Drinking Water?
B. What is Radon?
C. What are the Health Concerns from Radon in Air and Water?
D. Does this Regulation Apply to My Water System?
E. How Will this Regulation Protect Public Health?
F. How Will the Multimedia Mitigation (MMM) Program Work?
G. What are the Proposed Limits for Radon in Drinking Water?
H. What is the Proposed Best Available Technology (BAT) for
Treating Radon in Drinking Water?
I. What Analytical Methods are Recommended?
J. Where and How Often Must I Test My Water for Radon?
K. May I Use Point-of-Use (POU) Devices, Point-of-Entry (POE)
Devices, or Bottled Water to Comply with this Regulation?
L. May I Get More Time or Use a Cheaper Treatment? Variances and
Exemptions
M. What are State Primacy, Record Keeping, and Reporting
Requirements?
N. How are Tribes Treated in this Proposal?

Statutory Requirements and Regulatory History

II. What Does the Safe Drinking Water Act Require the EPA to Do When
Regulating Radon in Drinking Water?
A. Withdraw the 1991 Proposed Regulation for Radon
B. Arrange for a National Academy of Sciences Risk Assessment.
C. Set an MCLG, MCL, and BAT for Radon-222
D. Set an Alternative MCL (AMCL) and Develop Multimedia
Mitigation (MMM) Program Plan Criteria
E. Evaluate Multimedia Mitigation Programs Every Five Years
III. What Actions Has EPA Taken on Radon in Drinking Water Prior to
This Proposal?
A. Regulatory Actions Prior to 1991
B. The 1991 NPRM
C. 1994 Report to Congress: Multimedia Risk and Cost Assessment
of Radon
D. 1997 Withdrawal of the 1991 NPRM for Radon-222
E. 1998 SBREFA Small Business Advocacy Review Panel for Radon
F. 1999 HRRCA for Radon in Drinking Water

Requirements

IV. To Which Water Systems Does this Regulation Apply?
V. What is the Proposed Maximum Contaminant Level Goal (MCLG) for
Radon?
A. Approach to Setting the MCLG
B. MCLG for Radon in Drinking Water
VI. What Must a State or Community Water System Have In Its
Multimedia Mitigation Program Plan?
A. What are the Criteria?
B. Why Will MMM Programs Get Risk Reduction Equal or Greater
Than Compliance with the MCL?
C. Implementation of an MMM Program in Non-Primacy States
D. Implementation of the MMM Program in Indian Country
E. CWS Role in State MMM Programs
F. Local CWS MMM Programs in Non-MMM States and State Role in
Approval of CWS MMM Program Plans
G. CWS Role in Communicating to Customers
H. How Did EPA Develop These Criteria?
I. Background on the Existing EPA and State Indoor Radon
Programs
VII. What are the Requirements for Addressing Radon in Water and
Radon in Air? MCL, AMCL and MMM
A. Requirements for Small Systems Serving 10,000 People or Less
B. Requirements for Large Systems Serving More Than 10,000
People
C. State Role in Approval of CWS MMM Program Plans
D. Background on Selection of MCL and AMCL
E. Compliance Dates
VIII. What are the Requirements for Testing for and Treating Radon
in Drinking Water?
A. Best Available Technologies (BATs), Small Systems Compliance
Technologies (SSCTs), and Associated Costs
B. Analytical Methods
C. Laboratory Approval and Certification
D. Performance-Based Measurement System (PBMS)
E. Proposed Monitoring and Compliance Requirements for Radon
IX. State Implementation
A. Special State Primacy Requirements
B. State Record Keeping Requirements
C. State Reporting Requirements
D. Variances and Exemptions
E. Withdrawing Approval of a State MMM Program
X. What Do I Need to Tell My Customers? Public Information
Requirements
A. Public Notification
B. Consumer Confidence Report

Risk Assessment and Occurrence

XI. What is EPA's Estimate of the Levels of Radon in Drinking Water?
A. General Patterns of Radon Occurrence
B. Past Studies of Radon Levels in Drinking Water
C. EPA's Most Recent Studies of Radon Levels in Ground Water
D. Populations Exposed to Radon in Drinking Water
XII. What Are the Risks of Radon in Drinking Water and Air?
A. Basis for Health Concern
B. Previous EPA Risk Assessment of Radon in Drinking Water
C. NAS Risk Assessment of Radon in Drinking Water
D. Estimated Individual and Population Risks
E. Assessment by National Academy of Sciences: Multimedia
Approach to Risk Reduction

Economics and Impacts Analysis

XIII. What is the EPA's Estimate of National Economic Impacts and
Benefits?
A. Safe Drinking Water Act (SDWA) Requirements for the HRRCA
B. Regulatory Impact Analysis and Revised Health Risk Reduction
and Cost Analysis (HRRCA) for Radon

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C. Baseline Analysis
D. Benefits Analysis
E. Cost Analysis
F. Economic Impact Analysis
G. Weighing the Benefits and Costs
H. Response to Significant Public Comments on the February 1999
HRRCA
XIV. Administrative Requirements
A. Executive Order 12866: Regulatory Planning and Review
B. Regulatory Flexibility Act (RFA)
C. Unfunded Mandates Reform Act (UMRA)
D. Paperwork Reduction Act (PRA)
E. National Technology Transfer and Advancement Act (NTTAA)
F. Executive Order 12898: Environmental Justice
G. Executive Order 13045: Protection of Children from
Environmental Health Risks and Safety Risks
H. Executive Order on Federalism
I. Executive Order 13084: Consultation and Coordination with
Indian Tribal Governments
J. Request for Comments on Use of Plain Language

Stakeholder Involvement

XV. How has the EPA Provided Information to Stakeholders in
Development of this NPRM?
A. Office of Ground Water and Drinking Water Website
B. Public Meetings
C. Small Entity Outreach
D. Environmental Justice Initiatives
E. AWWA Radon Technical Work Group

Background

XVI. How Does EPA Develop Regulations to Protect Drinking Water?
A. Setting Maximum Contaminant Level Goal and Maximum
Contaminant Level
B. Identifying Best Available Treatment Technology
C. Identifying Affordable Treatment Technologies for Small
Systems
D. Requirements for Monitoring, Quality Control, and Record
Keeping
E. Requirements for Water Systems to Notify Customers of Test
Results if Not in Compliance
F. Approval of State Drinking Water Programs to Enforce Federal
Regulations
XVII. Important Technical Terms
XVIII. References

Appendix I to the Preamble: What are the Major Public Comments on the
1991 NPRM and How has the EPA Addressed Them in this Proposal?

A. General Issues
B. Statutory Authority and Requirements
C. Radon Occurrence
D. Radon Exposure and Health Effects
E. Maximum Contaminant Level
F. Analytical Methods
G. Treatment Technologies and Cost
H. Compliance Monitoring

I. Summary: What Does Today's Proposed Rulemaking Mean for My Water
System?

A. Why Is EPA Proposing To Regulate Radon in Drinking Water?

The proposed National Primary Drinking Water Regulation (NPDWR) for
radon in drinking water is based on a multimedia approach designed to
achieve greater risk reduction by addressing radon risks in indoor air,
with public water systems providing protection from the highest levels
of radon in their ground water supplies. The framework for this
proposal is set out in the Safe Drinking Water Act as amended in 1996
(SDWA), which provides for a multimedia approach for addressing the
public health risks from radon in drinking water and radon in indoor
air from soil. This statutory-based framework reflects the
characteristics uniquely specific to radon among drinking water
contaminants: that the relative cost-effectiveness of reducing risk
from exposure to this contaminant is substantially greater for a non-
drinking water source of exposure--indoor air--than it is from drinking
water. Accordingly, SDWA directs the Environmental Protection Agency
(EPA) to promulgate a maximum contaminant level (MCL) for radon in
drinking water, but also to make available a higher alternative maximum
contaminant level (AMCL) accompanied by a multimedia mitigation (MMM)
program to address radon risks in indoor air. Further, in setting the
MCL, EPA is to take into account the costs and benefits of programs
that control radon in indoor air (SDWA 1412(b)(13)(E)).

B. What Is Radon?

Radon's Physical Properties
Throughout this preamble, ``radon'' refers to the specific isotope
radon-222. Radon is a naturally occurring gas formed from the
radioactive decay of uranium-238. Low concentrations of uranium and its
other decay products, specifically radium-226, occur widely in the
earth's crust, and thus radon is continually being generated, even in
soils in which there is no man-made radioactive contamination. Radon is
colorless, odorless, tasteless, chemically inert, and radioactive. A
portion of the radon released through radioactive decay moves through
air or water-filled pores in the soil to the soil surface and enters
the air, while some remains below the surface and dissolves in ground
water (water that collects and flows under the ground's surface).
Because radon is a gas, when water that contains radon is exposed
to the air, the radon will tend to be released into the air. Therefore,
radon is usually present in only low amounts in rivers and lakes. If
ground water is supplied to a house, radon in the water will tend to be
released into the air of the house via various water uses. Thus
presence of radon in drinking water supplies leads to exposure via both
oral route (ingesting water containing radon) and inhalation route
(breathing air containing both radon and radon decay products released
from water used in the house such as for cooking and washing).
Radon itself also decays, emitting ionizing radiation in the form
of alpha particles, and transforms into decay products, or ``progeny''
radioisotopes. It has a half-life of about four days and decays into
short-lived progeny. Unlike radon, the progeny are not gases, and can
easily attach to and be transported by dust and other particles in air.
The decay of progeny continues until stable, non-radioactive progeny
are formed. At each step in the decay process, radiation is released.

C. What Are the Health Concerns From Radon in Air and Water?

National and international scientific organizations have concluded
that radon causes lung cancer in humans. The primary risk is lung
cancer from radon entering indoor air from soil under homes. Tap water
is a smaller source of radon in air; however, breathing radon released
to air from household water uses also increases the risk of lung
cancer, and consumption of drinking water containing radon presents a
smaller risk of internal organ cancers, primarily stomach cancer.
In most cases, radon in soil under homes is the biggest source of
exposure and radon from tap water will be a small source of radon in
indoor air.
The U.S. Surgeon General has warned that indoor radon (from soil)
is the second leading cause of lung cancer (USEPA 1988b). The National
Academy of Sciences (NAS 1999a) estimates that radon from soil causes
about 15,000 to 22,000 (using two different approaches) lung cancer
deaths each year in the U.S. If you smoke and your home has high indoor
radon levels, your risk of lung cancer is especially high. EPA and the
U.S. Surgeon General recommend testing all homes below the third floor.
The NAS report mandated by the 1996 SDWA identifies the same unit
risk associated with radon in drinking water compared with previous EPA
analyses. Based on the NAS risk assessment and an updated EPA

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occurrence analysis, the Agency estimates that uncontrolled levels of
radon in public drinking water supplies cause 168 fatal cancers each
year in the U.S. However, radon in domestic drinking water generally
contributes a very small part (about 1-2 percent) of total radon
exposure from indoor air. The NAS estimated that about 89 percent of
the fatal cancers caused by radon in drinking water were due to lung
cancer from inhalation of radon released to indoor air, and about 11
percent were due to stomach cancer from consuming water containing
radon (NAS 1999b).

D. Does This Regulation Apply to My Water System?

The regulation for radon in drinking water and the multimedia
approach proposed in this action would apply to all community public
water systems (CWSs) that use ground water or mixed ground and surface
water. The proposed regulation would not apply to non-transient non-
community (NTNC) public water supplies, nor to transient public water
supplies.

E. How Will This Regulation Protect Public Health?

Given the much greater potential for risk reduction in indoor air
and years of experience with radon mitigation programs, EPA expects
that greater overall risk reduction will result from this proposal than
from an approach which solely addresses radon in public drinking water
supplies. The proposed regulation for radon in drinking water is
intended to promote a more cost-effective multimedia approach to reduce
radon risks, particularly for small systems with limited resources, and
to reduce the highest levels of radon in drinking water. This
determination to have a strong and effective multimedia radon program
to address radon in indoor air is consistent with the SDWA framework
for multimedia radon programs and the SDWA expectation that EPA would
give significant weight to the risk findings of the NAS report, which
confirm the health risks of radon in drinking water, and the much
greater risks from radon in indoor air arising from soil under homes.

F. How Will the Multimedia Mitigation (MMM) Program Work?

The multimedia mitigation (MMM) program is modeled on the National
Indoor Radon Program implemented by EPA, States and others. That
program has achieved substantial risk reduction through voluntary
public action since the release of the original ``A Citizen's Guide to
Radon'' in 1986 (USEPA 1986, 1992b) and the U.S. Surgeon General's
recommendation in 1988 that all homes be tested and elevated levels be
reduced. The program has been successful in achieving indoor radon risk
reduction through a variety of program strategies, which form the basis
for EPA's proposed multimedia mitigation program plan criteria. Based
on the estimated number of existing homes fixed and the number of new
homes built radon-resistant since the national program began in 1986,
EPA estimates that under existing Federal and State indoor radon
programs, a total of more than 2,500 lives will be saved through indoor
radon risk reduction efforts expected to take place through the year
2000. Every year the rate of lives saved increases as more existing
houses with elevated radon levels are fixed and as more new houses are
built radon-resistant. For the year 2000, EPA estimates that the rate
of radon-related lung cancer deaths that will be avoided from
mitigation of existing homes and from homes built radon-resistant (in
high radon areas) will be about 350 lives saved per year (USEPA 1999i).
The MMM/AMCL approach is intended to provide a more cost-effective
alternative to achieve radon risk reduction, by allowing States (or
community water systems) to address radon in indoor air from the soil
source, while reducing the highest levels of radon in drinking water.
It is EPA's expectation that most States will develop State-wide
multimedia mitigation programs as the most cost-effective approach.
Most of the States currently have indoor radon programs that are
addressing radon risk from soil, and can be used as the foundation for
development of MMM program plans. EPA expects that State indoor radon
programs will implement MMM programs under agreements with the State
drinking water programs. The regulatory expectation of community water
systems serving 10,000 persons or less is that they meet the
alternative maximum contaminant level (AMCL) and be associated with an
approved MMM program plan--either developed by the State and approved
by EPA or developed by the CWS and approved by the State. Tribal CWS
MMM programs, as well as those in States and Territories that do not
have drinking water primacy, will be approved by EPA. The same general
criteria for State MMM program plans would apply to CWSs in developing
local MMM programs in States that do not have such a program, albeit
with a local perspective on such criteria and commensurate with the
unique attributes of small CWSs. EPA expects that MMM program
strategies for CWSs will be less comprehensive than those of State MMM
programs, and will need to reflect the local character of the community
served by the CWS. Strong public participation in the development of
the CWS MMM program plans will help to ensure this, as well as
community support for the MMM program. Figures I.1 and I.2 provide a
conceptual model for the MCL, AMCL, and MMM programs for small and
large systems.

BILLING CODE 6560-50-P

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[GRAPHIC] [TIFF OMITTED] TP02NO99.001

BILLING CODE 6560-50-C

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To meet the requirements of SDWA, the risk reduction benefits
expected to be achieved by MMM programs are to be equal to or greater
than risk reduction benefits that would be achieved by CWSs complying
with the MCL. Under SDWA, this means that if all States implemented MMM
programs they would be expected to result in about 62 cancer deaths
averted annually, equal to what would be achieved with universal
compliance with the MCL at 300 pCi/L. Unlike health risk reduction
benefits gained through water treatment, which remain constant from one
year to the next, the rate of health benefits from reducing indoor
radon is cumulative; that is, it steadily increases every year with
every additional existing home that is mitigated and with every new
home built radon-resistant. Therefore, MMM programs will use and build
on the indoor radon program framework to achieve ``equal or greater''
risk reduction, rather than focusing efforts on precisely quantifying
``equivalency'' to the much more limited risk reduction expected to
occur if community water systems complied with the MCL.

G. What Are the Proposed Limits for Radon in Drinking Water?

The proposed regulation provides that States may adopt State-wide
MMM programs and the alternative maximum contaminant level (AMCL) of
4000 pCi/L. This is the most effective approach for radon risk
reduction and the one EPA expects the majority of States to adopt. If a
State has an EPA-approved MMM program plan, CWSs in that State may
comply with the AMCL. In the absence of an approved State MMM program
plan the regulatory expectation for small CWSs (those serving 10,000 or
fewer) is that they comply with a level of 4000 pCi/L in drinking
water, and develop and implement a State-approved local MMM program
plan to reduce indoor radon risks arising from soil and rock under
homes and buildings. Small CWSs may also choose to comply with the MCL
of 300 pCi/L (and not develop a local MMM program.)
The AMCL/MMM approach is EPA's regulatory expectation for small
CWSs because an MMM program and compliance with the AMCL is a much more
cost-effective way to reduce radon risk than compliance with the
maximum contaminant level (MCL) of 300 pCi/L. (While EPA believes that
the MMM approach is preferable for small systems in a non-MMM State,
small CWSs may, at their discretion, choose the option of meeting the
MCL instead of developing a local MMM program). Large CWSs (serving a
population of more than 10,000) must either comply with the proposed
MCL or comply with the AMCL and implement a State-approved CWS MMM
program plan (in the absence of an approved State MMM program plan).
If a State has an approved MMM program plan, the standard for radon
in drinking water that the State would adopt in order to obtain primacy
would be 4000 pCi/L.
Under the proposed requirements, an MMM program plan must address
four criteria:

1. Public involvement in development of the MMM program plan
2. Quantitative goals for existing homes fixed and new homes built
radon-resistant
3. Strategies for achieving goals
4. Plan to track and report results

CWSs must monitor for radon in drinking water according to the
requirements described in Section VIII of this preamble, and report
their results to the State. If the State determines that the radon
level in a CWS is below 300 pCi/L, the system need only continue to
meet monitoring requirements and is not covered by the requirements
described in Section VI of this preamble, regarding MMM programs.

H. What Is the Proposed Best Available Technology (BAT) for Treating
Radon in Drinking Water?

Proposed BAT for Radon Under Section 1412 of the SDWA
High-performance aeration, as described in Section VIII.A of this
preamble, is the BAT for all systems. For systems serving 10,000
persons or fewer, the BAT is high-performance aeration and the Small
Systems Compliance Technologies, as described in Section VIII.A.
Proposed BAT for Radon Under Section 1415 of the SDWA
BAT for purposes of variances is the same as BAT under Section 1412
of the Act.

I. What Analytical Methods Are Recommended?

EPA is proposing Liquid Scintillation Counting (Standard Method
7500-Rn) and de-emanation (``Lucas Cell'') as the approved methods. The
Liquid Scintillation Counting method designated ``D 5072-92'' by the
American Society for Testing and Materials (ASTM) is being proposed as
an alternate method.

J. Where and How Often Must I Test My Water for Radon?

All CWSs that use ground water must monitor for radon. If your
system relies on ground water or uses ground water to supplement
surface water during low-flow periods, you must monitor for radon. If
you are required to monitor for radon you must collect samples for
analysis at each entry point to the distribution system, after
treatment and storage. Initially all CWSs using ground water must
monitor for radon at each entry point to the distribution system
quarterly for one year. (See Section VII.E for discussion of compliance
dates). If the results of analyses show that the average of all first
year samples at any sample site is above the MCL/AMCL, you must
continue monitoring quarterly at that sampling site until the average
of four consecutive quarterly samples is below the MCL/AMCL. If the
results of analyses show that the average of all first year samples at
each sample site is below the MCL/AMCL, you may reduce monitoring to
once a year at State discretion at each sample site. If the results
indicate that the average of the four quarterly samples are close to
the MCL/AMCL (as discussed next), the State may require you to continue
monitoring quarterly.
The State may allow you to reduce monitoring for radon to a
frequency of once every three-years, if the average from four
consecutive quarterly samples is less than \1/2\ the MCL/AMCL and the
State determines that your system is reliably and consistently below
the MCL/AMCL. However, if a sample collected while monitoring annually
or less frequently exceeds the radon MCL/AMCL, the monitoring frequency
must be increased to quarterly until the average of 4 consecutive
quarterly samples is less than the MCL/AMCL. The State may require the
collection of a confirmation sample(s) to verify the result of the
initial sample. In the case of reduced monitoring, if the analytical
results from any sampling point are found to exceed \1/2\ the MCL/AMCL,
the State may require you to collect a confirmation sample at the same
sampling point. The results of the initial sample and the confirmation
sample(s) will be averaged and the resulting average will be used to
determine compliance. States may, at their discretion, disregard
samples that have obvious sampling errors.
If, after initial monitoring, the State determines that it is
highly unlikely that radon levels in your system will be above the MCL/
AMCL, the State may grant a waiver reducing monitoring frequency to
once every nine years. In granting the waiver, the State must take into
consideration factors such as the geological area of the source water
and previous analytical results which demonstrate that radon levels do
not

[[Page 59253]]

occur above the MCL/AMCL. If you are granted a waiver, it remains in
effect for a nine year period.
If you monitor for radon after proposal of this rule, you may use
the data, at the State's discretion, toward satisfying the initial
sampling requirements for radon. Your monitoring program and the
methods used to analyze for radon must satisfy the regulations set out
in the proposal.

K. May I Use Point-of-Use (POU) Devices, Point-of-Entry (POE) Devices,
or Bottled Water To Comply With This Regulation?

POE aeration or granular activated carbon (GAC) would be allowable
for use to achieve compliance with MCLs. While these POE technologies
are not considered BAT for large systems, they are considered small
system compliance technologies (SSCTs), and thus may serve as BAT under
Sections 1412 and 1415 of the Act for systems serving 10,000 persons or
fewer. Since POU devices are used to treat water at a single tap, radon
will be released at unacceptable levels from the other non-treated
taps, including the shower head. For this reason, POU devices do not
adequately address radon risks and will not be allowed to be used for
compliance purposes. Likewise, although bottled water reduces ingestion
risk from radon, it does not reduce radon-related inhalation risks from
household water. For this reason, compliance determinations based on
bottled water consumption cannot be used.

L. May I Get More Time or Use a Cheaper Treatment? Variances and
Exemptions

Variances and Exemptions (Section 1415.a of the SDWA)
States and Tribes with primary enforcement responsibility
(``primacy'') may issue a variance under Section 1415(a)(1)(A) of the
Act to a CWS that cannot comply with an MCL because of source water
characteristics on condition that the system install the best available
technology. Under Section 1416 of the Act, primacy entities may exempt
a CWS from an NPDWR due to ``compelling factors'', subject to the
restrictions described in the Act. Primacy entities may require systems
to implement additional interim control measures such as installation
of additional centralized treatment or POE devices for each customer as
measures to reduce the health risk before granting a variance or
exemption. The primacy entity must find that the variance or exemption
will not pose an ``unreasonable risk to health'', as determined by the
State or other primacy entity. Guidance for estimating ``unreasonable
risk to health'' (URTH) values for contaminants, including radon, is
being developed by EPA and will result in an upcoming publication (a
draft of the guidance is expected in the Fall of 1999). Preliminary
information regarding URTH values may be found elsewhere (Orme-Zavaleta
1992, USEPA 1998f). States must require CWSs to provide POE devices or
other means, as appropriate to the risks present (i.e., no POU or
bottled water for volatile contaminants, such as radon), to reduce
exposure below unreasonable risk to health values before granting a
variance or exemption.
``Small Systems Variances'' (Section 1415(e) of the SDWA)
For NPDWRs proposed after the 1996 Amendments to the Act, EPA is
required to evaluate the affordability and technical feasibility of
treatment technologies for use as compliance technologies for small
systems. Three categories of small systems will be considered: those
serving: (1) 25-500, (2) 501-3,300, and (3) 3,301-10,000 persons. If
EPA determines that source water conditions exist for one or more small
water system size categories such that typical small systems within a
given category will not be able to afford and/or implement a technology
capable of achieving compliance, then EPA will designate applicable
``small systems variance technologies'' (SSVTs) capable of achieving
contaminant levels that are ``protective of public health''. Primacy
entities may issue small systems variances to eligible CWSs that
install and properly maintain a listed SSVT. For a small system to be
eligible for a small systems variance, the primacy entity must
determine that the system cannot afford to comply through installing
treatment, finding an alternate source of water, or restructuring/
consolidating.
EPA has determined that affordable and technically feasible
technologies exist for radon removal for all classes of small systems.
Under the 1996 SDWA, if EPA lists at least one small systems compliance
technology for a given system size category for all source water
qualities, then it may not list any small systems variance technologies
for that size category, i.e., small systems compliance technologies and
variance technologies are mutually exclusive. For this reason, no small
system will be eligible for a small systems variance for radon under
the SDWA (Section 1415(e)). Small systems may be eligible for general
variances (under Section 1415.a of the Act) and/or exemptions on a case
by case basis. It is also important to emphasize that the presumptive
regulatory expectation for small systems is an MMM program (in the
absence of a State MMM program) and compliance with the AMCL of 4000
pCi/L. Thus, for the vast majority of small systems (those with radon
levels below 4000 pCi/L), compliance with this proposed rule will not
involve any treatment of drinking water.

M. What Are State Primacy, Record Keeping, and Reporting Requirements?

The proposed Radon Rule requires States to adopt several regulatory
requirements, including public notification requirements, MCL/AMCL for
radon, and the requirements of Subpart R in the proposed rule. In
addition, States and eligible Indian tribes will be required to adopt
several special primacy requirements for the Radon Rule. The proposed
rule includes additional reporting requirements for MMM program plans.
The proposed rule also requires States to keep specific records in
accordance with existing regulations. These requirements are discussed
in more detail in Section IX of this preamble.

N. How Are Tribes Treated in This Proposal?

The proposal provides Tribes the option of seeking ``treatment in
the same manner as a State'' for the purposes of assuming enforcement
responsibility for a CWS program, and developing and implementing an
MMM program (see Section VI.C). If a Tribe chooses not to implement an
EPA-approved MMM program, any tribal CWS may develop an MMM plan for
EPA approval, under the same criteria described in Section VI.A.

Statutory Requirements and Regulatory History

II. What Does the Safe Drinking Water Act Require the EPA To Do
When Regulating Radon in Drinking Water?

The 1996 Amendments to the Safe Drinking Water Act (PL 104-182)
establish a new charter for public water systems, States, Tribes, and
EPA to protect the safety of drinking water supplies. (For an overview
of the general requirements for all drinking water regulations, see
Section XVI of this preamble). Among other mandates, Congress amended
Section 1412 of the SDWA to direct EPA to take the following actions
regarding radon in drinking water.

[[Page 59254]]

A. Withdraw the 1991 Proposed Regulation for Radon

Congress specified that EPA should withdraw the drinking water
standards proposed for radon in 1991 (see discussion in Section III.D).

B. Arrange for a National Academy of Sciences Risk Assessment

The amendments in Section 1412(b)(13)(B) require EPA to arrange for
the National Academy of Sciences (NAS) to conduct an independent risk
assessment for radon in drinking water and an assessment of the health
risk reduction benefits from various mitigation measures to reduce
radon in indoor air.

C. Set an MCLG, MCL, and BAT for Radon-222

Congress specified in Section 1412 (b)(13) that EPA should propose
a new MCLG and NPDWR for radon-222 by August, 1999. EPA is also
required to finalize the regulation by August, 2000. As a preliminary
step, EPA was required to publish a radon health risk reduction and
cost analysis (HRRCA) for possible radon MCLs for public comment by
February, 1999. As required by SDWA, this analysis addressed: (1)
Health risk reduction benefits that come directly from controlling
radon; (2) health risk reduction benefits likely to come from
reductions in contaminants that occur with radon; (3) costs; (4)
incremental costs and benefits associated with each MCL considered; (5)
effects on the general population and on groups within the general
population likely to be at greater risk; (6) any increased health risk
that may occur as the result of compliance; and (7) other relevant
factors, including the quality and extent of the information, the
uncertainties in the analysis, and factors with respect to the degree
and nature of the risk.

D. Set an Alternative MCL (AMCL) and Develop Multimedia Mitigation
(MMM) Program Plan Criteria

The amendments in Section 1412(b)(13)(F) introduced two new
elements into the radon in drinking water rule: (1) An Alternative
Maximum Contaminant Level (AMCL), and (2) radon multimedia mitigation
(MMM) programs. If the MCL established for radon in drinking water is
more stringent than necessary to reduce the contribution to radon in
indoor air from drinking water to a concentration that is equivalent to
the national average concentration of radon in outdoor air, EPA is
required to simultaneously establish an AMCL. The AMCL would be the
standard that would result in a contribution of radon from drinking
water to radon levels in indoor air equivalent to the national average
concentration of radon in outdoor air. If an AMCL is established, EPA
is to publish criteria for State multimedia mitigation (MMM) programs
to reduce radon levels in indoor air. Section VI of this preamble
describes what a State or public water system must have in their
multimedia mitigation program plan.

E. Evaluate Multimedia Mitigation Programs Every Five Years

Once the MMM programs are established, EPA must re-evaluate them no
less than every five years (Section 1412(b)(13)(G)). EPA may withdraw
approval of programs that are not expected to continue to meet the
requirement of achieving equal or greater risk reduction.

III. What Actions Has EPA Taken on Radon in Drinking Water Prior to
This Proposal?

A. Regulatory Actions Prior to 1991

Section 1412 of the SDWA, as amended in 1986, required the EPA to
publish Maximum Contaminant Level Goals (MCLGs) and to promulgate
NPDWRs for contaminants that may cause an adverse effect on human
health and that are known or anticipated to occur in public water
supplies. On September 30, 1986, EPA published an advance notice of
proposed rulemaking (ANPRM) (51 FR 34836) concerning radon-222 and
other radionuclides. The ANPRM discussed EPA's understanding of the
occurrence, health effects, and risks from these radionuclides, as well
as the available analytical methods and treatment technologies, and
sought additional data and public comment on EPA's planned regulation.
EPA's Science Advisory Board (SAB) reviewed the ANPRM and the four
draft criteria documents that supported it prior to publication of the
ANPRM in the Federal Register. EPA subsequently revised the criteria
documents and resubmitted them to the SAB for review during the summer
of 1990. EPA then revised the criteria documents based on this
additional round of SAB review and presented a summary of the SAB
comments and the Agency's responses in a 1991 Notice of Proposed
Rulemaking (NPRM).

B. The 1991 NPRM

On July 18, 1991 (56 FR 33050), EPA proposed a NPDWR for radon and
the other radionuclides addressed in the 1986 ANPRM. The 1991 notice,
which built on and updated the information assembled for the 1986
ANPRM, proposed an MCLG, an MCL, BAT, and monitoring, reporting, and
public notification requirements for radon in public water supplies.
The proposed MCLG was zero, the proposed MCL was 300 pCi/L, and the
proposed BAT was aeration. Under the proposed rule, all CWSs and
NTNCWSs relying on ground water would have been required to monitor
radon levels quarterly at each point of entry to the distribution
system. Compliance monitoring requirements were based on the arithmetic
average of four quarterly samples. The 1991 proposed rule required
systems with one or more points of entry out of compliance to treat
influent water to reduce radon levels below the MCL or to secure water
from another source below the MCL.
The proposed rule was accompanied by an assessment of regulatory
costs and economic impacts, as well as an assessment of the risk
reduction associated with implementation of the MCL. EPA estimated the
following potential impacts from the 1991 proposed MCL:
An estimated lifetime cancer risk of about two cancers for
every 10,000 persons exposed to radon in drinking water.
Avoidance of about 80 cancer cases per year.
About 27,000 public water systems affected.
A total annual cost of about $180 million.
The Agency received substantial comments on the proposal and its
supporting analyses from States, water utilities, and other stakeholder
groups. EPA has included in Appendix I of this preamble a summary of
major public comments on the 1991 NPRM and how EPA subsequently
addressed those comments.

C. 1994 Report to Congress: Multimedia Risk and Cost Assessment of
Radon

In 1992, Congress directed EPA to report on the multimedia risks
from exposure to radon, the costs to control this exposure, and the
risks from treating to remove radon. EPA's 1994 Report to Congress
(USEPA 1994a) estimates the risk, fatal cancer cases, cancer cases
avoided and costs for mitigating radon in water and in indoor air. The
Report found that cancer risks from radon in both air and water are
high. While radon risk in air typically far exceeds that in water, the
cancer risk from radon in water is higher than the cancer risk
estimated to result from any other currently regulated drinking water
contaminant.
EPA conducted a quantitative uncertainty analysis of the risks
associated with exposure to radon in

[[Page 59255]]

drinking water. This analysis, reviewed by EPA's SAB at the direction
of Congress, found that:
People are exposed to waterborne radon in three ways: (1)
From ingesting radon dissolved in water; (2) from inhaling radon gas
released from water during household use; and (3) from inhaling radon
progeny derived from radon released from water.
The estimated total U.S. cancer fatalities per year from
unregulated waterborne radon via all three routes of exposure were 192,
with a range from about 51 to 620.
The estimated annual cost was $272 million.
The 1994 Report to Congress noted that the regulated industry
estimated considerably higher costs than EPA for a 300 pCi/L MCL. For
example, in October 1991 the American Water Works Association (AWWA)
estimated national costs at $2.5 billion/year (for discussion of this
issue, see Section G of the Appendix to this preamble). The final part
of the report included the SAB's comments on each analysis presented
and an EPA discussion of the issues raised by the SAB.

D. 1997 Withdrawal of the 1991 NPRM for Radon-222

As required by the SDWA as amended, EPA withdrew the MCLG, MCL, and
monitoring, reporting, and public notification requirements proposed in
1991 for radon-222 on August 6, 1997 (62 FR 42221). No other provision
of the 1991 proposal was affected by this withdrawal.

E. 1998 SBREFA Small Business Advocacy Review Panel for Radon

In 1998, EPA convened a Small Business Advocacy Review Panel to
address the radon rule, in accordance with the Regulatory Flexibility
Act (RFA) as amended by the Small Business Regulatory Enforcement
Fairness Act (SBREFA). The Panel of representatives from EPA, the
Office of Management and Budget's Office of Information and Regulatory
Affairs, and the Small Business Administration's Office of Advocacy
reviewed technical background information related to this rulemaking,
and reviewed comments provided by small business and government
entities affected by this rule. The Panel made recommendations in a
final report to the Administrator which included a discussion of how
the Agency could accomplish its environmental goals while minimizing
impacts to small entities. For additional details, see Section XIV.B of
this proposal.

F. 1999 HRRCA for Radon in Drinking Water

EPA published the Health Risk Reduction and Cost Analysis required
by the SDWA on February 26, 1999 (64 FR 9559), and took public comment
for 45 days. EPA held a one-day public meeting in Washington, D.C. on
March 16, 1999, to present the HRRCA and the latest MMM framework, and
discuss stakeholder questions and issues. For details of the contents
of the HRRCA and EPA's response to significant public comment, see
Section XIII of this preamble.

Requirements

IV. To Which Water Systems Does This Regulation Apply?

The SDWA directs EPA to develop national primary drinking water
regulations (NPDWRs) that apply to public water systems (PWSs). The
statute defines a PWS as a system that provides water to the public for
human consumption if such system has at least 15 service connections or
regularly serves at least 25 individuals (Section 1401(4)(A)). EPA's
regulations at 40 CFR 141.2 define different types of PWSs. A community
water system (CWS) serves at least 15 service connections used by year
round residents or regularly serves at least 25 year-round residents. A
non-community system does not serve year-round residents; rather, it
(1) regularly serves at least 25 of the same persons over 6 months of
the year (a ``non-transient'' system such as a restaurant or church) or
(2) does not serve at least 25 of the same persons over 6 months of the
year (a ``transient'' system such as a campground or service station).
The regulation for radon in drinking water and the multimedia
approach for reduction of radon in indoor air (MMM program) proposed in
this notice applies only to CWSs that use ground water or mixed ground
and surface water (see following discussion regarding ``mixed''
supplies). The proposed regulation does not apply to transient water
systems because most people who use such facilities do so only
occasionally (e.g., travelers). There is no evidence that such short-
term exposure to radon would cause acute illness. The data on which
health risks from radon were determined for this rulemaking reflect
long-term exposure (see chapter 3 of the RIA (USEPA 1999f) HRRCA
section that discusses calculation of risk). And, as discussed next in
the context of non-transient non-community systems, even workers at
transient facilities who regularly drink the water would be expected to
have much less exposure than persons served by community water systems.
For these reasons, the proposed rule does not cover transient systems.
The proposed regulation also does not apply to non-transient non-
community (NTNC) water systems. EPA has determined that the risks posed
to persons served by NTNC systems (such as factories, hospitals, and
schools with their own drinking water wells) are substantially less
than the risks to persons served by community water systems.
The Agency recently completed a preliminary analysis of radon
occurrence (using data provided by six States), exposure and risk at
NTNC public water systems. Results from this preliminary analysis
indicate that even though radon concentrations are likely to be about
60 percent higher at NTNC locations than at locations served by a
community water system, the lifetime average risk to individuals who
work or attend school in buildings served by a groundwater-based NTNC
system is probably about 17 percent of the average risk to a worker
(and 6.7 percent of the average risk to a student) exposed in a home
served by a community ground water system. The reason that risks are
lower in the NTNC setting than the residential setting is that people
who are exposed at NTNC locations spend a smaller fraction of their
lifetime there than in the home. Further, in the particular case of
students most do not spend their entire school years in the same
school. EPA also notes that there is limited data in this area, and
more information is needed on how water is used in NTNC facilities and
on the contribution NTNC water use makes to radon inhalation risk. In
addition, the overall population served by NTNC PWSs is relatively
small (5.2 million vs. 89.7 million in homes served by CWSs using
ground water (USEPA 1999b)).
EPA acknowledges that the SDWA applies to all public water systems.
However, EPA believes that limiting the applicability of the radon rule
to community water systems where the risk from radon exposure is the
greatest meets a major goal of Congress in enacting the 1996 amendments
to the Act-to focus regulations on the most significant problems. In
the Conference Report adopting the 1996 amendments, Congress finds that
``more effective protection of public health requires--a Federal
commitment to set priorities that will allow scarce Federal, State, and
local resources to be targeted toward the drinking water problems of
greatest public health concerns. `` H. Rep. 104-182, Sec. 3. Moreover,
Congress specifically directed EPA in setting the NPDWRs for radon to
take into

[[Page 59256]]

consideration the costs and benefits of control programs for radon from
other sources. EPA has used this authority in this proposal to set the
MCL at 300 pCi/L and to encourage small systems to implement the MMM
program and comply with the AMCL. In both circumstances, EPA took into
account the fact that programs to control radon in indoor air promise
greater benefits at considerably less cost. EPA believes this cost-
effectiveness factor is also relevant in determining the applicability
of the radon rule. EPA's preliminary analysis of the risk associated
with exposure to radon from NTNC systems is that it is much less than
the risk from exposure from CWSs. For this reason, EPA has determined
that it is not cost-effective to regulate these systems.
However, it is important to note that this analysis is based on
limited occurrence and exposure data. In particular, relatively little
is known about the transfer factor for release of radon from water into
indoor air at NTNC locations, or about the equilibrium factor affecting
the amount of radon in indoor air at such locations. The calculations
done by EPA to date have assumed that certain values for these
parameters at NTNC locations are similar to those in homes, although
the data are limited.
The EPA is soliciting comment on the proposal to exclude NTNC PWSs
from the radon regulation. EPA is soliciting comments on the Agency's
preliminary analysis of radon exposure in NTNC PWSs, as well as any
additional data on key parameters, including data on the release of
radon from drinking water in the types of buildings (e.g., restaurants,
factories, churches, etc.) supplied by NTNC PWSs, and occurrence of
radon in NTNC PWSs. If information by commenters shows a greater
opportunity for risk reduction than identified in its initial analysis,
EPA may make the final radon rule applicable to NTNC PWSs without
further public comment.
With regard to systems using mixed ground and surface water,
current regulations require that all systems that use any amount of
surface water as a source be categorized as surface water systems. This
classification applies even if the majority of water in a system is
from a ground water source. Data currently in SDWIS does not identify
how many of these mixed systems exist although this information would
help the Agency to better understand regulatory impacts. To the extent
that systems correctly classified by SDWIS as surface water systems
also use ground water that may exceed the MCL/AMCL for radon, the costs
and benefits of the current proposal will be underestimated.
EPA is investigating ways to identify how many mixed systems exist
and how many mix their ground and surface water at the same entry point
or at separate entry points within the same distribution systems. For
example, a system may have several plants/entry points that feed the
same distribution system. One of these entry points may mix and treat
surface water with ground water prior to its entry into the
distribution system. Another entry point might use ground water
exclusively for its source while a different entry point would
exclusively use surface water. However, all three entry points would
supply the same system classified in SDWIS as surface water.
One method EPA could use to address this issue would be to analyze
Community Water System Survey (CWSS) data then extrapolate this
information to SDWIS to obtain a national estimate of mixed systems.
CWSS data, from approximately 1,900 systems, breaks down sources of
supply at the level of the entry point to the distribution system and
further subdivides flow by source type. The Agency could use the
national estimate of mixed systems to regroup surface water systems for
certain impact analyses when regulations only impact one type of
source. The Agency requests comment on this methodology and its
applicability for use in regulatory impact analyses.

V. What Is the Proposed Maximum Contaminant Level Goal for Radon?

A. Approach To Setting the Maximum Contaminant Level Goal (MCLG)

Under Section 1412(b)(4) of the SDWA, the EPA must establish
maximum contaminant level goals (MCLG) at the level at which no known
or anticipated adverse effects on the health of persons occur, and
which allow an adequate safety margin. Section 1412(b)(13) requires the
Administrator to set an MCLG for radon in drinking water.

B. MCLG for Radon in Drinking Water

As described in Section XII of this preamble, radon is a documented
human carcinogen, classified by EPA as a Group A carcinogen (i.e.,
there is sufficient evidence of a causal relationship between exposure
to radon and lung cancer in humans). Radon is classified as a known
human carcinogen based on data from epidemiological studies of
underground miners. This finding is supported by a consensus of opinion
among national and international health organizations. The
carcinogenicity of radon has been well established by the scientific
community, including the Biological Effects of Ionizing Radiation (BEIR
VI) Committee of the National Academy of Sciences (NAS 1999a), the
National Institute of Environmental Health Sciences, U.S. Department of
Health and Human Services, the World Health Organization's
International Agency for Research on Cancer (IARC 1988), the
International Commission on Radiological Protection (ICRP 1987), and
the National Council on Radiation Protection and Measurement (NCRP
1984). In addition, the Centers for Disease Control, the American Lung
Association, the American Medical Association, the American Public
Health Association and others have recognized radon as a significant
public health problem.
Based on the well-established human carcinogenicity of radon, and
of ionizing radiation in general, the Agency is proposing an MCLG of
zero for radon in drinking water. This decision is also supported by
the NAS' current recommendation for a linear non-threshold relationship
between exposure to radon and cancer in humans. In the BEIR VI report
(NAS 1999a), the NAS concluded that there is good evidence that a
single alpha particle (high-linear energy transfer radiation) can cause
major genomic changes in a cell, including mutation and transformation
that potentially could lead to cancer. They noted that even if
substantial repair of the genomic damage were to occur, ``the passage
of a single alpha particle has the potential to cause irreparable
damage in cells that are not killed.'' Given the convincing evidence
that most cancers originate from damage to a single cell, the committee
went on to conclude that ``On the basis of these [molecular and
cellular] mechanistic considerations, and in the absence of credible
evidence to the contrary, the committee adopted a linear non-threshold
model for the relationship between radon exposure and lung-cancer risk.
However, the BEIR VI committee recognized that it could not exclude the
possibility of a threshold relationship between exposure and lung
cancer risk at very low levels of radon exposure.'' The NAS committee
on radon in drinking water (NAS 1999b) reiterated the finding of the
BEIR VI committee's comprehensive review of the issue, that a
``mechanistic interpretation is consistent with linear non-threshold
relationship between radon exposure and cancer risk''. The committee
noted that the ``quantitative

[[Page 59257]]

estimation of cancer risk requires assumptions about the probability of
an exposed cell becoming transformed and the latent period before
malignant transformation is complete. When these values are known for
singly hit cells, the results might lead to reconsideration of the
linear no-threshold assumption used at present.'' EPA recognizes that
research in this area is on-going but is basing its regulatory
decisions on the best currently available science and recommendations
of the NAS that support use of a linear non-threshold relationship. For
additional information on this issue see Section XII.C.3. ``Biologic
Basis of Risk Estimation'' of this preamble.

VI. What Must a State or Community Water System Have in Its
Multimedia Mitigation Program Plan?

Today's proposed rule provides States (as defined in Section 1401
of the SDWA) with alternatives for controlling radon exposure. States
can develop a MMM program for the reduction of the higher risk of radon
in indoor air together with an alternative MCL (AMCL) of 4000 pCi/L to
address the highest levels of exposure from radon in drinking water. If
a State does not choose this option, the community water systems (CWS)
in that State must develop and implement local MMM program plans or
comply with an MCL of 300 pCi/L. See Section VII for information on the
regulatory expectations for CWSs.

A. What Are the Criteria?

1. Overview
EPA has identified four criteria that State MMM program plans are
required to meet to be approved by EPA. MMM program plans developed by
Indian tribes will be reviewed by EPA, according to these same
criteria. CWSs developing local MMM programs are also subject to these
criteria. These four criteria are: public participation, setting
quantitative goals, strategies for achieving goals, and a plan to track
and report results.
The criteria are based on a number of factors. Foremost, the
criteria reflect the elements found in successful voluntary action
programs for radon in indoor air that have been underway for more than
a decade. It is estimated that at the end of the year 2000, voluntary
programs to test homes and mitigate elevated radon levels in indoor air
and to encourage the construction of ``radon-resistant'' new homes will
have saved some 2500 lives; and, there is much more that can be done.
In the 1999 BEIR VI report (NAS 1999a), NAS concluded that 5,000 to
7,000 cancer cases (using two different methods) could be avoided
annually if all homes were below EPA's voluntary radon action level of
4 pCi/L of air. Incorporating these program elements into the criteria
required for the MMM programs builds on successful efforts and can be
expected to result in an even greater number of lives saved as more
States adopt programs and existing programs are strengthened and
expanded.
EPA has developed criteria that allow considerable flexibility for
those developing and expanding programs. EPA was urged by States and
other stakeholders to avoid prescribing the specific elements of the
MMM program in a ``one size fits all'' approach. States and CWSs
adopting MMM programs will be required to set quantitative goals for
mitigating elevated levels of radon in indoor air of existing homes and
building radon-resistant new homes, and to initiate strategies to
promote and increase these activities. However, there are requirements
that will be new to many of the State indoor radon programs. Those
adopting MMM programs will be required to involve the public in a
number of important (and on-going) ways, and to track and report
results from the implementation of the programs. With these additional
elements, both the affected public and EPA will be able to assess the
success of the MMM programs. Stakeholder input and EPA's experience
with the national voluntary program and the State indoor radon programs
led EPA to conclude that these criteria will provide the basis for a
program that meets the statutory directive for equal or greater risk
reduction benefits.
The Agency also considered equity-related issues concerning the
potential impacts of MMM program implementation. There is no factual
basis to indicate that minority and low income or other communities are
more or less exposed to radon in drinking water than the general
public. However, some stakeholders expressed more general concerns
about equity in radon risk reduction that could arise from the MMM/AMCL
framework outlined in SDWA. One concern is the potential for an uneven
distribution of risk reduction benefits across water systems and
society. Under the proposed framework for the rule, customers of CWSs
complying with the AMCL could be exposed to a higher level of radon in
drinking water than if the MCL were implemented, though this level
would not be higher than the background concentration of radon in
ambient air. However, these CWS customers could also save the cost,
through lower water rates, of installing treatment technology to comply
with the MCL. Under the proposed regulation, CWSs and their customers
have the option of complying with either the AMCL (associated with a
State or local MMM program) or the MCL. EPA believes it is important
that these issues and choices be considered in an open public process
as part of the development of MMM program plans. Therefore, EPA has
incorporated requirements into the proposed rule that provide a
framework for consideration of equity concerns with the MMM/AMCL.
First, the proposed rule includes requirements for public participation
in the development of MMM program plans, as well as for notice and
opportunity for public comment. EPA believes that the requirement for
public participation will result in State and CWS program plans that
reflect and meet their different constituents' needs and concerns and
that equity issues can be most effectively dealt with at the State and
local levels with the participation of the public. In developing their
MMM program plans, States and CWSs are required to document and
consider all significant issues and concerns raised by the public. EPA
expects and strongly recommends that States and CWSs pay particular
attention to addressing any equity concerns that may be raised during
the public participation process. In addition, EPA believes that
providing CWS customers with information about the health risks of
radon and on the AMCL and MMM program option will help to promote
understanding of the health risks of radon in indoor air, as well as in
drinking water, and help the public to make informed choices. To this
end, EPA is requiring CWSs to alert consumers to the MMM approach in
their State in consumer confidence reports issued between publication
of the final radon rule and the compliance dates for implementation of
MMM programs. This will include information about radon in indoor air
and drinking water and where consumers can get additional information.
EPA is encouraging the States to elect to develop and implement
State-wide MMM program plans. Since almost all States currently have
State indoor radon programs, EPA considers the States to be best
positioned to develop strong MMM program plans that, when implemented,
will be expected to achieve equal or greater radon risk reduction when
compared to compliance with the MCL. For example, a State-wide plan can
take into account the within-State variations in indoor radon
potential, the differences in radon

[[Page 59258]]

levels in drinking water, the experienced coalitions and cooperative
partners that have been working to promote public action on indoor
radon, the technical expertise of State drinking water and indoor radon
programs, and many other factors. EPA expects that the States will be
best positioned to develop MMM program plans that are robust and
credible in terms of the level of public participation in the
development and review process, the goals that are to be achieved from
implementation of MMM, and the program strategies to be used.
In the development of State MMM program plans meeting EPA's
criteria and in the implementation of the State's MMM program plan, EPA
expects and strongly recommends that the State's programs responsible
for drinking water and for indoor radon coordinate and collaborate on
their efforts. This is particularly important because of the uniqueness
of the MMM/AMCL approach which addresses radon risk reduction in
drinking water and in indoor air in a multimedia manner that is outside
the normal regulatory structure for drinking water. Both programs have
important responsibilities and roles in making the AMCL and MMM program
approach successful in achieving optimal radon risk reduction. To this
end, EPA has included as a special primacy requirement (see Section
142.16 of the proposed rule) that States include in their primacy
revision application for the AMCL a description of the extent and
nature of coordination between the State's interagency programs (i.e.,
indoor radon and drinking water programs) on development and
implementation of the MMM program plan, including the level of
resources that will be made available for implementation and
coordination between these agencies.
CWSs developing local MMM program plans are also subject to these
criteria. CWS MMM program plans developed in the absence of a State
program are deemed to be approved by EPA if they meet the same criteria
and are approved by the State. States without a MMM program, as a
special condition of primacy (see Section 142.16 of the proposed rule),
will be required to review and approve local CWS MMM program plans and
to submit their process for approving such plans to EPA. The Agency
considered an approach under which it would directly review and approve
CWS MMM program plans. However, for several reasons, EPA is proposing
that States review local MMM program plans. EPA believes that
responsibility for such reviews is an appropriate and natural extension
of the States' primacy responsibilities for oversight and enforcement
of drinking water regulations. State review and approval of local MMM
program plans will ensure that all elements of the radon rulemaking--
both the MMM program as well as implementation of the AMCL/MCL--are
enforced through the State, rather than separating elements of the rule
between the Federal and State governments. Dividing responsibility in
such a way may complicate implementation of both elements of the radon
rule and be confusing to both CWSs and the public. EPA also believes
that the States are best positioned to assist CWSs, especially small
systems, in the development of local MMM programs plans to review and
approve local plans that meet the four criteria. States have a direct
and ongoing regulatory relationship with CWSs as a part of their
primacy authorities, as well as a major responsibility for public
health related policy and programs in the State. In addition, States
are aware of and sensitive to local public health needs and concerns,
as well as other issues, that may need to be considered in the
development and implementation of local MMM programs. For all these
reasons, EPA is proposing an approach today that would require the
States to review and approve local MMM program plans in accordance with
the same criteria used in EPA's review of State MMM program plans.
However, EPA solicits comments on other approaches, such as EPA review
and approval of local MMM program plans or other options intermediate
between sole State or sole Federal responsibility.
EPA anticipates, and recommends, that States would assist CWSs in
developing their local MMM program plans and would approve program
plans that meet the criteria and that reflect local radon
implementation issues as discussed in Section VI.F. In non-MMM States,
EPA is also including as a special primacy requirement that States
include in their primacy revision application for the MCL a description
of the extent and nature of coordination between interagency programs
(i.e., indoor radon and drinking water programs) on development and
implementation of the State's review and approval process for CWS MMM
program plans, including the level of resources will be made available
for implementation and coordination between these agencies.
2. Criteria for MMM Program Plans
The following four criteria are required for approval of State MMM
program plans by EPA. Local MMM program plans developed by community
water systems are deemed to be approved by EPA if they meet these
criteria (as appropriate for the local level) and are approved by the
State. The term ``State'', as referenced next, includes States, Indian
tribes and community water systems. EPA is requesting comment on each
of the criteria for approval of State, and CWS, MMM program plans. In
particular, EPA is requesting comment on whether the criteria need to
be more or less stringent, and the supporting rationale for EPA's
consideration of other potentially credible approaches.
(a) Description of Process for Involving the Public. (1) States are
required to involve community water system customers, and other sectors
of the public with an interest in radon, both in drinking water and in
indoor air, in developing their MMM program plan. The MMM program plan
must include:

A description of processes the State used to provide for public
participation in the development of its MMM program plan, including the
components identified in the following paragraphs b, c, and d;
A description of the nature and extent of public participation that
occurred, including a list of groups and organizations that
participated;
A summary describing the recommendations, issues, and concerns arising
from the public participation process and how these were considered in
developing the State's MMM program plan; and,
A description of how the State made information available to the public
to support informed public participation, including information on the
State's existing indoor radon program activities and radon risk
reductions achieved, and on options considered for the MMM program plan
along with any analyses supporting the development of such options.
(2) Once the draft program plan has been developed, the State must
provide notice and opportunity for public comment on the draft plan
prior to submitting it to EPA.
(b) Quantitative Goals. (1) States are required to establish and
include in their plans quantitative goals, to measure the effectiveness
of their MMM program, for the following:
(i) Existing houses with elevated indoor radon levels that will be
mitigated by the public; and,
(ii) New houses that will be built radon-resistant by home
builders.
EPA is proposing to require establishing quantitative goals in
these

[[Page 59259]]

two areas because they represent the most direct link to the risk
reduction benefits that are the ultimate objective of the MMM programs.
In addition, EPA analyses indicate that it is very cost-effective to
test and mitigate existing homes with elevated indoor radon levels. It
is also very cost-effective to build new homes radon-resistant,
especially in higher radon potential areas. In the existing indoor
radon program, EPA has been encouraging the States to promote testing
and mitigation in all areas of a State. EPA has also encouraged the
States to focus on their activities to promote radon-resistant new
construction on the highest radon potential areas (Zone 1) where
building homes radon-resistant is most cost-effective. However, it is
also cost-effective to build homes in medium potential areas (Zone 2),
as well as in ``hot'' spots found in most lower radon potential areas
(Zone 3).
EPA recognizes the States' (and CWSs') need for flexibility in
designing MMM programs reflecting their needs and circumstances, in
particular the extent to which opportunities are available for risk
reduction in mitigation of existing homes with elevated indoor radon
levels or in construction of new homes built radon-resistant. Some
States, in particular those with a preponderance of lower radon
potential areas (and for CWSs in lower radon potential areas), may find
it preferable to focus more heavily on testing and mitigation of
existing housing than on radon-resistant new construction.
EPA is requesting comment on whether there are alternative goals
that achieve radon risk reduction and the rationale for those goals.
EPA is also soliciting comments on the goals outlined in paragraph (b),
in particular on the appropriateness of the goals and whether the goals
need to be more or less stringent.
(2) These goals must be defined quantitatively either as absolute
numbers or as rates. If goals are defined as rates, a detailed
explanation of the basis for determining the rates must be included.
EPA is proposing to provide this option, in part, because
opportunities available for risk reduction in mitigation of existing
homes with elevated indoor radon levels or in construction of new homes
built radon-resistant may vary between States and within States. In
addition, the level of new home construction may vary from year to year
in different parts of a State or in a local jurisdiction. In this
situation, it may be more appropriate to set goals for radon-resistant
new construction as a rate, rather than absolute numbers, to account
for this variability. This may be especially true for CWS developing
local MMM program plans where no new home construction is currently
taking place but may in the future.
(3) States are required to establish goals for promoting public
awareness of radon health risks, for testing of existing homes by the
public, for testing and mitigation of existing schools, and for
construction of new public schools to be radon-resistant, or to include
an explanation of why goals were not established in these program
areas.
EPA is proposing that States have this option of defining goals as
absolute numbers or as rates because, while awareness of radon health
risks is a necessary element and a first step in getting the public to
take action on indoor radon, public awareness, in and of itself, does
not constitute radon exposure reduction. It does, however, help to
facilitate informed choice by the public regarding radon testing and
mitigation. Since the level of awareness on the health effects of radon
is already high in many States, EPA is proposing to give flexibility to
the States on this goal. In the case of radon in schools, many States
have undertaken a range of activities to address radon in schools and
some have done extensive testing, in some cases passing State
legislation requiring the State to test public schools. Therefore, EPA
is proposing to give States the option of setting these goals for
schools. Although this approach provides flexibility in goal setting,
EPA strongly encourages those States which do not have high levels of
public awareness on radon and where there has been limited testing of
public schools across the State to set goals in these areas. EPA is
soliciting comment on whether States should be required to set
quantitative goals in all or some of these areas in paragraph (b)(3).
(c) Implementation Plans. (1) States are required to include in
their MMM program plan implementation plans outlining the strategic
approaches and specific activities the State will undertake to achieve
the quantitative goals identified in paragraphs (b)(1) and (b)(2). This
must include implementation plans in the following two key areas:
(i) Promoting increased testing and mitigation of existing housing
by the public through public outreach and education and during
residential real estate transactions.
(ii) Promoting increased use of radon-resistant techniques in the
construction of new homes.
(2) If a State has included goals for promoting public awareness of
radon health risks; promoting testing of existing homes by the public;
promoting testing and mitigation of existing schools; and promoting
construction of new public schools to be radon resistant, then the
State is required to submit a description of the strategic approach
that will be used to achieve the goals.
(3) States are required to provide the overall rationale and
support for why their proposed quantitative goals identified in
paragraphs (b)(1) and (b)(2), in conjunction with their program
implementation plans, will satisfy the statutory requirement that an
MMM program be expected to achieve equal or greater risk reduction
benefits to what would have been expected if all public water systems
in the State complied with the MCL.
(d) Plans for Measuring and Reporting Results. (1) States are
required to include in the MMM plan submitted to EPA a description of
the approach that will be used to assess the results from
implementation of the State MMM program, and to assess progress towards
the quantitative goals in paragraphs (b)(1) and (b)(2). This
specifically includes a description of the methodologies the State will
use to determine or track the number of existing homes with elevated
levels of radon in indoor air that are mitigated and the number or the
rate of new homes built radon-resistant. This must also include a
description of the approaches, methods, or processes the State will use
to make the results of these assessment available to the public.
(2) If a State includes goals in paragraph (b)(3) for promoting
public awareness of radon health risks; testing of existing homes by
the public; testing and mitigation of existing schools; and,
construction of new public schools to be radon-resistant; the State is
required to submit a description of how the State will determine or
track progress in achieving each of these goals. This must also include
a description of the approaches, methods, or processes the State will
use to make these results available to the public.

B. Why Will MMM Programs Get Risk Reduction Equal or Greater Than
Compliance With the MCL?

The National Indoor Radon Program implemented by EPA, States and
others, has achieved substantial risk reduction through voluntary
public action since the release of the original ``A Citizen's Guide to
Radon'' in 1986 (USEPA 1986) (updated: USEPA 1992b) and the U.S.
Surgeon General's recommendation in 1988 (US EPA, 1988b) that all homes
be tested and elevated radon levels be reduced. The program has been

[[Page 59260]]

successful in achieving voluntary risk reduction on indoor radon
through a variety of program strategies. It is important to keep in
perspective the comparatively large potential for risk reduction that
can be achieved if all existing homes with indoor radon levels at or
above EPA's voluntary action level for indoor radon of 4 pCi/L in the
U.S. were mitigated (approximately 6 million homes). In addition there
is the potential for significant risk reduction potential if the
approximately 1 million new homes built annually in the U.S. were built
radon-resistant. Based on the estimated number of existing homes fixed
and the number of new homes built radon-resistant since the national
program began in 1986, EPA estimates that a total of more than 2,500
lives will be saved through voluntary indoor radon risk reduction
efforts expected to take place up through the year 2000. Every year the
rate of lives saved increases as more existing houses with elevated
radon levels are fixed and as more new houses are built radon-
resistant. On average this rate of lives that will be saved from these
risk reduction actions increases by about 30 additional lives per year.
EPA estimates that for the year 2000, the rate of radon-related lung
cancer deaths that will be avoided from mitigation of existing homes
and from homes built radon-resistant in high radon areas will be about
350 lives saved per year (USEPA 1999i).
Under the radon provision of SDWA, if all States adopted the AMCL,
all State MMM programs together must be expected to result in at
minimum about 62 cancer deaths averted annually; equal to what would be
achieved with universal compliance with the MCL. Unlike these health
risk reduction benefits which remain constant from one year to the
next, the rate of health benefits from reducing radon in indoor air, as
noted previously, steadily increases every year with every additional
existing home that is mitigated and with every new home built radon-
resistant. This steady incremental risk reduction offered by mitigation
of existing homes with elevated indoor radon and building homes radon-
resistant, especially during real estate transactions and through
builder and consumer education and State and local adoption of radon-
resistant building codes, holds the potential for substantial long-term
risk reduction. NAS in their 1999 BEIR VI Report, concluded that up to
one third (i.e., 5,000 to 7,000) of their estimated 15,000 to 22,000
annual radon-related lung cancer deaths in the U.S. could be avoided if
all homes were below EPA's voluntary radon action level of 4 pCi/L of
air (NAS 1999a). This does not include the risk reduction that is
achieved from new homes built radon-resistant. The one million new
homes on average being built every year represent a significant radon
risk reduction opportunity. Therefore, a critical element for MMM is to
utilize and build on the indoor radon program framework to achieve
``equal or greater'' risk reduction rather than focusing efforts on
precisely quantifying the much more limited risk reduction that will
not occur in community water systems complying with the AMCL (i.e., the
difference in the risk reduction between the MCL and the AMCL).
C. Implementation of an MMM Program in Non-Primacy States
A State that does not have primary enforcement responsibility for
the Public Water System Program under Section 1413 of the SDWA
(``primacy'') and where EPA administers the CWS program may still
develop a State-wide MMM program plan. EPA would not expect to develop
an MMM program plan where the State elects not to develop a State-wide
MMM program plan. Accordingly, CWSs in such jurisdictions would be
required to comply with the more stringent MCL or develop local MMM
program plans for approval by EPA.
The SDWA authorizes all States to develop and submit a MMM program
plan to mitigate radon levels in indoor air for approval by the
Administrator under Section 1412(b)(13)(G). EPA is proposing that
States that do not have primacy may submit a plan to EPA that meets the
criteria of 40 CFR 141.302. If the State's plan is approved, the State
would be subject to all reporting and compliance requirements of 40 CFR
141.303. Community water systems in States with approved MMM programs
would comply with the AMCL of 4000 pCi/L, and would be subject to the
requirements for monitoring and analytical methods in 40 CFR 141.20.
EPA would continue to administer compliance with the MCL/AMCL, and with
monitoring and methods requirements.

D. Implementation of the MMM Program in Indian Country

Under this proposal, States can develop State-wide MMM programs for
the reduction of radon in indoor air, and community water systems in
such States can then comply with an AMCL of 4000 pCi/L (rather than an
MCL of 300 pCi/L). Under Section 1451 of the SDWA, the Administrator of
EPA is authorized to treat Indian Tribes in the same manner as States.
The proposal provides tribes the option of seeking ``treatment in the
same manner as a State'' for the purposes of assuming enforcement
responsibility for a community water system program, and developing and
implementing an MMM program. If a tribe does not choose to implement an
MMM program, any tribal CWS may develop an MMM program plan for EPA
approval, under the same criteria described previously.
EPA is proposing to amend the ``treatment as a State'' regulations
to allow tribes to be treated in the same manner as States for purposes
of carrying out the MMM program. Under this proposal, a tribe would not
need to demonstrate that it qualified for treatment in the same manner
as a State for any other purpose other than the MMM provisions. Tribes
may want to seek treatment in the same manner as a State for this
limited purpose to the extent that radon is a significant problem on
tribal lands because the MMM program provides an opportunity to focus
resources on reducing the higher risk exposure--indoor air--and
addressing radon in drinking water at the highest levels of exposure.
EPA is proposing to amend the treatment in the same manner as State
regulations (40 CFR 142.72 and 40 CFR 142.78) to obtain treatment as a
State status solely for the purpose of implementing the MMM
authorities. Tribes can, of course, always apply to be treated in the
same manner as a State for primacy over the Public Water Supply Program
under 40 CFR 142.72.
A tribe applying for authority to develop and implement an MMM
program plan that has met the criteria under 40 CFR 142. 72 to be
treated in the same manner as a State for any purpose will not need to
reestablish that it meets the first two criteria (40 CFR 142.72 (a) and
(b)) and needs to provide only information in 40 CFR 142.76 that is
necessary to demonstrate that the criteria in 40 CFR 142.72 (c) and (d)
are met for the MMM program plan. A tribe whose application for
authority to carry out the MMM program is approved must develop and
implement a MMM program plan in accordance with 40 CFR 141.302 and
141.303.

E. CWS Role in State MMM Programs

EPA anticipates that CWSs, especially small systems, would have a
limited role in State-wide MMM programs. For example, States may
develop information brochures on radon that could be distributed
locally by CWSs. EPA expects that States will want to consult with
CWSs, small and large, in

[[Page 59261]]

making a determination about the nature and scope of the role, if any,
of CWSs in implementing a State-wide MMM program. During EPA's
stakeholder process, many States and CWSs agreed that States were best
positioned to design and implement effective State-wide MMM programs
and that it was not apparent what role CWSs might take in such a
program. However, CWSs do have important responsibilities for
communicating information on radon to their customers (see Section
VI.G).

F. Local CWS MMM Programs in Non-MMM States and State Role in Approval
of CWS MMM Program Plans

The regulatory expectation of small community public water systems
(CWSs) is that they meet the AMCL and be associated with a MMM program-
either developed by the State and approved by EPA or developed by the
CWS and approved by the State. EPA strongly recommends that States
choose to develop and implement State-wide MMM programs as the most
cost-effective approach to manage the health risks from radon. In those
cases where States do not elect to do a State-wide MMM program, CWSs
would need to notify the State of its intention to develop and submit a
local MMM program plan to the State (4 years after publication of the
final rule in the Federal Register). EPA believes that, in all cases,
the regulatory burden of complying with AMCL and implementing a MMM
program will be considerably less than complying with the more
stringent regulatory level for radon in drinking water. EPA believes
that the MMM/AMCL is the appropriate standard for CWSs, especially for
small systems, because it results in greater radon risk reduction and
makes better use of limited resources. EPA believes that the four
criteria for plan approval can be applied to CWS local MMM program
plans (as appropriate for the local level), commensurate with the
unique attributes of these CWSs and their service areas. As previously
discussed in more detail, these four criteria are: public
participation, setting quantitative goals, strategies for achieving
goals, and a plan to track and report results.
In general, EPA expects that CWSs would be able to meet the four
criteria by carrying out a wide range of diverse activities, many of
which are well within the expertise of CWSs. However, small CWSs would
not necessarily be expected to perform some of the activities entirely
on their own. In carrying out certain activities, small CWSs would be
expected to seek help from others in order to build upon and take
advantage of existing CWS and State networks. The existing State indoor
radon programs, for example, operate in large measure through a network
of State and local partners such as the American Lung Association, the
National Association of Counties, the National Environmental Health
Association, the National Safety Council, consumer advocacy groups,
non-government organizations, and other local and county governmental
organizations. CWSs should be able to use the same networks and their
capabilities, and State radon in indoor air programs should help
facilitate these contacts. The following provides some additional
perspective on the four criteria relative to CWS MMM programs.
Public Participation: Thorough public participation is certainly
within the capability of CWSs. Systems are often required in the course
of CWS activities, such as operation, maintenance, water bill
collection, violation notification, and planning for new facilities, to
involve, communicate with, inform, and in other ways interact with the
public. Thus, these systems already engage, to a significant degree, in
public outreach and communication. EPA expects that such expertise can
readily be directed toward the particular public participation
requirements associated with MMM programs. Public participating during
development of local MMM plans will help ensure greater local support
for and implementation of the CWS MMM programs.
Quantitative Goals: EPA notes that the quantitative goals that
CWSs, especially small CWSs, typically will need to establish may be
rather modest compared to those that would be expected for State-wide
programs. The level of risk reduction needed to ensure ``equal or
greater'' risk reduction be achieved (as if the MCL were being met)
from a local MMM program plan is a function of and takes into account
factors such as the size of the population served, level of radon in
drinking water, and most importantly, the needs and goals of the
community.
Strategies for Achieving Goals: EPA recognizes that promoting
public action in the areas of new homes built radon-resistant and
mitigation of existing homes with elevated levels of radon in indoor
air will be entirely new ventures for CWSs. However, EPA believes CWSs,
including small CWSs, will be capable of conducting various activities
designed to promote testing and mitigation of existing homes with
elevated levels of radon in indoor air and building of new homes to be
radon-resistant. Such activities include public education programs,
provision of radon test kits, establishing networks with local health
and government officials to gain their support and involvement in MMM
implementation, meeting with community leaders, customers, local real
estate and home building officials and organization, utilizing existing
information distribution network employed by CWSs, and other types of
activities to promote public action on indoor radon. EPA expects that
MMM program strategies for CWSs will be less comprehensive and far
reaching than those of State MMM programs, and will need to reflect the
local character of the community served by the CWS.
Tracking and Reporting of Results: EPA recognizes that assessing or
tracking progress towards meeting these goals also represents a new
responsibility for CWSs. However, CWSs may be able to build upon their
experience and networks for communicating with customers and
identifying their needs or concerns and find ways to collect
information about actions taking place in the community. To track homes
built or modified to be radon resistant, CWSs may be able to obtain
needed information from various local and State programs and offices
and other organizations in its network. CWS may also choose to employ
contractor support or consultant services to obtain this information or
to help track other MMM related activities. EPA also expects the States
to provide assistance to CWSs in developing their tracking and
assessment approach based on State experience in determining the
results of their State indoor radon programs. EPA recognizes that CWSs'
options for tracking results may be more limited than those available
to the States, and that States should consider such limitations in
their five-year review of local programs.
CWSs may find it useful to combine efforts with adjacent CWSs for
purpose of developing and implementing joint MMM programs, thereby
broadening their combined expertise, local infrastructure and
institutional bases, and network of partners. EPA also expects that
privately-owned, as well as publicly owned, CWSs can avail themselves
of these same kinds of networks, partnership, and consultant services.
Private systems will generally also be well connected to the municipal
entities in the jurisdictions in which they operate.
The report of the Small Business Advocacy Review Panel included a
discussion of the concept of a ``model MMM program'' for small systems
which would not be required but could

[[Page 59262]]

provide a workable option for small systems. It might address potential
concerns of the smallest systems that anticipate they may lack the
resources and expertise to develop an MMM program. As discussed
subsequently in Section VI. H., EPA has concerns in general about the
appropriateness and applicability of a ``one-size-fits-all'' approach
for MMM programs. A model approach, even for small CWSs, would not
address the unique, site-specific needs of different CWSs and their
associated communities. EPA is requesting public comment on the concept
of a model MMM program for CWSs.
As noted previously, EPA is strongly recommending that States
choose to develop and implement State-wide MMM programs as the most
cost-effective approach to manage the health risks from radon which
would preclude the need for water systems to develop such programs on
their own. EPA also believes the States which choose not to do an MMM
program have an important role, and are the best positioned, to assist
CWSs in development of local MMM program plans. EPA will also be
providing guidance to assist CWSs, including small CWSs, in the
development of local MMM programs. This section has discussed the
manner in which the four criteria could be applied to CWSs in non-MMM
States. EPA is requesting comment on approaches to applying these
criteria to CWSs, especially the smallest CWSs, in view of the
capabilities of these systems and their ability to get assistance from
others. EPA is also requesting comment on options that may be available
to CWSs, particularly, small systems, to develop and implement an MMM
program plan.
In summary, EPA recognizes that CWSs do not have the same
institutional base and infrastructure, legislative authority,
proportionate resource base, or indoor radon program experience as
States on which to base development of a local MMM program plan.
However, EPA believes that the four criteria for approval are equally
applicable to both States and CWSs, and can be applied to CWSs
(particularly small CWSs) in a manner that recognizes and accounts for
these differences. As discussed previously, the manner in which these
criteria are addressed by CWSs in local MMM program plans, and the
level and scope of effort, will necessarily differ from that embodied
in State plans. States should consider these differences in evaluating
CWS MMM program plans and in their five-year review of CWS MMM program
implementation. EPA believes that States, in particular, are best
positioned to assist CWSs, especially small systems, in the development
of local MMM programs that satisfy the four criteria, and expects them
to provide such assistance. In evaluating CWS plans, States should
exercise flexibility in their review and approval process, especially
for small CWSs, recognizing that they will not have the same
institutional and resource base or experience and may need to obtain
assistance from others.
The Agency expects that most systems in non-MMM States with radon
levels between 4,000 pCi/L and 300 pCi/L will develop and submit MMM
program plans. However, the Agency recognizes that some CWSs in non-MMM
States may elect not to develop a MMM program plan for a variety of
reasons. In these cases, certain options are available to small CWSs.
They may consider working with one or more other systems for the
purposes of developing and implementing an MMM program plan, in order
to take advantage of greater institutional capabilities. If a system
does not develop an MMM program plan on its own or together with other
systems, the system must comply with the MCL of 300 pCi/L through any
available means (e.g., blending, use of alternate sources, and
treatment).
From a risk communication standpoint, EPA wishes to convey to
customers of small CWSs that its regulatory expectation for these
systems is that they meet the AMCL and implement an MMM program.
However, CWSs can choose to meet the MCL rather than take the MMM
approach. If a CWS opts for the MMM/AMCL approach but is unable to
develop and successfully implement a State-approved MMM program plan,
it may be required as part of an enforcement order, to meet the MCL
rather than comply with the MMM/AMCL. The Agency requests comment on
this approach for small system MMM programs.
The SDWA provides that EPA will approve local water system MMM
program plans and EPA has developed the criteria to be used for
approving MMM program plans, as discussed in (A). EPA will review and
approve State MMM program plans. CWS MMM program plans that address the
criteria and are approved by the State are deemed approved by EPA. The
proposed rule requires States that do not have a State-wide MMM
program, as a condition of primacy for the radon regulation, to review
MMM program plans submitted by CWSs and to approve plans meeting the
four criteria for MMM program plans discussed in Section VI.A. of this,
including providing notice and opportunity for public comment on CWS
MMM program plans. EPA solicits comment on this approach to reviewing
and approving local MMM plans. Under SDWA, MMM program plans submitted
by CWSs are to be subject to the same criteria and conditions as State
MMM program plans. EPA believes that the States are best positioned to
assist CWSs, especially small systems, in the development and review of
local MMM program plans that meet the four criteria, and to have public
health oversight of the progress of the implementation of these local
radon risk reduction programs. EPA encourages those States not choosing
to develop a State-wide MMM program plan to exercise flexibility in
their review and approval of local MMM program plans, especially for
small CWSs, recognizing that CWSs will not have the same institutional
base, nor the State's program experience on indoor radon, on which to
base to local development of a MMM program plan. EPA expects that the
State drinking water programs and indoor radon programs will work
collaboratively in assisting CWSs that elect to develop and implement
local CWS MMM program plans and comply with the AMCL. In non-primacy
states, EPA will review and approve local CWS MMM program plans and
oversee compliance with the AMCL if the state chooses not to do a
state-wide MMM program plan. MMM program plans developed by Indian
Tribes or tribal community water systems will be reviewed by EPA. The
specific requirements of a CWS in a State with a State-wide MMM program
are addressed in Section VI.E. CWSs may choose to meet the MCL.
For those CWSs (both large and small) in non-MMM States that
develop local MMM program plans, the State would review the MMM program
at least once every 5 years and provide progress reports to the EPA in
keeping with the statutory requirements of the SDWA and this Section.
(States may also establish interim reporting requirements for the CWS
under a MMM program to help ensure adequate progress toward the goals
set forth in the local MMM program plan.) Failure of a CWS to develop
its MMM program plan by the required regulatory deadline or failure of
a CWS to implement its approved MMM program plan (5 years and 5\1/2\
years, respectively after the final rule is published) would be a
violation of this regulation unless the CWS is complying with the MCL.
It is expected that a CWS would be given time to correct any violations
relating to its MMM program

[[Page 59263]]

through an appropriate enforcement action.

G. CWS Role in Communicating to Customers

At a minimum, CWSs have important responsibilities for
communicating information on radon to their customers. Under the
requirements of the Consumer Confidence Rule (CCR), CWSs will be
required to provide key information on the health effects of radon
should the level of radon in drinking water exceed the MCL (or AMCL in
States with MMM programs). Today's action also updates the standard CCR
rule requirements and adds special requirements that reflect the
multimedia approach of this rule. The intent of these provisions is to
assist in clearer communication of the relative risks of radon in
indoor air from soil and from drinking water, and to encourage public
participation in the development of the State or CWS MMM program plans.
Today's action also proposes to require CWSs to add information to the
mandatory yearly report which would inform their customers on how to
get involved in developing their State or local CWS MMM program plan.
This information would include a brief educational statement on radon
risks, explaining that the principal radon risk comes from radon in
indoor air, rather than drinking water, and for that reason, radon risk
reduction efforts may be focused on indoor air rather than drinking
water. This information will also note that many States and systems are
in the process of creating programs to reduce exposure to radon, and
encourage readers to call for more information. This information would
be provided every year until the compliance date for implementation of
State MMM programs (or CWS local MMM programs in States without a
State-wide MMM program. (See Section X of this preamble for more
information on CCR and public notice requirements for radon). EPA is
also planning to develop public information materials on radon in
drinking water and indoor air as ``tools'' to assist CWSs, as well as
the States, Indian tribes, and others, with the risk communication
issues associated with the MCL, AMCL, and MMM.

H. How Did EPA Develop These Criteria?

EPA obtained extensive stakeholder input in developing the
regulatory criteria for State MMM program plans. Stakeholders
participating in this process represented many diverse groups and
organizations with an interest in radon, both from the perspective of
radon in drinking water and of radon in indoor air. This included State
drinking water and State radon program representatives, municipal and
privately owned public water system suppliers, local government
officials, environmental groups, and organizations representing State
health officials, county governments, public interest groups, and
others.
As part of the process of getting stakeholder input on development
of MMM guidelines and criteria, EPA presented several conceptual
framework options for MMM for discussion and consideration. Three
preliminary approaches were discussed: (1) To set specific numerical
targets in mitigations of existing houses and houses built radon-
resistant (as surrogates for lives saved) for each State to meet; (2)
to set a level of effort that States must demonstrate would be achieved
under their MMM plan; and (3) to set minimum core indoor radon program
elements required for all plans.
Under the first approach, specific targets to achieve ``equal''
risk reduction could be set using a variety of approaches and tools and
based on a number of factors, such as the level of radon in the
drinking water, the number of people served by that system, and other
factors. It would also require allocating among the States the total
number of lives saved nationally by universal compliance with the MCL
(estimated to be about 62 lives saved yearly). The allocation of lives
saved by States would likely lead to some State targets being fractions
of a life saved yearly, depending on the number of systems, radon
levels, and people served. Many stakeholders thought that significant
attention would need to be paid to the risk communication challenges of
communicating this approach to the public. Although some stakeholders
thought this approach might be workable, others did not consider it
universally applicable or workable and that it might preclude
flexibility and innovation.
The second approach, ``level of effort'', would focus more on a
plan for implementation of risk reduction strategies using a point
system where different risk reduction strategies (such as public
education, radon-resistant new construction code adoption, etc.) would
be assigned a specific number of points based on potential to achieve
health risk reduction. The number of State-specific points that a MMM
program plan would have to meet to be approved would require
determining the number of systems complying with the AMCL rather than
the MCL, the radon levels in their drinking water, and population
served. This approach would give States flexibility in choosing the
combination of indoor radon risk reduction strategies that best meets
the needs of that State by giving them a menu of approaches from
different categories of strategies with different assigned points.
There are two difficulties in implementing this approach that would
need to be addressed. First, it may be difficult to assign in advance a
specific quantified value for different strategies in terms of a
numerical outcome in risk reduction (i.e., in lives saved or in
existing homes mitigated or houses built radon-resistant). EPA
requested the National Academy of Sciences (NAS), as part of its
assessment of radon in drinking water, to ``prepare an assessment of
the health risk reduction benefits associated with various mitigation
measures [described in SDWA] to reduce radon levels in indoor air.''
Although the NAS included some review of the States' experience with
public education and risk communication, they did not include a
quantitative assessment of the ``health risk reduction benefits''
associated with specific ``mitigation measures'' referred to by SDWA.
Second, risk communication research has shown, and many stakeholders
agreed, that a variety of strategies must be employed simultaneously
when trying to get voluntary public actions on preventive health and
safety measures. It is often difficult to single out or characterize,
for example, the number of people who take voluntary health risk
reduction actions because of viewing a particular televised public
service announcement separate from other messages, activities,
communications, and efforts being implemented by society to reduce that
particular public health risk.
Setting specific State risk reduction targets or a level of effort
point system were considered in part to address language in the SDWA
radon provision that State plans approved by EPA are expected to
achieve health risk reduction benefits ``equal to or greater than the
health risk reduction benefits that would be achieved if each public
water system in the State complied with the maximum contaminant level
[MCL]* * *.'' As some stakeholders noted, there are complexities
associated with determining risk reduction targets (e.g., in pCi/L) for
indoor radon needed to substitute or ``make-up'' for some very small
level of risk reduction that would not occur if systems comply with the
AMCL. Careful attention would need to be paid to ensuring that this

[[Page 59264]]

approach did not produce the unintended effect of narrowly focusing or
limiting the risk reduction goals of MMM program plans. Some States and
other stakeholders were concerned that a complex approach, that may be
difficult to communicate to the public, could hamper voluntary public
action currently taking place on indoor radon. Some States thought that
they may have the data and/or tools that would permit such an approach.
The third conceptual approach was to require MMM program plans to
include a set of core program elements, without targets or points, to
be determined by EPA. This would require a set of basic program
elements that each State MMM program plan would have to incorporate to
be approved by EPA. In addition, the States could choose to add
additional program elements from a menu of strategies to be provided by
EPA. An example of implementation of a core program element might be
that each State would have to adopt radon-resistant new construction
standards into their State and local building codes, or require testing
and mitigation firms to register with the State and report numbers of
radon tests and mitigations conducted. Many stakeholders were concerned
that this approach might not provide sufficient flexibility needed by
the States to reflect their particular needs, including the scope of
the radon in drinking water and indoor radon problem, and the varying
extent to which the States have been addressing their indoor radon
problem through their existing State radon programs.
EPA is soliciting public comment on these three alternative
conceptual frameworks for MMM program plans that were examined through
the stakeholder process and is also requesting public comment on other
potential frameworks and rationale for why and how these would achieve
increased radon risk reduction.
While stakeholders had differing views of the three conceptual
approaches presented by EPA for discussion purposes, a number of mutual
concerns and issues integral to formulation of a conceptual framework
for MMM were identified. The following set of broad issues and concerns
raised by stakeholders were considered in the development of the
required criteria that EPA is proposing.
A uniform approach, that is, a ``one size fits all'' approach to
MMM might not provide States with the flexibility they need to custom
tailor their plans to their needs. Every State is different in terms of
the extent and magnitude of the indoor radon problem, the nature of the
existing State indoor radon program, the levels of radon in public
water supplies, and many other factors.
Because the SDWA framework for radon permits States to choose to
adopt either the MCL or AMCL/MMM option, some stakeholders believed
that States might be less inclined to adopt the MMM/AMCL approach if it
were considered too complex and difficult to implement and communicate
to the public. The approach needs to be simple and straightforward,
provide flexibility to accommodate the variety of needs in different
States, and encourage innovation at the State and local level.
MMM will be most effective if it is built on and consistent with
the foundation and infrastructure of the existing State indoor radon
programs. States are better positioned than public water suppliers to
achieve radon risk reduction under MMM programs. Most States currently
have a voluntary radon program. Some States noted the need for some
consistency between the criteria and objectives for MMM program plans
and the goals, priorities, and EPA's existing State Indoor Radon Grant
(SIRG) program guidance.
States and other stakeholders raised concerns about the potential
relationship between MMM and the current State indoor radon programs.
Stakeholders strongly encouraged EPA to carefully identify and consider
the potential for negative impacts of MMM requirements on current State
efforts on indoor radon. In particular there were concerns that
attention and resources might be diverted to the MMM program. States
might choose not to do a MMM program if the effectiveness or
infrastructure of their current indoor radon program might be reduced,
or if it does not help States meet the goals of their voluntary
programs. This would be counter-productive if it resulted in reduced
efforts and diminished infrastructure of a State's voluntary program
already achieving indoor radon risk reduction.
Some States felt it was important to have extensive public debate
and examination of any program proposed by the State in order to get
public support for the AMCL and MMM approach.
A number of stakeholders noted the need for MMM programs to have
definable endpoints or goals, show how these endpoints will be
attained, and describe how results will be determined. Some States
indicated the importance of demonstrating to the public that the
program is achieves radon risk reduction.
Stakeholders noted that the level of risk reduction that can be
achieved by focusing resources and effort on radon in indoor air is
significantly greater than what can be achieved by universal compliance
with the MCL. MCL-based risk reduction targets would also be
significantly smaller than the risk reduction already being achieved.
Therefore it is important to focus on the greater risk reduction
potential for radon in indoor air, and on enhancement of indoor radon
programs, rather than focus on the smaller risk reduction potential
from radon in water.
In developing and deciding on proposed criteria, EPA took into
account these stakeholder views and concerns, as well as EPA's goals
for MMM and the current approach used by EPA and the States to get
indoor radon risk reduction. This information and experience taken
together led to the proposed MMM criteria that are based upon three
elements: (1) Involve the public in development of MMM; (2) track the
level of indoor radon risk reduction that occurs; and, (3) build on the
existing framework of State indoor radon programs.
First, stakeholders suggested that extensive public participation
in the development of a State MMM program plan is important. One
important approach is to involve various segments of the public, from
community water system customers to key public health and other
organizations, the business community, local officials, and many
others. The public needs to be informed about and participate in the
MMM development process to ensure that the goals and other elements of
the plan will be publicly supported, responsive to the needs of the
various stakeholders, and meet public and State goals for reducing
indoor radon. Such a process may also result in increased public
awareness and voluntary action to reduce the levels of indoor radon.
Stakeholder involvement can help States clearly define goals and design
the process and strategies for meeting these goals. EPA recognizes that
there are a variety of non-quantitative and quantitative approaches,
tools, and types of information that can be used to develop goals, but
public input is very important to this process. The public involvement
in development and examination of plans will help to get support and
buy-in from all stakeholders to a set of goals, program strategies, and
results measurement, and thus, helps to ensure program success.
Second, a successful MMM program plan needs to include a provision
for determining progress on reducing the public's exposure to indoor
radon, and for reporting back to the public. In the case of indoor
radon, risk reduction results can be evaluated by tracking or

[[Page 59265]]

in some way determining the level of existing home mitigation and new
homes built radon-resistant. A few States already track this
information closely. Many do not. EPA believes that there are a variety
of approaches currently being used, such as statistically-based
surveys; State requirements for tracking testing and mitigation by
radon testing and mitigation companies; voluntary agreement by builders
to provide information on construction of radon-resistant homes; and
other approaches. EPA also recognizes the importance of providing
States the flexibility to craft new and innovative approaches for
tracking and assessing progress. Through implementation of a State-wide
MMM/AMCL approach, States may be able to provide new incentives and
opportunities for gathering the information the State will need to
demonstrate to the public, and EPA, that progress is being made in
getting public action to reduce radon risks.
Third, building MMM on the framework of existing State indoor radon
programs takes advantage of the existing programs already working to
get public action on indoor radon. Nearly every State currently has a
program with existing policies, public outreach and education programs,
partner networks and coalitions, and other infrastructure. States have
used the State Indoor Radon Grant (SIRG) funds available under Title
III of the Toxics Substances Control Act (TSCA) to develop a variety of
radon strategies, including distributing information materials to
educate the public, maintaining radon hotlines, conducting training
programs, providing technical assistance, operating certification
programs for the radon industry, setting up regulatory requirements for
industry reporting of testing and mitigation, conducting surveys
(testing) of homes and schools, working with local governments in high-
risk areas to establish incentive programs for radon-resistant new
construction, and many other activities. Many of these activities are
consistent with the findings of the National Academy of Sciences. They
found three factors were most important for motivating the public to
test and fix their home: (1) A radon awareness campaign; (2) promoting
the widespread voluntary testing by the public of indoor radon levels;
and (3) educating the public about mitigation and ensuring the
availability of qualified contractors. The reinforcement and
augmentation of these types of efforts through MMM programs is expected
to result in increased levels of testing and mitigation of existing
homes by the public and of homes being built to be radon-resistant.
The ``mitigation measures'' set forth in the 1996 SDWA are similar
to those being used in the existing national and State radon programs.
Section 1412 (b)(13)(G)(ii) provides that State MMM programs may rely
on a variety of ``mitigation measures'' including ``public education,
testing, training, technical assistance, remediation grants and loans
and incentive programs, or other regulatory or non-regulatory
measures''. These represent many of the same strategies that are
integral to the indoor radon program strategy, as well as those
outlined in the 1988 Indoor Radon Abatement Act.
The risk reduction achieved to date through the national and State
radon programs has been achieved primarily through a non-regulatory
approach. The SIRG guidance for implementing a program also outlines
and recommends indoor radon program priorities, encourages States to
develop narrative descriptions of how they intend to address the
priority areas, and encourages the establishment of goals for
awareness, testing and mitigation of homes and schools, and radon-
resistant new construction. Under SIRG, the States are required to
submit a list of their activities and workplans for each project that
will be done under the grant. While EPA's SIRG guidance requires a list
of program activities, it is not currently a Federal requirement under
the Indoor Radon Abatement Act of 1988 or under SIRG that State indoor
radon programs to: (a) publicly set goals for awareness, testing,
mitigation and new construction; (b) develop and implement a strategic
plan for action through real estate transactions, new home
construction, testing and fixing schools, and getting the public to
test and fix their homes; (c) develop and implement approaches to track
and measure the results of their strategic plans and activities and
report those results to the public; and (d) directly involve the public
in the development of the States' program goals and strategic plans.
EPA is proposing that, in order to have an approved MMM program plan,
States now be required to take these steps.
EPA believes this augmentation of State programs required under the
criteria will result in an increased level of risk reduction. States
will develop their plans with direct public participation in setting
goals, develop strategic plans in key areas, and develop approaches for
tracking and measuring results against goals. EPA also expects that
substantial and constructive public participation in the development
process of the State's MMM program plan is likely to result in a
program that meets the public's needs and concerns on an important
public health issue, as well as in greater public awareness of the
health effects of radon and in increased voluntary action by the public
to address their risks from indoor radon. Given EPA's estimate of the
expected increase in the yearly rate of lung cancer deaths avoided from
the current voluntary program, EPA expects that State MMM program plans
meeting these four criteria will achieve equal, or much more likely,
greater health risk reduction benefits.

I. Background on the Existing EPA and State Indoor Radon Programs

Implementation of EPA's current national strategy to reduce public
health risks from radon in indoor air has focused on using a
decentralized management and risk communication approach in partnership
with States, local governments and a network of national organizations;
a continuum of risk reduction strategies; and, a strong focus on key
priorities. Reduction of indoor radon levels has the potential to yield
very large risk reduction benefits through pursuit of a wide range of
approaches including the availability of relatively inexpensive
testing, mitigation, and new construction techniques to reduce the risk
from indoor radon. National, State, and local efforts continue to
proactively encourage the public to test and fix their homes, promote
action on radon in association with real estate transactions, and
promote the construction of new homes with radon-resistant techniques
through institutional changes such as local adoption of new
construction standards and codes.
Prior to 1985 the federal government and only a few States had
initiated activities to address indoor radon problems. The initial
foundation and scope of State programs was determined by the different
needs of the States. For example, some Western States developed
programs to assist citizens living on or near uranium mines or mill
tailings sites. When very high levels of radon in homes in the area
known as the Reading Prong in the Northeastern U.S. were discovered in
late 1984, the Agency began to develop and to implement a coordinated
national radon program. Some Eastern States situated over the Reading
Prong began to develop strong programs in response to homes being found
with radon levels in the hundreds and thousands of pCi/L of air.
However, there was no coordinated government program, or testing and

[[Page 59266]]

mitigation industry, to address the risks posed by radon and only a
very small fraction of the public was even aware of the problem.
Since then, there has been significant progress in the nation's
program to promote voluntary public action to reduce the health risks
from radon in indoor air. EPA's non-regulatory Radon Program has
established a partnership between federal, State, local and private
organizations, as well as private industry, working together on
numerous fronts to promote voluntary radon risk reduction. This
partnership initially focused programs on increasing public awareness
of the problem and providing the public with the necessary resources,
including a range of technical guidance and information, to enable them
to reduce their health risks through voluntary actions across the
nation. Congress endorsed this strategy and strengthened the indoor
radon program through the Superfund Amendments and Reauthorization Act
of 1986, and again in 1988 through passage of the Indoor Radon
Abatement Act. The Superfund Amendments and Reauthorization Act of 1986
(SARA) authorized EPA to conduct a national assessment of radon in
residences, schools, and workplaces. The 1988 Indoor Radon Abatement
Act (IRAA), an amendment to the Toxic Substances Control Act.
established the overall long-term goal of reducing indoor radon levels
to ambient outdoor levels, required the development and promotion of
model standards and techniques for radon-resistant construction, and
established the State Indoor Radon Grant program (SIRG). IRAA also
directed EPA to study radon levels in the U.S., evaluate mitigation
methods to reduce indoor radon, establish proficiency programs for
radon detection devices and services, develop training centers, provide
the public with information about radon, and assist States to develop
and implement programs to address indoor radon.
Recognizing the importance of working in partnership with the
States and leading national organizations, EPA developed a
decentralized system for informing the public about the health risks
from radon, consisting primarily of State and local governments and key
national organizations, with their state and local affiliates, who
serve as sources of radon information and support activities to the
public. EPA has worked with the States to help establish and enhance
effective State indoor radon programs and develop basic State
capabilities needed for assisting the public in reducing their risk
from indoor radon. EPA developed and transferred technical guidance on
radon measurement and mitigation to the States, the private sector, and
the public.
A key initiative in this effort to build State Radon Programs has
been the State Indoor Radon Grant (SIRG) Program, which provides
funding to help States develop and operate effective and self-
sustaining radon programs. As of August 1999, forty-five States are
currently participating in the SIRG program. These grants have been
instrumental in establishing State radon programs or in helping States
expand their radon programs more quickly than they otherwise could
have.
EPA, the States and national and local partners are using a mixture
of diverse strategies that range from the more flexible, such as
providing information to the public to encourage the public to act, to
more prescriptive, such as providing incentives that give some
advantage for taking action, or to adopting policies and requirements
that mandate certain actions. As a result, many initiatives are
underway today both to actively encourage and motivate homeowners to
test and fix their homes as well as to institutionalize risk reduction
through testing and mitigation during real estate transactions and
through construction of new homes to be radon-resistant.
EPA and the States, working with key national and local
organizations, have developed a wide range of channels for delivering
information to their members, affiliates and other target audiences.
Many organizations have their own ``hotlines,'' journals, brochures,
newsletters, press releases, radio and television programs, national
conferences, and offer training and continuing education programs.
These partners collaborate to urge public action on radon though a wide
variety of strategies including information, motivation, incentives,
and state and local mandates. The public receives a consistent message
on radon from EPA, the States, and a number of other key, respected,
and credible sources. Each target audience, like physicians or school
nurses or local government officials, becomes in turn a source of
information for new target audiences like their patients and local
constituents. This approach is comparable to that used to encourage
people to take various other voluntary preventive measures to reduce
their risk of various health and safety risks. Some of the national
organizations that EPA and the States work with include the American
Lung Association, the National Association of City and County Health
Officials, the National Parent Teacher Association, the Asian American
and Pacific County Health Officials, the Association of State and
Territorial Health Officials, the National Environmental Health
Association, the National Association of County Officials, the Consumer
Research Council of Consumer Federation of America, the National Safety
Council, and many others.
Many of the publicly available information materials are
specialized and designed to encourage specific actions by certain
groups, e.g., physicians, homebuilders, real estate agents, home
inspectors, home buyers and sellers, and many others. As a result, for
example, many home builders are voluntarily using radon resistant new
construction techniques and some real estate associations are
voluntarily incorporating the use of radon disclosure forms into their
regular business practices. Medical and health care professionals are
being educated about the health risks of radon and are encouraging
their patients to test their homes for radon as a preventive health
care measure. Public service announcements by local radio and TV
stations encourage the public to act. Other public information
materials provide consumers with information on how to test their homes
and what options they have for mitigating their radon problem.
Incentive programs and initiatives, such as free radon test kits,
and builder rebates when builders build homes radon-resistant, are
being implemented. States and local jurisdictions are also pursuing a
variety of regulatory radon initiatives, such as requiring schools to
be tested for indoor radon, requiring disclosure of elevated radon
levels in residential real estate transactions, and requiring new homes
to be built with radon-resistant new construction features through
building codes. These strategies and many others are being used to
successfully achieve public action to reduce the health risks from
indoor radon.
EPA has consulted with scientists, federal, state and local
government officials, public health organizations, risk communication
experts, and others to design this program and focus on radon program
strategies which have the greatest potential for reducing radon risks
through long-term institutional change. In developing strategies for
reducing radon risks, EPA and the States have learned from the
experience of other successful national public health campaigns, such
as the campaigns to promote the use of seat belts. These campaigns have
shown that significant public action to voluntarily

[[Page 59267]]

reduce health risks can be achieved from concerted efforts through a
variety of diverse strategies and through the combined efforts of State
and local governments, public health organizations, and other public
interest groups, grass roots organizations, and the private sector.
Program priorities have been identified to help concentrate and
focus efforts of EPA, the States, and local organizations, and others
on those activities that are most effective in achieving the overall
mission of indoor radon risk reduction. Working with a broad group of
stakeholders, EPA established several key priority areas for indoor
radon. States and cooperative national organizations have been focusing
many of their efforts and activities in these areas.
1. Targeting Efforts on the Greatest Risks First
EPA, the States, and many other public health organizations
recommend that all homes be tested and all homes at or above 4 pCi/L be
fixed. However, resources have been more heavily focused initially in
areas where action produces the most substantial risk reduction, such
as on homes and schools in the high radon potential areas and on the
increased risk of lung cancer from indoor radon to current and former
smokers.
2. Promote Radon-Resistant New Construction
EPA and others encourage programs to promote voluntary adoption of
radon-resistant building techniques by builders and the adoption of
radon construction standards into national, State and local building
codes. Methods (model standards) that establish construction techniques
for reducing radon entry in new construction have been developed and
published by EPA in collaboration with the National Association of Home
Builders. There are currently over 30 major building contractors (some
are national firms) who design and construct radon resistant new homes.
It is very cost-effective to build new homes radon-resistant,
especially in higher radon potential areas. In the existing indoor
radon program, EPA has been encouraging the States to promote testing
and mitigation in all areas of a State. EPA has also encouraged the
States to focus on their activities to promote radon-resistant new
construction on the highest radon potential areas (Zone 1) where
building homes radon-resistant is most cost-effective. However, it is
also cost-effective to build homes in medium potential areas (Zone 2),
as well as in ``hot'' spots found in most lower radon potential areas
(Zone 3).
3. Promote Testing and Mitigation During Real Estate Transactions
Based on the efforts of EPA, the States, and others, there has been
a steady increase in the number of radon tests and mitigations
voluntarily done through real estate actions. It is very cost-effective
to test and mitigate existing homes with elevated indoor radon levels.
Real estate transactions offer a significant opportunity to achieve
radon risk reduction. In 1993, EPA published the ``Home Buyer's and
Seller's Guide to Radon'' (USEPA 1993f). Hundreds of thousands of
copies of the ``Home Buyer's Guide'' have been distributed to
consumers. The companion to the ``Home Buyer's Guide'' is the
``Consumer's Guide to Radon Reduction'' (USEPA 1992d) which provides
information on how to go about reducing elevated radon levels in a
home.
A significant amount of radon testing and mitigation of existing
homes takes place during real estate transactions through the
combination of home inspections, real estate transfers, and relocation
services. Many different groups are in a position to influence buyers
and sellers to test and mitigate elevated radon levels. This includes
sales agents and brokers, buyers agents, home inspectors, mortgage
lenders, secondary mortgage lenders, appraisers, insurance companies,
State real estate licensing commissions, real estate educators,
relocation companies, real estate press, and others. There are
currently no requirements at the federal, State, or local level that a
house be tested for indoor radon as part of a real estate transaction.
Many State and local governments, however, have passed laws requiring
some form of radon disclosure, although the extent and detail of these
mandatory disclosure laws varies.
4. Promote Individual and Institutional Change through Public
Information and Outreach Programs
Because the health risk associated with indoor radon is controlled
primarily by individual citizens, EPA, the States and others have
developed a nationwide public information effort to inform the public
about the health risks from indoor radon and encourage them to take
action. EPA recommends that the public use EPA-listed or State-listed
radon test devices and hire a trained and qualified radon contractor to
fix elevated radon levels. Early on, EPA established voluntary programs
to evaluate the proficiency of these testing and mitigation service
companies to provide a mechanism for providing the public with
information by publishing updated lists of firms that pass all relevant
criteria. Many States have established their own proficiency programs.
To help support these efforts, EPA established four self-sustaining
Regional Radon Training Centers across the country to train testing and
mitigation contractors, State personnel, and others in radon
measurement, mitigation, and prevention techniques. In 1998, the
Conference of Radiation Control Program Directors (CRCPD), representing
State radiation officials, initiated a pilot program through the
National Environmental Health Association to establish a privatized
national proficiency program to replace EPA's proficiency program which
is terminating.

VII. What Are the Requirements for Addressing Radon in Water and
Radon in Air? MCL, AMCL and MMM

A CWS must monitor for radon in drinking water in accordance with
the regulations, as described in Section VIII of this preamble, and
report their results to the State. If the State determines that the
system is in compliance with the MCL of 300 pCi/L, the CWS does not
need to implement a MMM program (in the absence of a State program),
but must continue to monitor as required.
As discussed in Section VI, EPA anticipates that most States will
choose to develop a State-wide MMM program as the most cost-effective
approach to radon risk reduction. In this case, all CWSs within the
State may comply with the AMCL of 4000 pCi/L. Thus, EPA expects the
vast majority of CWSs will be subject only to the AMCL. In those
instances where the State does not adopt this approach, the proposed
regulation provides the following requirements:

A. Requirements for Small Systems Serving 10,000 People or Less

The EPA is proposing that small CWS serving 10,000 people or less
must comply with the AMCL, and implement a MMM program (if there is no
state MMM program). This is the cut-off level specified by Congress in
the 1996 Amendments to the Safe Drinking Water Act for small system
flexibility provisions. Because this definition does not correspond to
the definitions of ``small'' for small businesses, governments, and
non-profit organizations previously established under the RFA, EPA
requested comment on an alternative definition of ``small entity'' in
the preamble to the proposed

[[Page 59268]]

Consumer Confidence Report (CCR) regulation (63 FR 7620, February 13,
1998). Comments showed that stakeholders support the proposed
alternative definition. EPA also consulted with the SBA Office of
Advocacy on the definition as it relates to small business analysis. In
the preamble to the final CCR regulation (63 FR 4511, August 19, 1998),
EPA stated its intent to establish this alternative definition for
regulatory flexibility assessments under the RFA for all drinking water
regulations and has thus used it for this radon in drinking water
rulemaking. Further information supporting this certification is
available in the public docket for this rule.
EPA's regulation expectation for small CWSs is the MMM and AMCL
because this approach is a much more cost-effective way to reduce radon
risk than compliance with the MCL. (While EPA believes that the MMM
approach is preferable for small systems in a non-MMM State, they may,
at their discretion, choose the option of meeting the MCL of 300 pCi/L
instead of developing a local MMM program). The CWSs will be required
to submit MMM program plans to their State for approval. (See Sections
VI.A and F for further discussion of this approach).
SDWA Section 1412(b)(13)(E) directs EPA to take into account the
costs and benefits of programs to reduce radon in indoor air when
setting the MCL. In this regard, the Agency expects that implementation
of a MMM program and CWS compliance with 4000 pCi/L will provide
greater risk reduction for indoor radon at costs more proportionate to
the benefits and commensurate with the resources of small CWSs. It is
EPA's intent to minimize economic impacts on a significant number of
small CWSs, while providing increased public health protection by
emphasizing the more cost-effective multimedia approach for radon risk
reduction.

B. Requirements for Large Systems Serving More Than 10,000 People

The proposal requires large community water systems, those serving
populations greater than 10,000, to comply with the MCL of 300 pCi/L
unless the State develops a State-wide MMM program, or the CWSs
develops and implements a MMM program meeting the four regulatory
requirements, in which case large systems may comply with the AMCL of
4,000 pCi/L. CWSs developing their own MMM plans will be required to
submit these plans to their State for approval.

C. State Role in Approval of CWS MMM Program Plans

The SDWA provides that EPA will approve CWS MMM program plans. EPA
has developed criteria to be used for approving MMM programs. EPA will
review and approve State MMM program plans. CWS MMM program plans that
address the criteria and are approved by the State are deemed approved
by EPA. The proposed rule requires States that do not have a State-wide
MMM program, as a condition of primacy for the radon regulation, to
review MMM program plans submitted by CWSs and to approve plans meeting
the four criteria for MMM programs discussed in Section VI of this
preamble, including providing notice and opportunity for public comment
on CWS MMM program plans. Under Section 1412(b)(13)(G)(vi) of SDWA, MMM
program plans submitted by CWSs are to be subject to the same criteria
and conditions as State MMM program plans. EPA will review CWS MMM
program plans in non-primacy States, Tribes and Territories that do not
have a state-wide MMM program, and approve them if they meet the four
required criteria.

D. Background on Selection of MCL and AMCL

The SDWA directs that if the MCL for radon is set at a level more
stringent than the level in drinking water that would correspond to the
average concentration of radon in outdoor air, EPA must also set an
alternative MCL at the level corresponding to the average concentration
in outdoor air. Consistent with this requirement, EPA is proposing to
set the AMCL at 4000 pCi/L. This level is based on technical and
scientific guidance contained in the NAS Report (NAS 1999b) on the
water-to-air transfer factor of 10,000 pCi/L in water to 1 pCi/L in
indoor air and the average outdoor radon level of 0.4 pCi/L.
The SDWA generally requires that EPA set the MCL for each
contaminant as close as feasible to the MCLG, based on available
technology and taking costs to large systems into account. The 1996
amendments to the SDWA added the requirement that the Administrator
determine whether or not the benefits of a proposed maximum contaminant
level justify the costs based on the HRRCA required under Section
1412(b)(3)(C). They also provide new discretionary authority to the
Administrator to set an MCL less stringent than the feasible level if
the benefits of an MCL set at the feasible level would not justify the
costs (SDWA section 1412(b)(6)(A)).
EPA is proposing to set the MCL at 300 pCi/L, in consideration of
several factors. First, the Agency considered the general statutory
requirement that the MCL be set as close as feasible to the MCLG of
zero (SDWA section 1412(b)(4)), and its responsibility to protect
public health. In addition, the radon-specific provisions of the
amendments provide that, in promulgating a radon standard, the Agency
take into account the costs and benefits of programs to control indoor
radon (SDWA 1412(b)(13)(E). Although EPA believes that an MCL of 100
pCi/L would be feasible, EPA believes that consideration of the costs
and benefits of indoor radon control programs allows the level of the
MCL to be adjusted to a less stringent level than the Agency would set
using the SDWA feasibility test. The proposed MCL of 300 pCi/L takes
into account and relies on the unique conditions of this provision and
the reality it reflects that the great preponderance of radon risk is
in air, not water, and the much more cost-effective alternative to
water treatment is to address radon in indoor air through the MMM
program. The Agency recognizes that controlling radon in air will
substantially reduce human health risk in more cost-effective ways than
spending resources to control radon in drinking water. If most states
adopted the MMM/AMCL option, EPA estimates the combined costs for
treatment of water at systems exceeding the AMCL, developing a MMM
program, and implementing measures to get risk reduction equivalent to
national compliance with the MCL (62 avoided fatal cancer cases and 4
avoided non-fatal cancer cases per year) at $80 million, which is
substantially less than the $407.6 million cost of achieving the MCL.
EPA expects that most states will adopt the AMCL/MMM program option
While EPA believes it is appropriate to acknowledge the more cost-
effective control program to a certain extent in setting the MCL, the
Agency does not believe the cost-effectiveness is the sole determining
factor. Rather, EPA believes the absolute level of risk to which
members of the public may be exposed is also a key consideration in
determining a standard that is protective of public health.
The Agency proposed an MCL of 300 pCi/L in 1991 based, in part, on
its assessment of the health risk posed by radon in drinking water. It
should be noted that the overall magnitude of risk estimated by the
Agency at that time is in agreement with the overall risk of radon in
drinking water currently estimated by the National Academy of Sciences
(NAS 1999b). The Agency has

[[Page 59269]]

a long-standing policy that drinking water standards should limit risk
to within a range of approximately 10 ^-4 to 10 ^-6
and is thus proposing to use the flexibility provided by the authority
in 1412(b)(13)(E) to propose an MCL of 300 pCi/L, which is
approximately at the upper bound of the Agency's traditional risk range
used for the drinking water program (representing an estimated 2 fatal
cancers per 10,000 persons).
As noted earlier, the Administrator must publish a determination as
to whether the benefits of the proposed MCL justify the costs, based on
the Health Risk Reduction and Cost Analysis prepared in accordance with
SDWA Sec. 1412(b)(3)(C). Accordingly, the Administrator has determined
that the benefits of the proposed MCL of 300 pCi/L justify the costs.
The benefits of the proposed MCL, include about 62 avoided fatal lung
cancer cases and 4 avoided non-fatal lung cancer cases annually. EPA
has used a valuation of $5.8 million ($1997) to value the avoided fatal
cancers and a valuation of $536,000 ($1997) to value the avoided non-
fatal cancers. Multiplying these valuations by the estimated cancer
cases avoided (62 fatal, 3.6 non-fatal) yields a benefits estimate of
$362 million per year. The cost to achieve national compliance with an
MCL of 300 pCi/L is estimated at $407.6 million per year. EPA expects
the actual cost of the proposed rule to be significantly lower, since
the expectation is that most systems will not need to comply with the
MCL of 300 pCi/L. Costs would be about $80 million per year if the
AMCL/MMM option is widely adopted by States.
There are also some potential non-quantified benefits, including
customer peace of mind from knowing drinking water has been treated for
radon and reduced treatment costs for arsenic for some water systems
that have problems with both contaminants, and non-quantified costs,
including increased risks from exposure to disinfection byproducts,
permitting and treatment of radon off-gassing, anxiety on the part of
residents near treatment plants and customers who may not have
previously been aware of radon in their water, and safety measures
necessary to protect treatment plant personnel from exposure to
radiation. However, in this case it is not likely that accounting for
these non-quantifiable benefits and costs quantitatively would
significantly alter the overall assessment. Taking both quantified and
non-quantified benefits into account, EPA has determined that the costs
are justified by the benefits. Accordingly, the new authority to set a
less stringent MCL if benefits do not justify costs is not applicable
and has not been used in this proposal.
Although the central tendency estimate of monetized costs exceeds
the central tendency estimate of monetized benefits, the determination
that benefits justify costs is consistent with the legislative history
of this provision, which makes clear that this determination whether
benefits ``justify'' costs is more than a simple arithmetic analysis of
whether benefits ``exceed'' or ``outweigh'' costs. The determination
must also ``reflect the non-quantifiable nature of some of the benefits
and costs that may be considered. The Administrator is not required to
demonstrate that the dollar value of the benefits are greater (or
lesser) than the dollar value of the costs.'' [Senate Report 104-169 on
S. 1316, p. 33] The determination is based on the analysis conducted
under SDWA Sec. 1412(b)(3)(C), in the Health Risk Reduction and Cost
Analysis (HRRCA) published for public comment on February 26, 1999 (64
FR 9559), revised in response to public comment, and available as part
of the Regulatory Impact Analysis (1999n) in the public docket to
support this rulemaking. The costs and benefits of the proposed rule,
and the methodologies used to calculate them, are discussed in detail
in section XII of this preamble and in the Regulatory Impact Analysis
(1999n).
In making this determination, EPA also considered the special
nature of the radon standard, which provides an alternate MCL of 4000
pCi/L for states or water systems that adopt a MMM program designed to
produce equal or greater risk reduction benefits to compliance with the
MCL by promoting voluntary public action to mitigate radon in indoor
air. As noted previously, mitigation of radon in indoor air is much
more cost-effective than mitigation of radon in drinking water. If most
states adopted the MMM/AMCL option, EPA estimates the combined costs
for treatment of water at systems exceeding the AMCL, developing a MMM
program, and implementing measures to get risk reduction equivalent to
national compliance with the MCL (62 avoided fatal cancer cases and 4
avoided non-fatal cancer cases per year) at $80 million, which is
substantially less than the $407.6 million cost of achieving the MCL.
In its valuation of costs and benefits for the MMM program, EPA has
assumed that adopting the MMM approach will achieve only benefits
equivalent to those for meeting the MCL and has calculated the costs
and benefits of the proposed rule on this basis. However, EPA expects
that adoption of MMM programs will be widespread as a result of this
rule and that the actual benefits realized will be far greater than
those associated with meeting the MCL. In addition, EPA fully expects
most States to follow the MMM approach, therefore CWSs below the AMCL
will incur minimal costs and a much smaller subset of CWSs will incur
costs to meet the AMCL. Thus, costs for meeting the MCL are a
theoretical worst case scenario which the Agency believes will not
occur, particularly since the regulatory expectation for water systems
serving 10,000 people or fewer would be that they meet the 4000 pCi/L
AMCL, along with implementation of a local MMM program. Although in
some cases small CWSs may choose to meet the MCL of 300 pCi/L through
water treatment, this is voluntary and not a requirement of the
proposed regulation.
The Agency also considered the costs, benefits, and risk reduction
potential of radon levels at 100 pCi/l, 500 pCi/L, 1000 pCi/L, 2000
pCi/L and 4000 pCi/L. As table VII.1 illustrates, the costs and
benefits increase as the radon level increases. The quantified costs
somewhat exceed the quantified benefits at each level, but the benefit-
cost ratios are similar. However, the difference between costs and
benefits becomes somewhat larger as the various MCL options become more
stringent, with the largest difference at 100 pCi/L. When the
uncertainty of the estimates is factored in, there is overlap in the
benefit and cost estimates at all evaluated options. For more
information on this analysis, please refer to the Regulatory Impact
Analysis (RIA) for this proposal (USEPA, 1999n).

[[Page 59270]]

Table VII.1.--Evaluation of Radon Levels
--------------------------------------------------------------------------------------------------------------------------------------------------------
Cost per
Fatal fatal Total Monetized
Radon level (pCi/L) cancer Individual fatal lifetime cancer risk cancer case national benefits \1\ Benefit-
cases avoided costs \1\ $M cost ratio
avoided ($M) $M
--------------------------------------------------------------------------------------------------------------------------------------------------------
4000....................................... 2.9 26.8 in 10,000........................... 14.9 43.1 17.0 0.4
2000....................................... 7.3 13.4 in 10,000........................... 9.5 69.7 42.7 0.6
1000....................................... 17.8 6.7 in 10,000............................ 7.3 130.5 103 0.8
500........................................ 37.6 3.35 in 10,000........................... 6.8 257.4 219 0.9
300........................................ 62.0 2.0 in 10,000............................ 6.6 407.6 362 0.9
100........................................ 120.0 0.67 in 10,000........................... 6.8 816.2 702 0.9
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Water Mitigation only; assuming 100% compliance with MCL. Source: revised HRRCA.

Some commenters recommended that EPA give serious consideration to
setting an MCL at the AMCL level (4000 pCi/L), or at least at a level
substantially above 300 pCi/L, in order to control radon levels in
drinking water at a level more comparable to outdoor background levels.
This approach was also discussed by the Small Business Advocacy Review
Panel convened for this rule under the RFA as amended by SBREFA. (A
copy of the Panel's final report is available in the docket for this
rule making, (USEPA, 1998c).)
As noted earlier, EPA's interpretation of the standard-setting
requirements of the SDWA for radon are that they rely primarily upon
the general standard-setting provisions for National Primary Drinking
Water Regulations, with some additional radon-specific provisions. The
general provisions require that the MCL be set as close as feasible to
the MCLG. The radon-specific provisions direct the Administrator to
take into account the costs and benefits of control programs for radon
from other sources. As discussed, EPA is interpreting these general and
radon-specific authorities to propose an MCL above the feasible level,
near the upper end of the risk range traditionally used by the Agency
in setting drinking water standards. In addition, EPA believes that the
extensive statutory detail enacted on multimedia mitigation illustrates
a congressional preference for cost-effective compliance through the
AMCL/MMM program approach. EPA notes that the equal or greater risk
reduction required to be achieved through the AMCL/MMM option would be
diminished as the MCL approaches the AMCL of 4,000 pCi/L and that fewer
States and CWSs would select this option. Further, the AMCL/MMM
approach would be eliminated entirely if the MCL were set at the AMCL.
As noted previously, EPA believes the proposed MCL of 300 pCi/L, in
combination with the proposed AMCL and MMM approach, accurately and
fully reflects the SDWA provisions. The Agency recognizes , however,
that some stakeholders may have strong views about the appropriateness
of setting an MCL at a higher level. Accordingly, EPA requests comment
on the option of setting the MCL closer to or at the AMCL level of 4000
pCi/L. In this connection, the Agency also requests comments on and the
rationale for how such alternative options could be legally supported
under the SDWA and in the record for this rulemaking, in light of the
considerations EPA has applied for the MCL it proposes.
EPA solicits comment on the proposed MCL and AMCL and the Agency's
rationale, and on other appropriate MCLs given these considerations,
and the rationale for alternative levels. In the final rule, the Agency
may select a higher or lower option from those analyzed in the HRRCA
for the final radon rule without further public comment.

E. Compliance Dates

The proposed time line for compliance with the radon rule is
described next and illustrated in Figure VII.1.

BILLING CODE 6560-60-P

[[Page 59271]]

[GRAPHIC] [TIFF OMITTED] TP02NO99.002

BILLING CODE 6560-50-C

[[Page 59272]]

States are required to submit their primacy revision application
packages by two years from the date of publication of the final rule in
the Federal Register. For States adopting the AMCL, EPA approval of a
State's primacy revision application is contingent on submission of and
EPA approval of the State's MMM program plan. Therefore, EPA is
proposing to require submission of State-wide MMM program plans as part
of the complete and final primacy revision application. This will
enable EPA to review and approve the complete primacy application in a
timely and efficient manner in order to provide States with as much
time as possible to begin to implement MMM programs. In accordance with
Section 1413(b)(1) of SDWA and 40 CFR 142.12(d)(3), EPA is to review
primacy applications within 90 days. Therefore, although the SDWA
allows 180 days for EPA review and approval of MMM program plans, EPA
expects to review and approve State primacy revision applications for
the AMCL, including the State-wide MMM program plan, within 90 days of
submission to EPA.
EPA is proposing that CWSs begin their initial monitoring
requirements (one year of quarterly monitoring) for radon by 3 years
after publication of the final rule in the Federal Register, except for
CWSs in States that submit a letter to the Administrator committing to
develop an MMM program plan in accordance with Section 1412
(b)(13)(G)(v). For CWSs in these States, one year of quarterly
monitoring is proposed to begin 4.5 years after publication of the
final rule. The proposed rule allows systems to use grandfathered data
collected after the proposal date to satisfy the initial monitoring
requirements provided the monitoring and analytical methods employed
satisfy the regulations set forth in the rule and the State approves.
Systems opting to conduct early monitoring will not be considered in
violation of the MCL/AMCL until after the initial monitoring period
applicable to their State (i.e., 4 years after publication of the final
rule, 5.5 years after publication of the final rule).
The routine and reduced monitoring requirements were developed to
be consistent with the Standardized Monitoring Framework (SMF) and the
Phase II/V monitoring schedule. EPA believes this is valuable for
States and systems by providing sampling efficiency and organization,
therefore, EPA has tried to adapt the compliance dates so that States
and systems can make a smooth transition into the SMF following the
initial monitoring requirements. The necessity to complete the initial
monitoring in a timely manner is driven by the need for systems in non-
MMM States to evaluate their compliance options, including development
of a local MMM program and compliance with the AMCL), and for systems
in MMM States to ensure compliance with the AMCL.
EPA feels it is important to set time constraints on implementation
of the MMM plans to ensure the equal or greater risk reduction
resulting from multimedia mitigation. Therefore, the rule must allow
the systems in non-MMM States enough time to develop their MMM program
plan with technical assistance from the State and submit the plan for
State approval. In addition, the State must have sufficient time to
review and approve the local plans. If the compliance determination for
a system in a non-MMM State exceeds the MCL during the initial
monitoring period, the proposed rule requires these systems to notify
the State of their intention to develop a local MMM program at the
completion of initial monitoring, 4 years after publication of the
final rule. The local MMM program plans must be submitted to the State
for approval by 5 years after of publication of the final rule (i.e.,
12 months after the completion of initial monitoring) and the States
have 6 months from the submittal date to review and approve or
disapprove the plan. The system will begin implementation of their MMM
program 5.5 years after publication of the final rule (i.e., 1.5 years
after the completion of initial monitoring). If the State fails to
review and disapprove the local MMM program in the time allowed, the
system will begin implementation of the submitted plan. If the system
fails to comply with these compliance dates, a MCL violation will apply
from the date of exceedence. If the compliance determination for a
system choosing to comply with the MCL exceeds the MCL following the
completion of the initial monitoring period, the system will have the
option to submit a local MMM plan to the State within 1 year from the
date of the exceedence and begin implementation 1.5 years from the date
of the exceedence or incur a MCL violation.
Implementation of State-wide MMM programs must begin 3 years after
publication of the final rule, unless the State submits a letter to the
Administrator committing to develop an MMM program plan in accordance
with Section 1412 (b)(13)(G)(v) of the SDWA. States submitting this
letter must implement their State-wide MMM program plan by 4.5 years
after publication of the final rule. EPA feels it is extremely
important that the MMM program plans be completed on a schedule that
allows States sufficient time to begin implementation by the compliance
date to ensure that equal or greater risk reduction benefits are
provided.
EPA recognizes potential issues may arise as a result of the
proposed initial monitoring schedule. The potential issues include lab
capacity and a temporary deviation from the SMF schedule. EPA is
requesting comment on alternatives to avoid or lessen the impact of
these issues and other issues not listed here.
EPA considers the proposed monitoring schedule to be acceptable
since the proposed rule affects one contaminant and applies to a
smaller universe of water systems (NTNCWSs, transient systems, and CWSs
relying solely on surface water are not covered by the rule) which
decreases the number of systems effected, and therefore lessens the
impacts of the potential issues. An alternative initial monitoring
scenario which was considered would specify early monitoring
requirements for systems serving more than 10,000 people. This scenario
would put additional burden on the States and systems to monitor early
and it would not substantially ease the workload since the number of
systems serving greater than 10,000 that use groundwater or groundwater
under the direct influence of surface water is relatively small.
Initial monitoring could be phased in over a period of two or three
years, but EPA does not feel it is appropriate to extend the initial
monitoring period due to the necessity to evaluate the need to develop
and implement local MMM program plans. In MMM States, systems must be
in compliance with the AMCL in a timely manner to ensure the maximum
risk reduction.
In consideration of all these factors, EPA is proposing to require
the initial monitoring over a one-year period as specified earlier.
However, systems opting to conduct early monitoring will not be
considered in violation of the MCL/AMCL until after the initial
monitoring period applicable to their State (i.e., 4 years after
publication of the final rule, 5.5 years after publication of the final
rule). However, CWSs opting to conduct early monitoring will not be
considered in violation of the MCL/AMCL until after the initial
monitoring period applicable to their State (i.e., 4 years after
publication of the final rule, 5.5 years after publication of the final
rule. It is EPA's strong recommendation that all States choose to adopt
the AMCL and implement an MMM

[[Page 59273]]

program. But some States may elect to adopt the MCL or may decide later
to adopt the AMCL/MMM approach. In these states, the initial monitoring
will be required to begin by 3 years after publication of the final
rule, whereas in States submitting the 90-day letter committing to
develop an MMM program plan will begin initial monitoring 4.5 years
after publication of the final rule.

VIII. What Are the Requirements for Testing for and Treating Radon
in Drinking Water?

A. Best Available Technologies (BATs), Small Systems Compliance
Technologies (SSCTs), and Associated Costs

1. Background
Section 1412(b)(4)(E) of the Act states that each national primary
drinking water regulation which establishes an MCL shall list the
technology, treatment techniques, and other means which the
Administrator finds to be feasible for purposes of meeting the MCL. In
addition, the Act states that EPA shall list, if possible, affordable
small systems compliance technologies (SSCTs) that are feasible for the
purposes of meeting the MCL. In order to fulfill these requirements,
EPA has identified best available technologies (BAT) and SSCTs for
radon.
(a) Proposed BAT. Technologies are judged to be BAT when they are
able to satisfactorily meet the criteria of being capable of high
removal efficiency; having general geographic applicability, reasonable
cost, and a reasonable service life; being compatible with other water
treatment processes; and demonstrating the ability to bring all of the
water in a system into compliance. The Agency proposes that, of the
technologies capable of removing radon from source water, only aeration
fulfills these requirements of the SDWA for BAT determinations for this
contaminant. The full range of technical capabilities for this proposed
BAT is discussed in the EPA Technologies and Costs document for radon
(USEPA 1999h). Table VIII.A.1 summarizes the BAT findings by EPA for
the removal of the subject drinking water contaminants, including a
summary of removal capabilities.

Table VIII.A.1--Proposed Bat and Associated Contaminant Removal
Efficiencies
------------------------------------------------------------------------

------------------------------------------------------------------------
High Performance Aeration \1\............ Up to 99.9% Removal.
------------------------------------------------------------------------
Note: (1) High Performance Aeration is defined as the group of aeration
technologies that are capable of being designed for high radon removal
efficiencies, i.e., Packed Tower Aeration, Multi-Stage Bubble Aeration
and other suitable diffused bubble aeration technologies, Shallow Tray
and other suitable Tray Aeration technologies, and any other aeration
technologies that are capable of similar high performance.

Granular activated carbon (GAC) can also remove radon from water,
and was evaluated as a potential BAT and a potential small systems
compliance technology for radon. Since GAC removes radon less
efficiently than it does organic contaminants, it generally requires
designs that use larger quantities of carbon per volume of water
treated to remove radon compared to contaminants for which GAC is BAT.
This requirement for larger carbon amounts translates to much higher
treatment costs for GAC radon removal. In fact, full-scale application
of GAC for radon removal has been limited to installations at the
household point-of-entry and for centralized treatment for very small
communities (AWWARF 1998a). EPA has determined that the requirements
for radon removal render it infeasible for large municipal treatment
systems, and it is therefore not considered a BAT for radon. However,
GAC and point-of-entry (POE) GAC may be appropriate for very small
systems under some circumstances, as described next (USEPA 1999h,
AWWARF 1998a, AWWARF 1998b).
(b) Proposed Small Systems Compliance Technologies. The 1996
Amendments to SDWA recognize that BAT determinations may not address
many of the problems faced by small systems. In response to this
concern, the Act specifically requires EPA to make technology
assessments relevant to the three categories of small systems
respectively for both existing and future regulations. These
requirements are in addition to EPA's obligation, unchanged by the SDWA
as amended in 1996, to designate BAT. The three population-served size
categories of small systems defined by the 1996 SDWA are: 10,000--3,301
persons, 3,300--501 persons, and 500--25 persons. These evaluations
include assessments of affordability and technical feasibility of
treatment technologies for each class of small system. Table VIII.A.2,
``Proposed Small Systems Compliance Technologies (SSCTs) and Associated
Contaminant Removal Efficiencies'', lists the proposed small systems
compliance technologies for radon and summarizes EPA's findings
regarding affordability and technical feasibility for the evaluated
technologies. EPA has interpreted the SSCTs as equivalent to BATs under
Section 1415 of the Act, for the purposes of small systems (those
serving 10,000 persons or fewer) applying to primacy agencies for
Section 1415(a) variances.

Table VIII.A.2.-- Proposed Small Systems Compliance Technologies (SSCTS) \1\ and Associated Contaminant Removal
Efficiencies
----------------------------------------------------------------------------------------------------------------
Affordable listed Limitations
Small systems compliance small systems Removal efficiency Operator level (see
technology categories \2\ required \3\ footnotes)
----------------------------------------------------------------------------------------------------------------
Packed Tower Aeration (PTA)..... All Size Categories 90- > 99.9% Removal Intermediate........ ^(a)
High Performance Package Plant All Size Categories 90- > 99.9% Removal Basic to ^(a)
Aeration (e.g., Multi-Stage Intermediate.
Bubble Aeration, Shallow Tray
Aeration).
Diffused Bubble Aeration........ All Size Categories 70 to > 99% removal Basic............... ^(a, ^b)
Tray Aeration................... All Size Categories 80 to > 90%........ Basic............... ^(a, ^c)
Spray Aeration.................. All Size Categories 80 to > 90%........ Basic............... ^(a, ^d)
Mechanical Surface Aeration..... All Size Categories > 90%.............. Basic............... ^(a, ^e)
Centralized granular activated May not be 50 to > 99% Removal Basic............... ^(f)
carbon. affordable, except
for very small
flows.

[[Page 59274]]

Point-of-Entry (POE) granular May be affordable 50 to > 99% Removal Basic............... ^(f, ^g)
activated carbon. for systems
serving fewer than
500 persons..
----------------------------------------------------------------------------------------------------------------
Notes: \1\ The Act (Section 1412(b)(4)(E)(ii)) specifies that SSCTs must be affordable and technically feasible
for small systems.
\2\ This section specifies three categories of small systems: (i) those serving 25 or more, but fewer than 501,
(ii) those serving more than 500, but fewer than 3,301, and (iii) those serving more than 3,300, but fewer
than 10,001.
\3\ From National Research Council. Safe Water from Every Tap: Improving Water Service to Small Communities.
National Academy Press. Washington, DC. 1997.
Limitations: ^(a) Pre-treatment to inhibit fouling may be needed. Post-treatment disinfection and/or corrosion
control may be needed.
^(b) May not be as efficient as other aeration technologies because it does not provide for convective movement
of the water, which reduces the air:water contact. It is generally used in adaptation to existing basins.
^(c) Costs may increase if a forced draft is used. Slime and algae growth can be a problem, but may be controlled
with chemicals, e.g., copper sulfate or chlorine.
^(d) In single pass mode, may be limited to uses where low removals are required. In multiple pass mode (or with
multiple compartments), higher removals may be achieved.
^(e) May be most applicable for low removals, since long detention times, high energy consumption, and large
basins may be required for larger removal efficiencies.
^(f) Applicability may be restricted to radon influent levels below around 5000 pCi/L to reduce risk of the build-
up of radioactive radon progeny. Carbon bed disposal frequency should be designed to allow for standard
disposal practices. If disposal frequency is too long, radon progeny, radium, and/or uranium build-up may make
disposal costs prohibitive. Proper shielding may be required to reduce gamma emissions from the GAC unit. GAC
may be cost-prohibitive except for very small flows.
^(g) When POE devices are used for compliance, programs to ensure proper long-term operation, maintenance, and
monitoring must be provided by the water system to ensure adequate performance.

(c) Approaches for Listing Small Systems Compliance Technologies
(SSCTs). EPA has considered several options for the listing of SSCTs in
the proposed rule for radon. The issue is how to list SSCTs with BAT in
the rule, while at the same time allowing for flexible and timely
updates to the list of SSCTs in the future.
EPA would like to establish a procedure that allows SSCT lists to
be updated by guidance, rather than through the more resource intensive
and time-consuming process of rule-making. For example, under today's
proposal, EPA is including SSCT lists in the rule. This approach fully
satisfies the requirements in Section 1412(b)(4)E(ii) of the Act, which
states that EPA shall include SSCTs in lists of BAT for meeting the
MCL. Since BATs are explicitly listed in rules, it is consistent to
explicitly list SSCTs. Also, Section 1415(a) of the Act requires that
BAT be proposed and promulgated with NPDWRs to satisfy the provisions
for ``general variances'' (variances under Section 1415(a)); therefore,
SSCTs must be listed in the rule if small systems are to be allowed to
use them as BAT in satisfying the provisions for general variances.
Regarding updates to the list of SSCTs, Section 1412(b)(9) of the
Act states that EPA shall review and revise, as appropriate, all
promulgated NPDWRs every six years. However, since revisions of NPDWRs
follow the normal rule-making process of proposing, taking public
comment, and finalizing the rule, the process can be very time-
consuming. While EPA believes that this six year review cycle is
sufficient for updates to lists of BAT, it is unlikely to be sufficient
for updates to lists of SSCTs, since recent improvements in package
plant technologies, POE/POU devices, and remote monitoring/control
technologies have been fairly rapid and future improvements seem
imminent. For this reason, EPA seeks comment on this approach or
alternate approaches that would allow for more timely updates to the
list of SSCTs.
In support of an approach to SSCT list updates that is less formal
and more expeditious than rulemaking, EPA notes that new Section
1412(b)(4)(E)(iv) allows the Administrator, after promulgating an
NPDWR, to ``supplement the list of technologies describing additional
or new or innovative treatment technologies that meet the requirements
of this paragraph for categories of small public water systems.'' This
provision does not contain any reference to or require rulemaking to
update the SSCT list, in contrast with the earlier 1994 House version
(in H.R. 3392) of this provision that specifically required revisions
of the list to be made ``by rule.''
Under one alternative, EPA would publish only an initial list of
SSCTs with the BAT list in 40 CFR 141.66. EPA would also state in the
rule that updates to the list of SSCTs would be done through guidance
published in the Federal Register or through updates to the SSCT
guidance manual. This process would be consistent with the process
already used for listing SSCTs for the currently regulated drinking
water contaminants (USEPA 1998g). A similar alternative approach would
simply ``list'' SSCTs in Section 141.66 by referencing EPA guidance,
which would be published separately and which could be updated
periodically as needed outside of the normal rule-making process.
Finally, EPA could publish both the initial list and the updates solely
in a Federal Register notice or as guidance; however, under this last
approach, only the promulgated BAT listed in the rule (which would not
include SSCTs) would be available for small systems seeking a general
variance under Section 1415(a) of the Act. EPA solicits comments on the
suggested approaches for the listing of SSCTs and on the equivalency of
SSCTs with BAT for the purposes of small systems applying for variances
under Section 1415 of the Act.
(d) Small Systems Affordability Determinations. The affordability
determinations that are used for listing SSCTs are discussed in detail
in recent EPA publications (USEPA 1998i, USEPA 1998e). It should be
noted that aeration is one of the least expensive treatment
technologies for drinking water (USEPA 1993d, NRC 1997) and has been
determined to be affordable for all three small systems size
categories. For the smallest size category (serving 25 to 500 persons),
EPA cost estimates indicate that typical annual household

[[Page 59275]]

costs for aeration (80% removal efficiency, with disinfection and
scaling inhibitor) are $190 per household per year ($/HH/yr). For
systems installing aeration only, household costs for the smallest
system size category are $114 per household per year. Case studies
(n=9, USEPA 1999h) for systems with aeration serving between 25 and 500
persons showed annual household costs ranging from $5 to $97 per
household per year, with an average of $45 per household per year.
Costs reported in these case studies included all pre- and post-
treatments added with aeration. The ``national average per household
cost'' estimated in the Regulatory Impact Analysis is $260 per
household per year for 25-500 persons. This average per household cost
is higher than the estimated per household costs for systems using
aeration since these average costs include not only aeration, but also
the more expensive compliance alternatives (GAC, regionalization, and
``high side'' PTA). Note that the cost for the 25-500 category is a
weighted average of the per household costs for the 25-100 and 101-500
categories reported in Table 7-2 of the Regulatory Impact Analysis.
Also note that monitoring costs of approximately $4.00 per household
per year ($270 per system) are included in the national average per
household costs, but not in the aeration treatment per household costs
reported.
Granular activated carbon (GAC) may be affordable only for very
small flows. EPA's GAC-COST model estimates indicate that GAC may not
be affordable for the smallest size category (25-500 persons served) in
whole. Annual household costs are estimated to be approximately $800 to
> $1000 per household per year. However, case studies of small systems
using GAC to remove radon for very small flows (populations served <
100 persons) show annual household costs ranging from $46 to $77 per
household per year. The large discrepancy between modeled costs and
full-scale case study costs is probably due to the fact that the model
design assumptions are more typical of larger systems, whereas the
designs used in the case studies are much simpler. The American Water
Works Association Research Foundation (AWWARF 1998a) similarly
concludes that EPA's cost estimates for radon removal by GAC are over-
estimates (ibid., p. 190) and that GAC can be cost competitive with
aeration for very small systems (ibid., Chapter 8). Examples of
estimates of POE-GAC capital costs are shown in the next section,
``Treatment Costs''.
2. Treatment Costs: BAT, Small Systems Compliance Technologies, and
Other Treatment
(a) Modeled Treatment Unit Costs. Total production costs associated
with the various technological options for radon reduction, such as
packed tower aeration and diffused bubble aeration installations, have
been examined (USEPA 1999h). For systems that are currently
disinfecting, ninety-nine percent reduction of radon by PTA is
estimated to cost from $2.48/kgal (dollars per 1,000 gallons treated)
for the smallest systems, defined as those serving 100 persons or
fewer, to $ 0.12/kgal for large systems, defined as those serving up to
1,000,000 persons. Eighty percent reduction of radon by PTA without
disinfection is estimated to range from $2.10/kgal to $0.08/kgal for
the same system sizes. For those systems adding disinfection because of
the addition of aeration treatment, disinfection treatment costs for
very small systems are estimated at an additional $1.40/kgal and costs
for large systems are estimated at an additional $0.07/kgal. Aeration
production costs have been adjusted to include costs that account for
the addition of a chemical stabilizer (orthophosphate) by 25 percent of
small systems (those serving 10,000 persons or fewer) and by 15 percent
of large systems. In other words, the production costs shown are
weighted averages that simulate the installation of aeration without
chemical stabilizers by a fraction of the systems and with chemical
stabilizers by the remaining fraction. Chemical stabilizers are used to
minimize fouling from iron and manganese and/or to reduce corrosivity
to the distribution system. Chemical addition cost estimates include
capital costs for feed systems and operations and maintenance costs for
the processes involved. Table VII.A.3 summarizes total production costs
for system size categorizes for 80 percent radon removal. Further
details on costing assumptions and breakdown of the unit treatment
costs can be found in the RIA (USEPA 1999h).

Table VIII.A.3.--Total Production Cost\1\ of Contaminant Removal by BAT for 80 Percent Radon Removal (Dollars/
1,000 Gallons, Late 1997 Dollars)
----------------------------------------------------------------------------------------------------------------
Population Served
---------------------------------------------------------------------------------
25-100 100-500 500-1,000 1,000-3,300 3,300-10,000 >10,000
----------------------------------------------------------------------------------------------------------------
Aeration\2\................... 2.06 0.71 0.39 0.22 0.15 0.08-0.10
Aeration + disinfection....... 3.44 1.09 0.69 0.40 0.22 0.09-0.12
Granular Activated Carbon 0.34 2.16 2.16 NA NA NA
(GAC).
GAC + disinfection............ 1.71 2.54 2.46 NA NA NA
POE GAC + UV disinfection..... 16.99 14.03 NA NA NA NA
----------------------------------------------------------------------------------------------------------------
Notes:
\1\ Cost ranges are estimated from cost equations found in the radon Technologies and Costs document (EPA
1999h), as used in the radon HRCCA (64 FR 9559).
\2\ Aeration costs are weighted to include chemical inhibitor costs (Fe/Mn and corrosion control) for 25 percent
of small systems and 15 percent of large systems.

(b) Case Studies of Treatment Unit Costs. Case studies for aeration
and GAC are reported in detail in the radon Technologies and Costs
document (USEPA 1999h). Total production costs for aeration case
studies ranged from an average of $0.82/kgal for systems serving 25--
100 persons (n = 4, standard deviation = $0.32/kgal, average population
= 58) to $0.19/kgal for systems serving 100--3,300 persons (n = 11,
standard deviation = $0.22/kgal, average population = 873). Total
production costs for GAC ranged from $1.50/kgal for systems serving
fewer than 100 persons (n = 2, standard deviation = $0.48/kgal, average
population = 55) to $0.40/kgal for a system serving approximately
23,000 persons. Production costs for two POE GAC installations ranged
from $0.21/

[[Page 59276]]

kgal to $0.75/kgal. It should be noted that these POE GAC costs do not
include the additional monitoring costs that would apply in a
compliance situation. Annual monitoring costs are generally negligible
compared to annual treatment costs for centralized treatment (<2.5
percent for very small systems to <1 percent for large systems), and
may be significant in the case of POE treatment (USEPA 1998g). For this
reason, the POE GAC case study production costs may under-estimate true
POE GAC costs. In general, the case studies suggest that EPA's modeled
unit costs may be conservative for small systems. Since it is true that
the radon case studies are not necessarily a random sample of all
systems that will be impacted by the future radon rule, it may be
argued that the typical reported costs may differ significantly from
the typical costs of compliance. However, the costs of aeration from
the radon case studies overlap nicely with the costs reported in the
VOCs case studies, which should represent typical costs of compliance.
Given this fact and the large number of case studies used, EPA has
confidence that the case studies represent a best estimate of costs of
treatment for compliance purposes. It should be noted that these
reported case study costs are total costs and include all pre- and
post-treatments added with the radon treatment process.
(c) Treatment Cost Assumptions and Methodology. The general
assumptions used to develop the treatment costs include costs for:
chemicals and general maintenance, labor, capital amortized over 20
years at a 7 percent interest rate, equipment housing, associated
engineering and construction, land for small systems (design flow < 1
mgd per well), and power and fuel (USEPA 1998h, USEPA 1998g, USEPA
1999h). Costs were updated to December 1997 dollars using a standard
construction cost index (Engineering News-Record Construction Cost
Index). Process capital costs for aeration technologies were calculated
using updated cost equations from the Packed Tower Column Air Stripping
Cost Model (USEPA 1993e). Process capital costs for granular activated
carbon and total capital costs for iron and manganese sequestration/
corrosion control, and disinfection were calculated using standard EPA
models (as described in USEPA 1998e and USEPA 1999a). Construction,
engineering, land, permitting, and labor costs were estimated based
upon recommendations from an expert panel comprised of practicing water
design and costing engineers from professional consulting companies,
utilities, State and Federal agencies, and public utility regulatory
commissions (USEPA 1998i). GAC disposal costs are included in the GAC-
COST O&M model. All cost estimates include capital costs for equipment
housing and land for small systems (design flows < 1.0 MGD). It was
assumed that all treatment installations would include disinfection.
Capital and operating & maintenance costs for iron and manganese (Fe/
Mn) sequestration by the addition of zinc orthophosphate were included
for 25 percent of small systems and 15 percent of large systems. Pre-
and post-treatment assumptions are explained in more detail later.
(d) ``Decision Tree''. Compliance costs were estimated assuming
that non-compliant water systems would choose from a variety of
compliance options, including installing a suitable treatment train,
finding an alternate source of water, purchasing water from a near-by
water utility, and using best management practices, like blending or
ventilated storage. The modeled proportions of systems choosing a
compliance pathway (the ``decision tree'') is based on the assumption
that systems will choose the most cost-effective alternative, given the
fact that site-specific factors (e.g., a well located in a suburban
residential area) may force some systems to choose an option that is
more expensive than the least cost alternative. The modeled proportions
were assumed to vary by system size and water quality. More details on
these assumptions are found in the Health Risk Reduction and Cost
Analysis supporting this proposal (64 FR 9559).
(e) Iron and Manganese Assumptions. Treatment costs assume that 25
percent of small systems and 15 percent of large systems installing
aeration will need to add an additional chemical inhibitor (e.g.,
orthophosphate, polyphosphates, silicates, etc.) to minimize the
formation of iron/manganese (Fe/Mn) precipitates and carbonate scale;
to reduce bio-fouling from the growth of Fe/Mn oxidizing bacteria (See,
e.g., Faust and Aly 1998); and to reduce water corrosivity. Although
zinc orthophosphate was assumed to be universally used, this was done
as a simplifying costing assumption, and should not interpreted as
suggesting that zinc orthophosphate is the appropriate inhibitor choice
for all circumstances. Uncertainty analyses were performed in national
cost estimates to simulate a range of choices of chemical inhibitors by
systems and to simulate a range in the percentages of systems requiring
the addition of an inhibitor. It is reiterated that, for the purposes
of iron/manganese control and corrosion control, other chemical
inhibitors may be more appropriate than zinc orthophosphate on a case
by case basis.
(f) Iron and Manganese Occurrence. Tables VIII.A.4 and VIII.A.5
show the estimated co-occurrence of radon with dissolved iron and
manganese in raw ground water for various radon and Fe/Mn levels. It
can be seen from these tables (based on the U.S. Geological Survey's
National Water Information System database, ``NWIS'') that the majority
of ground water systems will be expected to have Fe/Mn source water
levels below the secondary MCLs (SMCLs) for iron (greater than 85
percent of GW samples have less than the SMCL of 0.3 mg/L) and
manganese (greater than 75 percent of GW systems have less than the
SMCL of 0.05 mg/L). Since Fe/Mn precipitation inhibitors are
appropriate for treating combined Fe/Mn levels up to around 1-2 mg/L
(Faust and Aly 1998, USEPA 1999h), this data indicates that the vast
majority of ground water systems (greater than 95 percent) will be
expected to be in situations where inhibitors are sufficient for
handling iron and manganese problems. The cost estimates conservatively
assume that inhibitors will also be used by systems with source water
below the SMCLs for iron and manganese. Systems with Fe/Mn levels above
1-2 mg/L may require oxidation/filtration or a similar removal
technology. However, it should be noted that Fe/Mn levels this high may
cause very noticeable nuisance problems, including ``red water'',
noticeable turbidity, laundry and sink staining, and interference with
the brewing of tea and coffee. It is likely that many systems with
source water Fe/Mn levels this high will have already addressed this
problem.

[[Page 59277]]

Table VIII.A.4.-- Co-Occurrence of Radon With Dissolved Iron in Raw Ground Water\1\^, \2\ (4188 Samples)
----------------------------------------------------------------------------------------------------------------
Dissolved Fe (mg/L) (percent)
Radon (pCi/L) -----------------------------------------------------------------------------
ND <0.3 0.3-1.5 1.5-2.5 >2.5 Totals
----------------------------------------------------------------------------------------------------------------
ND................................ 0.67 0.36 0.21 0.02 0.31 1.57
<100.............................. 2.17 1.72 0.53 0.12 0.48 5.02
100-300........................... 7.55 10.20 2.67 1.34 1.74 23.50
300-1,000......................... 18.89 22.61 \3\ 3.08 0.57 1.31 46.46
1,000-3,000....................... 6.42 9.05 0.74 0.10 0.62 16.93
>3,000............................ 2.10 3.82 0.31 0.02 0.26 6.51
-----------------------------------------------------------------------------
Totals........................ 37.80 47.76 7.54 2.17 4.72 100.00
----------------------------------------------------------------------------------------------------------------
Notes:
\1\ Based on analyses as described in USEPA 1999c.
\2\ The USGS National Water Information System (NWIS) database was used for this analysis.
\3\ Shaded area denotes region where radon level is above MCL and dissolved iron is above 0.3 mg/L, the
secondary MCL for iron.

Table VIII.A.5.--Co-Occurrence of Radon With Dissolved Manganese in Raw Ground Water ^1, ² (4189 Samples)
----------------------------------------------------------------------------------------------------------------
Dissolved Mn (mg/L) (percent)
Radon (pCi/L) ----------------------------------------------------------------
ND <0.02 0.02-0.05 >.050 Totals
----------------------------------------------------------------------------------------------------------------
ND............................................. 0.69 0.26 0.05 0.57 1.57
<100........................................... 2.67 0.84 0.36 1.15 5.02
100-300........................................ 8.00 5.97 2.20 7.33 23.50
300-1,000...................................... 21.99 11.84 3.17 \3\ 9.48 46.48
1,000-3,000.................................... 6.45 5.90 1.24 3.34 16.93
>3,000......................................... 1.43 3.39 0.53 1.17 6.52
----------------------------------------------------------------
Totals..................................... 41.23 28.20 7.55 23.04 100.00
----------------------------------------------------------------------------------------------------------------
Notes: \1\ and \2\: See Table VIII.A.4.
\3\ Shaded area denotes region where radon level is above MCL and dissolved manganese is above 0.05 mg/L, the
secondary MCL for manganese.

A similar analysis of the National Inorganic and Radionuclides
Survey (NIRS) database, which sampled finished ground water, suggests
that greater than 81 percent of GW systems sampled have dissolved Fe/Mn
levels less than 0.3 mg/L and greater than 97 percent of systems
sampled have levels less than 1.5 mg/L (USEPA 1999h). Table VIII.A.6
compares combined Fe/Mn levels predicted by the NIRS database to occur
in finished ground water with levels predicted by NWIS to occur in raw
ground water. This table is consistent with expectations that the vast
majority of ground water systems will have combined Fe/Mn levels below
1-2 mg/L and that a significant fraction of ground water systems with
Fe/Mn levels above the SMCL are already taking measures to reduce Fe/Mn
levels.

Table VIII.A.6.--Co-Occurrence of Radon With Dissolved Combined Iron and Manganese in Raw and Finished Ground
Water
----------------------------------------------------------------------------------------------------------------
Percent of samples with dissolved
combined Fe and Mn (mg/L) (percent)
Ground water type --------------------------------------- Data sources
<0.3 <1.5
----------------------------------------------------------------------------------------------------------------
Finished Ground Water............ >81, >93 >97 >99 NIRS,\1\ AWWA Water:/Stats \2\
Raw Ground Water................. >85, >71 >95 >88 NWIS,\3\ AWWA Water:/Stats
----------------------------------------------------------------------------------------------------------------
Notes:
\1\ ``National Inorganics and Radionuclides Survey'': See USEPA 1999c for references.
\2\ American Water Works Association, ``Water:/Stats, 1996 Survey: Water Quality''.
\3\ USGS, National Water Information System.

An analysis of the American Water Works Association (AWWA)
``Water:/ Stats'' database corroborates these conclusions: average Fe/
Mn levels in finished water from 442 ground water systems showed that
greater than 93 percent of the systems had combined Fe/Mn levels less
than 0.3 mg/L and greater than 99 percent of systems had combined Fe/Mn
levels less than 1.5 mg/L (AWWA 1997); average Fe/Mn levels in raw
ground water from 433 systems showed that greater than 71 percent of
systems had combined Fe/Mn levels less than 0.3 mg/L and greater than
88 percent of systems had Fe/Mn levels less than 1.5 mg/L. While this
analysis does support the conclusions from NIRS and NWIS, it should be
noted that the AWWA ``Water:/Stats Survey'' is skewed towards large
ground water systems: only 3.4 percent of the systems surveyed serve
fewer than 10,000 persons, whereas at the national

[[Page 59278]]

level, greater than 95 percent of ground water systems serve fewer than
10,000 persons. In comparison, NIRS was designed to be nationally
representative of contaminant occurrence in CWSs, while NWIS is a
``data bank'' in which the U.S. Geological Survey stores water
contaminant data from its various studies. While the data in NWIS was
not collected as part of a designed national survey (and hence can not
be claimed to be necessarily nationally representative), it is arguably
nationally representative based on its large sample size and its wide
distribution of sample collection locations (USEPA 1999c).
(g) Disinfection Assumptions. It was assumed that all systems
adding treatment would include disinfection. Since a significant
fraction of ground water systems already disinfect, the percentage of
systems that would have to add disinfection was estimated from a
``disinfection-in-place baseline'', as described in the Radon Health
Risk Reduction and Cost Analysis published on February 26, 1999 (64 FR
9559). It should be noted that this baseline is nationally
representative. Some States will, of course, have higher proportions of
ground water systems with disinfection-in-place (e.g., those States
that require that ground water systems disinfect) and some will have
lower proportions. Since the cost estimates being calculated are at the
national level, EPA believes that this assumption is valid since this
will over-estimate costs for systems in some States and under-estimate
costs for systems in other States, with the respective cost errors
tending to cancel at the national level. As a simplifying cost
assumption, chlorination was assumed for all systems adding
disinfection. The actual choice of disinfection technology should, of
course, be made on a case by case basis. The fact that many systems
will choose disinfection systems other than chlorination and that some
systems will not add disinfection at all is captured in the uncertainty
analysis, described later in this section.
(h) Comparison of Modeled Costs with Real Costs from Case Studies.
Figure VIII.A.1 compares modeled total capital costs against case
studies of actual aeration treatment installations for radon and VOCs
found in the literature and gathered by EPA. It should be noted that
these case studies include all pre- and post-treatments capital costs
and costs for land, housing structures, permits, and all other capital
added with the aeration process. If EPA's assumptions regarding pre-
and post-treatments were seriously flawed, this comparison would
demonstrate the fact. As can be seen, EPA's models fit the data fairly
well and, in fact, Figure VIII.A.2 shows that the ``typical cost
model'' rather closely approximates a power fit through the capital
cost data for the larger systems and significantly over-estimates
capital costs for small systems.
The ``PTA Cost Model'' represents EPA's best estimate of the costs
of constructing and operating a PTA system under the associated design
assumptions (steel shell, below-ground concrete clearwell, structure,
etc.). This design was intended to be fairly typical of those systems
serving more than 500 persons and up to 1,000,000 persons. The ``High
Side PTA Cost Model'' represents EPA's best estimate of the costs of
constructing and operating a PTA system under the same basic treatment
design, but including significantly higher land, structure, and
permitting costs. This model was intended to be fairly typical of
systems that are ``land-locked'' in suburban or urban areas where land
costs, building codes, and permitting demands may be much higher than
for typical situations. The ``Low Side PTA Cost Model'' represents
EPA's best estimate of the costs of constructing and operating a PTA
system using designs more typical of very small systems, including
package plant installations. This model is described in the Radon
Technologies and Costs Document (USEPA 1999h). As can be seen in Figure
VIII.A.1, the PTA Cost and High Side PTA Cost models are representative
of the systems with design flows greater than 0.1 MGD. All of these
models tend to over-estimate costs for those systems with smaller
design flows.
The relative percentages of non-compliant systems modeled by the
low-, typical-, and high-side costs are shown in the ``decision tree''
in Table 7-3 of the Regulatory Impact Assessment supporting this
proposal. As part of the uncertainty analysis (described later in this
section), these decision tree percentages were varied significantly.
The results and assumptions are presented in detail in Section 10.8.3
of the Regulatory Impact Assessment. Based on a sensitivity analysis of
the relative impacts of all the cost elements studied, the variance in
the decision tree percentage values had much less of an impact on
national costs compared to the variance in the treatment unit costs ($/
kgal).

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Figure VIII.A.2 compares the EPA aeration capital cost models
against best fits to aeration capital cost case studies from the Radon
Technologies and Costs Document (which includes aeration installations
for VOCs) and to capital costs for radon case studies as reported by
American Water Works Association Research Foundation (AWWARF 1998b). In
general, EPA's unit cost estimates are supported by the case studies
cited previously and by the findings reported by the AWWARF (AWWARF
1998b).
Figure VIII.A.3 shows that EPA's modeled operations and maintenance
(O&M) costs are representative of the case study cost data. It should
be noted that EPA is modeling incremental O&M aeration costs
(additional O&M costs due to the addition of radon treatment) and that
many of the radon case studies and all of the VOCs case studies report
total O&M costs, which include O&M costs not related to the removal of
radon. For this reason, the case study O&M costs would be expected to
be considerably higher than the modeled costs, especially for the
larger systems (which tend to have other processes in place that
require substantial O&M costs). For example, most of the case studies
using disinfection already had disinfection in place before adding
aeration for radon. Since it is very difficult to separate the
individual components of O&M costs without detailed site-specific
information, these disinfection O&M costs are included in the O&M costs
shown even though they are not related to treatment added for radon. As
described previously, EPA did model O&M costs for disinfection and
sequestration for iron and manganese and did include these in its
national cost estimates. Figure VIII.A.3 compares modeled O&M costs for
aeration with and without disinfection. Modeled O&M costs for iron/
manganese stabilization and corrosion control are included through a
weighting procedure that simulates 25 percent of small systems and 15
percent of large systems adding a chemical inhibitor. EPA solicits
public comment and data on treatment costs and performance for the
removal of radon from drinking water.

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Figures VIII.A.4 and VIII.A.5 compare the modeled capital costs and
O&M costs for GAC against actual costs reported in case studies (USEPA
1999a, AWWARF 1998b). As can be readily seen, EPA's modeled costs are
significantly higher than the actual costs, especially so for very
small flows. To account for this discrepancy, EPA used the best fit
through the case study data to generate a calibrated GAC model for
capital and O&M costs. EPA calculated GAC treatment costs based on this
model and did an uncertainty analysis on GAC costs assuming that while
the modeled costs were typical, they could be as high as the GAC-COST
predictions. This procedure is described in more detail in the radon
HRRCA.
EPA also estimated point-of-entry GAC (POE-GAC) costs for very
small systems. While capital and standard maintenance costs may be
affordable ($100-$350 per household per year), monitoring costs can
make POE-GAC much more expensive. EPA estimates (USEPA 1998g) that
monitoring costs alone can be as much as $140 per household per year. A
``high end'' estimate for POE-GAC is $1,000 per household per year. If
more cost-effective monitoring and maintenance program schemes are
devised, these costs may be considerably lower.
In general, treatment costs may vary significantly depending on
local circumstances. For example, costs of treatment will be less than
shown if contaminant concentration levels encountered in the raw water
are lower than those used for the calculations or if an existing
clearwell can be retrofitted for aeration. However, costs of treatment
will be higher if oxidation/filtration pre-treatment is required for
iron and manganese removal or if water must be piped from the well-head
to an off-site area for treatment.

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(i) Uncertainty Analysis for Treatment Costs. To estimate the
uncertainty in national treatment costs, EPA estimated credible ranges
and distributions of values for the most important factors (inputs)
affecting costs. Distributions of selected inputs were then used in a
Monte Carlo analysis to explore the uncertainty in national costs. The
cost factors that were analyzed include:
Numbers of systems in the various size categories;
The distribution of the numbers of sources (wells) per
system in each size category;
Distributions of populations served in each size category;
Annual household water consumption;
Proportions of systems and wells exceeding radon limits;
and
Unit costs of radon treatment technologies (aeration and
GAC).
Each of these inputs was modeled using probability distributions
that reflect the spread in the available data. In some cases,
(distributions of populations served, daily household water
consumption, unit costs) variability was estimable from SDWIS, the
CWSS, or other sources. In the case of the numbers of systems of
different sizes, the estimated variability was greatest for the
smallest systems, less for the moderate size systems, and the numbers
of the largest systems (serving greater than 100,000 customers) was
assumed to be known with certainty. The variation in the proportions of
systems and sources above radon limits was estimated based on EPA's
recent analysis (USEPA 1999l) of inter- and intra-system radon
variability in radon levels.
In addition to these inputs, the estimated percentages of systems
choosing particular treatment technologies (the ``decision tree'') were
allowed to vary as well. Three decision tree matrices were used,
corresponding to a central tendency estimate of the proportions of
systems choosing specific mitigation technologies, and to lower- and
higher-cost distributions of technology selection. When the simulation
was run, the central tendency matrix was selected in 80 percent of the
iterations, and the low- and high-cost decision matrices were selected
in ten percent of the iterations each.
The variability in the estimated mitigation costs was examined
using a conservative test case in which all systems above an MCL of 300
pCi/L were assumed to mitigate to comply with the MCL. The results of
the analysis are described in detail in the radon Health Risk Reduction
and Cost Analysis. In general, the distribution of cost estimates, even
with all the variables included in the Monte Carlo analysis, is much
narrower than the corresponding distribution of risk and benefit
results. For this hypothetical scenario, the fifth percentile cost
estimate is $455 million per year, while the 95th percentile estimate
is $599 million per year (only 32 percent higher). The compactness in
spread in national costs relative to the spread in national benefits is
primarily due to the fact that the variability in the individual cost
model inputs is low relative to the variability in some of the inputs
(e.g., individual risk) to the benefits model.
(j) Potential Interactions Between the Radon Rule and Upcoming and
Existing Rules Affecting Ground Water Systems: Aeration and GAC are BAT
for more than 25 and 50 currently regulated contaminants, respectively.
Both technologies have been well-demonstrated and the secondary effects
of each technology are well understood (See, e.g., Cornwell 1990,
Umphres and Van Wagner 1986, AWWA 1990). These technologies are also
used to remove other contaminants from drinking water, including taste
and odor causing compounds. The Community Water System Survey (USEPA
1997a) indicates that 2 to 5 percent of ground water systems serving
fewer than 500 persons currently have aeration treatment in place. Of
systems serving more than 500 persons, 10-25 percent of these systems
have aeration treatment at one or more entry points.
In the case of aeration, these secondary effects include carbon
dioxide release (pH increase), oxygen uptake, and potential bacterial
density increases, all of which potentially impact other existing and
future drinking water regulations that pertain to ground water. In the
case of GAC treatment, potential bacterial density increases are of
concern. These potential interactions are described in a following
section. (Concerns that are specific to radon removal and secondary
effects due to other contaminants, e.g., radium and uranium, are
discussed in part 3 of this Section.)
(k) Ground Water Rule: Since the treatment techniques applicable to
the removal of radon, i.e., aeration, GAC, and/or ventilated storage,
may result in increases in microbial activity (NAS 1999b, Spencer et
al. 1999), it is important that water systems determine whether post-
treatment disinfection is necessary. The ``Ten States Standards''
(GLUMRB 1997) suggest that disinfection should follow ground water
exposure to the atmosphere (e.g., aeration or atmospheric storage). The
Ten State Standards also suggest that systems using GAC treatment
implement ``provisions for a free chlorine residual and adequate
contact time in the water following the [GAC] filters and prior to
distribution.'' While EPA is not requiring that disinfection be used in
conjunction with any treatment for radon, it is including costs for
disinfection with treatment in accordance with good engineering
practice. Cost assumptions for disinfection, including clearwell sizing
for 5-10 minutes of contact time, are consistent with 4-log viral
inactivation for ground water, which is expected to be consistent with
requirements in the upcoming Ground Water Rule.
It should be noted that air is not a significant pathogen vector
and thus aeration does not necessarily increase pathogenic risk for
ground water users. However, bacterial activity can increase upon
aeration and/or treatment with GAC. In the case of aeration treatment,
bacteria that oxidize iron and/or sulfide may proliferate because of
the oxygen increase; in the case of GAC treatment, bacteria may
proliferate since the GAC surface tends to accumulate organic matter
and nutrients that support the bacteria. In either case, heterotrophic
plate count limits may become high enough to be of concern and for this
reason disinfection may be necessary (USEPA 1999h, NAS 1999b).
(l) Disinfectants and Disinfection Byproducts (D/DBP) Rule:
Commonly used disinfection practices for ground water systems include
chlorination and, especially for small systems with limited
distribution systems, ultraviolet (UV) radiation. Disinfection is used
by many ground water systems because it decreases microbial risks from
microbial contamination of ground water (NAS 1999b). However, there is
a trade-off between a reduction in microbial risks and the risks
introduced from disinfection by-products. Various disinfectant by-
products (DBPs) can be formed depending on the disinfectant used, the
disinfectant concentration and contact time, water temperature, the
levels of DBP pre-cursors like natural organic materials and bromide,
etc. For example, chlorination by-products like trihalomethanes can
result from the interaction between chlorine chemical species and
naturally occurring organic materials (NOM) and bromate can result from
the ozonation of waters with sufficiently high levels of naturally
occurring bromide ion.
Ground water systems tend to have significantly lower
trihalomethane (THM) organic precursors than surface waters, although
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used as a surrogate for formation of one important class of DBPs, total
trihalomethanes (THM), since the THM formation potential of chlorinated
waters correlates with TOC. As reported in the proposed Disinfectants
and Disinfection Byproducts Rule (July 29, 1994: 59 FR 38668), a survey
of surface waters showed TOC levels at the 25th, 50th, and 75th
percentiles of 2.6, 4.0, and 6.0 mg/L, respectively; ground waters
showed TOC levels at the same percentiles of ``non-detect'', 0.8, and
1.9 mg/L, respectively. Nationally, typical ground waters have low TOC
levels. However, some areas of the U.S., e.g., the Southeastern U.S.
(EPA Region 4), have some aquifers with high TOC levels.
One approach for the minimization of DBP formation in drinking
water is to employ a disinfectant other than chlorine. Primary
disinfection with chloramination, ozonation, or UV radiation are
examples. However, other considerations may apply. For example,
ozonation of ground water with sufficiently high bromide levels may
result in significant levels of the DBP bromate. If a residual is
required, it may be necessary to add secondary chlorination to maintain
a residual in the distribution system. Other strategies include
reducing the precursor concentration prior to chlorination, removal of
THMs after their formation, and the installation of a second
chlorination point in the distribution system. This last approach
allows much lower chlorination levels to be used for primary
chlorination, which greatly reduces THM formation.
While these strategies may be employed to minimize the formation of
DBPs and, thereby reducing potential DBP risks and avoiding MCL
violations for the DBP rule, there are other reasons to expect minimal
interactions between the radon rule and the D/DBP rule. Namely, EPA
expects that the radon rule will not result in a large percentage of
systems adding disinfection because of the need to treat for radon.
Since the primary regulatory option for small ground water systems is
the MCL/MMM option (MCL = 4000 pCi/L) and less than one percent (1%) of
small systems have radon levels that high, EPA does not expect many
small systems to add treatment for radon in response to the radon rule,
resulting in a very small percentage of small systems adding
disinfection. Roughly half of all small systems already half
disinfection in place already, further suggesting minimal small system
impact from the radon rule. While EPA also expects that many large
systems will also adopt the MCL/MMM option, EPA estimates that 95-97
percent of large ground water systems are already disinfecting, and
thus would not have to add disinfection if treating for radon. For the
expected small minority of systems that do add chlorination
disinfection with radon treatment, the trade-off between a reduction in
risks from radon exposure to an increase in risk from disinfection by-
products will need to be carefully considered by the system installing
treatment and strategies to minimize DBP formation should be
implemented (NRC 1997, NAS 1999b, Spencer et al. 1999).
(m) Lead and Copper Rule: For several reasons, it is expected that
few systems already in compliance with the Lead and Copper Rule will
experience direct cost impacts because of the Radon Rule. Systems
serving fewer than 50,000 persons do not have to modify corrosion
control practices if the lead and/or copper contaminant trigger levels
are not exceeded. For the reasons explained next, aeration is not
expected to result in increased lead and copper levels in the vast
majority of cases. While larger systems will have to include radon
treatment into their over-all ``optimal corrosion control'' plans as
they are updated, aeration tends to reduce or maintain corrosivity
levels and should not result in measures beyond those included in the
national costs for the proposed radon rule.
Aeration of ground water for radon treatment tends to raise the pH
of water (Kinner et al. 1990, as cited by NAS 1999b, Spencer et al.
1999), since it tends to remove dissolved carbon dioxide, which forms
carbonic acid when dissolved in water. In a study of VOCs removal by
aeration, the American Water Works Association (AWWA 1990) reported
that the net effect of aeration was ``no increase in corrosivity'': The
reduction in carbon dioxide levels resulted in higher pH and in
increased stability of carbonate minerals that serve to protect
distribution systems, negating the corrosive effects of increased
oxygen levels. The NAS concludes (NAS 1999b and references cited within
Spencer et al. 1999) that studies suggest that corrosivity tends to
decrease with aeration, but that a minority of systems that aerate may
have to add a corrosion inhibitor to stabilize the impacts of the
increased oxygen levels. As described previously, EPA has assumed in
its national costs that, of the systems that install aeration, 25
percent of small systems and 15 percent of large systems will add
chemical inhibitors for the dual purposes of corrosion control and the
control of iron and manganese.
(n) Arsenic Rule: It is expected that there will be no significant
negative relationships between compliance measures for the Arsenic and
Radon Rules. In fact, one of the few expected impacts is beneficial:
aeration plus disinfection may serve to pre-oxidize As(III) to the more
readily removable As(V) form. However, the benefits estimated in this
notice do not reflect this potential benefit.
3. Descriptions of Technologies and Issues
(a) Aeration. Aeration techniques for removal of radon from
drinking water include active processes such as diffused bubble
aeration (DBA), packed tower aeration (PTA), simple spray aeration,
slat tray aeration, and free fall aeration, with or without spray
aerators. Passive aeration processes such as free-standing, open air
storage of water for reduction of radon may be effective for systems
requiring lower removal efficiencies. Additional removal of radon via
radioactive decay (into the daughter products of radon) may also occur
in storage tanks and in pipelines which distribute drinking water,
reducing radon by approximately 10 to 30 percent, within 8 to 30 hour
detention periods. Although all of these aeration processes may be
effective, depending on site specific conditions, only active aeration
processes are considered BAT. Site specific considerations that may
influence an individual water system's choice of treatment include
source water quality (including concentrations of radon and other
contaminants removed or otherwise affected by aeration), institutional
or labor constraints, wellhead location, seasonal climate (e.g.,
temperature), site-specific design factors, and local preferences.
Identical treatment designs may achieve different radon removal
efficiencies at individual water systems, depending upon these factors.
A design for a technology may be altered to increase the radon removal
efficiency, e.g., an increase in the technology's air:water ratio (the
respective flows of air and water being mixed) may increase the radon
removal efficiency to account for local conditions that depress the
radon removal efficiency. In some cases, the removal efficiency
requirement may be high enough that only high performance aeration
technologies (e.g., packed tower aeration) will achieve the desired
removals.
High performance aeration technologies, e.g., packed tower aeration
(PTA) and package plant aerators with high air:water ratios like
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aeration (MSBA), provide the most efficient transfer of radon from
water to air, with the ability to remove greater than 99 percent of
radon from water. A supply which requires a smaller reduction of radon,
e.g., 50 percent, could opt to install one of these technologies and
treat 50 percent of its source water and subsequently blend the treated
with raw water, or it may design a shorter packed tower to achieve
compliance with the MCL, both of which are significantly cheaper than
treating the entire flow to 99 percent radon removal. Other advantages
of high performance aeration include: removal of hydrogen sulfide,
carbon dioxide, and VOCs, and oxidation of iron and manganese. Full-
scale PTA, STA, and MSBA installations have been constructed for the
removal of radon for very small up to medium sized-systems (AWWARF
1998b, USEPA 1999a). In addition to these case studies, full-scale
aeration facilities for VOCs removal for medium to large-sized systems
have been reported in the literature (AWWA 1990). Since radon is more
easily air stripped than most volatile organic compounds, and high
performance aeration technologies have been shown to be efficient forms
of aeration for VOC removal (Kavanaugh and Trussell 1989, Dyksen et al.
1995), these technologies are appropriate as BAT for radon.
Treatment issues regarding aeration have been discussed in the
literature (e.g., Dihm and Carr 1988, Kinner et al. 1990b, Dell'Orco et
al. 1998, AWWARF 1998b) and by EPA (USEPA 1999d). These issues include
the potential for bacteria fouling (e.g., iron/manganese/sulfide
oxidizing bacteria), iron and manganese chemical precipitation and
scaling, and corrosivity changes. Bacteria fouling and Fe/Mn scaling
may clog or otherwise impede operations at an aeration facility,
requiring preventative maintenance and/or periodic cleaning. Regarding
corrosivity, the aeration process tends to reduce carbon dioxide levels
(and raise pH, which tends to decrease corrosivity) and introduce
oxygen (which tends to increase corrosivity). Whether or not
corrosivity increases or decreases depends on site specific factors. In
general, the degree to which these treatment issues may occur depends
on the source water quality, ambient water and air temperatures, pre-
and post-treatments added or in place, the type of aeration used, and
other factors. To account for the cost impacts of dealing with Fe/Mn/
carbonate scaling, EPA has included the capital and operation and
maintenance costs of pre-treatment with a scalant stabilizer (which
also may serve as a corrosion inhibitor, depending upon the type of
corrosivity). Pre-/Post-treatment with a disinfectant to control
biological fouling and to provide four-log viral deactivation (assuming
a five minute contact time at 1.0-1.5 mg/L chlorine) has also been
assumed in cost estimates. EPA assumed that those groundwater systems
without disinfection already in place will add disinfection when
aerating.
The PTA process involves the use of packing materials to create
pore spaces that greatly increase the air:water contact time for a
given flow of air into water. In counter-current PTA, the water is
pumped to the top of the tower, then distributed through the tower with
spray nozzles or distribution trays. The water flows downward against a
current of air, which is blown from the bottom of the tower by forced
or induced draft. The air space at the top of the tower is continually
refreshed with ventilators. This design results in continuous and
thorough contact of the water with ambient air. The factors that
determine the radon removal efficiency are the air:water ratio (the
ratio of air blown into the bottom of the tower and the water pumped
into the top of the tower), the type and number of packing material,
the internal tower dimensions, the water loading rate, the radon level
in the influent and in the ambient air, and the water and air
temperatures. A typical packed tower aeration installation consists of:
(1) the tower: a metal (stainless steel or aluminum), fiber-glass
reinforced plastic, or concrete tower with internals consisting of
packing material with supports and distributors, (2) a blower or
blowers, (3) effluent storage, which is generally provided as a
concrete clearwell (airwell) below the tower; very small systems may
use metal or plastic storage tanks, and (4) effluent pumping. Pumping
into the tower is performed either through modification or replacement
of the original well pump.
Commercially available high performance package plant aerators
(USEPA 1999a, AWWARF 1998b) include multi-stage bubble aerators (MSBA),
shallow tray aerators (STA), and other high air:water ratio designs.
MSBA units typically consist of shallow (typically less than 1.5 feet
deep) high-density polyethylene tanks partitioned into multiple stages
with stainless steel or plastic dividers. Each stage is provided with
an aerator, each of which is connected to the air supply manifold. STA
units typically consist of one to six stacked tray modules (each 18 to
30 inches deep). Water is pumped through each tray as air is blown
through diffusers at the bottom of the tray, creating turbulent mixing
of the air and water. These package plant aerators have several
distinct advantages: they are low-profile and compact (small
footprint), are considered straightforward to install, and are
relatively easy to maintain.
Other varieties of active aeration include diffused bubble
aeration, which involves the bubbling of air into the water basin (of
varying depth and design) via a set of air bubble diffusors. Forms vary
from designs with shallow depth tanks containing thousands of diffusers
to ``low technology'' designs involving bubbling air into a storage
tank via a perforated hose connected to a blower. Some forms of
diffused bubble aeration can remove up to 99.9 percent of radon from
drinking water; simpler varieties can remove from 80 to > 90 percent of
radon. One of the main advantages of diffused bubble aeration is its
potential for making use of existing basins for the aeration process,
which substantially reduces construction costs. Even if the aeration
basin must be newly constructed, this process can be more cost
effective than PTA for small systems. The disadvantages of diffused
aeration include the requirement for increased contact time, the
impracticality of large air-to-water ratios because of air pressure
drops, and overall less efficient mass transfer of radon from water.
The level of contact between air and water achievable in a packed tower
aerator is difficult to obtain in a simple diffused air system (i.e.,
forms like MSBA can achieve comparable contacts).
The Radon Technology and Cost document (USEPA 1999h) summarizes
treatability studies for four diffused bubble aeration installations.
One of the case studies involves a full-scale diffused aeration plant
in Belstone, England, which provided a long-term radon removal
efficiency of 97 percent. This plant (design flow of 2.5 mgd) was
designed with an air:water ratio, using 2,800 air diffusers, each
designed to supply a maximum of 0.8 cubic feet per minute, and a 24-
minute retention time. In a field test of a diffused bubble aeration
system, Kinner et al. (1990) report that removals of 90 to 99 percent
were achieved at air-to-water ratios of 5 and 15, respectively.
Spray aerators direct water upward, vertically, or at an angle,
dispersing the water into small droplets, which provide a large
air:water interfacial area for radon volatilization. In single pass
mode, depending upon the air:water ratio, removal efficiencies of >50
to >85 percent can be achieved. In multiple pass mode, 99 percent
removals can be

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achieved. Most of the advantages cited previously for diffused aeration
also apply to spray aeration. Disadvantages include the need for a
large operating area and operating problems during cold weather months
when the temperature is below the freezing point. Costs associated with
this option (for all sizes of water treatment plants) have not been
developed by EPA, but case studies (USEPA 1999a, AWWARF 1998b) indicate
that it is cost-competitive with other small systems aeration
technologies.
EPA has evaluated other, less technology-intensive (``low-
technology''), options which may be suitable for small water systems,
and which may cost less than the options described previously to
install and operate (Kinner et al. 1990b, USEPA 1999a, AWWARF 1998b).
These options include: atmospheric storage, free fall with nozzle-type
aerator, bubble aerators, blending, and slat tray aerators. Limited
data concerning these low-technology alternatives are reviewed in USEPA
1999a and AWWARF 1998b. Case studies show that atmospheric storage with
a detention time of nine hours resulted in removals of 7-13 percent and
a detention time of 30 hours in removals of around 35 percent. Dixon
and Lee (1987) report that blending 6.34 MG of well water with a radon
level of 1079 pCi/L with 18.34 MG of surface water resulted in effluent
water with 226 pCi/L. Other storage case studies (detention times
ranging from 8 to 23 hours) show that free-fall into a tank, free-fall
with simple bubble aeration, simple spray aeration with free-fall, and
simple bubble aeration remove 50-70 percent, 85-95 percent, 60-70
percent, and 80-95 percent of radon, respectively. More detail on an
example will illustrate the simplicity of the treatment involved: the
case study for ``free-fall with simple bubble aeration'' cited
previously involved the introduction of water through two feet of free
fall into a tank equipped with garden hose (punctured) bubble aerators,
where the air was supplied by a laboratory air pump. Kinner et al.
(1990b) concluded that very effective radon reduction can be achieved
by simple aeration technologies that may be easily applied in small
communities.
(i) Evaluation of Radon Off-Gas Emissions Risks. Since this notice
contains a proposal to reduce radon concentrations in drinking water by
setting an MCL, and the EPA is proposing aeration as BAT for meeting
the MCL, the Agency undertook an evaluation of risks associated with
potential air emissions of radon from water treatment facilities due to
aeration of drinking water. In the first evaluation (USEPA 1988a,
1993a), EPA used radon data from 20 drinking water systems in the U.S.
which, according to the Nationwide Radon Survey (1985), contained the
highest levels of radon in drinking water and affected the largest
populations and/or drinking water communities. EPA estimated the
potential annual emissions (in pCi radon/yr) from these facilities,
assuming 100 percent radon removal.
These radon emissions estimates were used as inputs to the AIRDOS-
EPA model, which is a dispersion model that can be used to estimate the
concentration of radon at a point some distance from the point source
(e.g., a packed tower vent). This model is the predecessor to the newer
CAP-88-PC model, which combined AIRDOS with the DARTAB model, which
estimates the total lifetime risk to individuals and the total health
impact for populations. The underlying physical models in CAP-88 are
essentially the same as those underlying AIRDOS and DARTAB (USEPA
1992c). In fact, the main differences between CAP-88-PC model and its
predecessors is that CAP-88-PC is intended for wide-spread use in a
personal computer environment (the CAP-88-PC model and its supporting
documentation can be downloaded from the EPA homepage, http://
www.epa.gov/rpdweb00/assessment/cap88.html). EPA has made comparisons
between the AIRDOS-EPA dispersion model results and actual annual-
average ground-level concentrations and found very good agreement. EPA
has studied the validity of AIRDOS-EPA and concluded that its
predictions are within a factor of two within actual average ground-
level concentrations, the results of which are as good as any existing
comparable model (USEPA 1992c).
Estimates of ground-level radon exposure were made for the
following parameters: air dispersion of radioactive emissions,
including radon and progeny isotopes of radon decay; concentrations in
the air and on the ground; amounts of radionuclides taken into the body
via inhalation of air and ingestion of meat, milk, and fresh
vegetables, dose rates to organs and estimates of fatal cancers to
exposed persons within a 50 kilometer radius of the water treatment
facilities. Estimates of individual risk and numbers of annual cancer
cases were completed for each of the 20 water systems, as well as a
crude estimate of U.S. risks (total national risks) based on a
projection of results obtained for the 20 water systems. These
estimates were based on exposure analyses on a limited number of model
plants, located in urban, suburban and rural settings, which were
scaled to evaluate a number of facilities. (A similar approach has been
used by the Agency in assessing risks associated with dispersion of
coal and oil combustion products.) The risk assessment results for the
20 systems indicate the following: a highest maximum lifetime risk of 2
^x 10^-\5\ for individuals within 50 km of one of
these systems, with a maximum incidence at the same location of 0.003
cancer cases per year; an estimate of annual cancer cases for all 20
systems of 0.0038 per year; and a crude U.S. estimate of 0.09 fatal
cancer cases/year due to air emissions if all drinking water supplies
are treated by aeration to meet an MCL of 300 pCi/L. Two other cases
were evaluated: (1) Assuming that small drinking water systems are
treated by aeration to meet the MCL/MMM option of 4000 pCi/L and large
systems are treated to meet the MCL of 300 pCi/L, the best estimate of
total national fatal cancer cases per year due to radon off-gas
emissions is 0.04 cases/year, and (2) Assuming that all systems treat
by aeration to meet the (A)MCL/MMM option of 4000 pCi/L , the best
estimate is 0.01 cases/year. These results of the risk assessment for
potential radon emissions from drinking water facilities are summarized
in Table VIII.A.7. For all MCL options shown, the maximum lifetime
individual risks from radon off-gas are much smaller (100 to 70,000
times smaller) than the average lifetime individual risks from the
untreated water. Regarding national population risks (fatal cancer
cases per year), the estimated population risk from radon off-gas is
850 to 17,000 times smaller than the estimated population risk from the
untreated water.

[[Page 59290]]

Table VIII.A.7.--Estimates of Risks at 20 Sites Due to Potential Radon Emissions From Aeration Units and Crude
Projection of Total U.S. Risk \1\
----------------------------------------------------------------------------------------------------------------
Concentration Emissions from Population risk \2\
Modeling scenario in water (pCi/ facility (Ci Maximum lifetime (fatal cancer cases
L) Rn/Yr) individual risk \2\ per year)
----------------------------------------------------------------------------------------------------------------
20 Facilities Modeled:
1............................. 1,839 2.79 3 x 10^-7 7 x 10^-5
2............................. 5,003 6.22 6 x 10^-7 2 x 10^-4
3............................. 2,175 2.85 3 x 10^-7 9 x 10^-5
4............................. 1,890 20.89 6 x 10^-6 1 x 10^-4
5............................. 1,310 1.81 5 x 10^-7 9 x 10^-7
6............................. 1,329 91.80 9 x 10^-6 1 x 10^-3
7............................. 4,085 2.26 2 x 10^-7 3 x 10^-5
8............................. 10,640 1.18 1 x 10^-7 1 x 10^-5
9............................. 3,083 0.55 5 x 10^-8 7 x 10^-6
10............................ 3,270 9.04 2 x 10^-5 1 x 10^-3
11............................ 2,565 3.54 7 x 10^-6 6 x 10^-4
12............................ 4,092 13.75 2 x 10^-7 3 x 10^-5
13............................ 16,135 2.23 2 x 10^-7 3 x 10^-5
14............................ 3,882 0.27 8 x 10^-8 5 x 10^-6
15............................ 1,244 1.03 3 x 10^-7 2 x 10^-5
16............................ 2,437 1.35 4 x 10^-7 5 x 10^-7
17............................ 996 8.94 9 x 10^-7 2 x 10^-4
18............................ 7,890 0.87 3 x 10^-7 6 x 10^-6
19............................ 9,195 1.02 3 x 10^-7 1 x 10^-5
20............................ 7,500 1.04 3 x 10^-7 6 x 10^-6
-----------------------------------------------------------------------------
Totals for All 20 Facilities...... 161 ..................... 0.004
----------------------------------------------------------------------------------------------------------------
Totals Assuming All U.S. Community 3700 ..................... 0.09
Water Systems Treat to 300 pCi/L
\3\, i.e., All Systems Meet MCL
of 300 pCi/L.
----------------------------------------------------------------------------------------------------------------
Totals Assuming All Small U.S. 1600 ..................... 0.04
Drinking Water Facilities Treat
to 4000 pCi/L \3\ and All Large
U.S. Drinking Water Treat to 300
pCi/L, i.e., All Small Systems
Meet MCL of 4000 pCi/L and All
Large Systems: meet MCL of 300
pCi/L.
----------------------------------------------------------------------------------------------------------------
Totals Assuming All U.S. Drinking 240 ..................... 0.01
Water Facilities Treat to 4000
pCi/L \3\, i.e., All Systems meet
MCL of 4000 pCi/L.
----------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------
Notes:
\1\ Estimates of Risk Assessment Using AIRDOS-EPA to estimate radon exposure. The total U.S. risk is based on
the very conservative projection that all CWSs will treat to 200 pCi/L, USEPA 1993b.
\2\ Risks are based on the National Academy of Science's lifetime fatal cancer unit risk or radon in drinking
water of 6.7 x 10 ^-\7\.
\3\ USEPA 1999j.

A second ``worst case'' evaluation was performed using four
scenarios with high radon influent levels (ranging from 1,323 pCi/L to
110,000 pCi/L) and/or high flows to further determine whether
individuals living near water treatment plants would experience
significant increases in cancer risks due to radon off-gas emissions.
For this analysis, the MINEDOSE model was used in conjunction with
radon emissions estimates to estimate lifetime fatal cancer risks for
individuals living near the modeled facility. Emissions were estimated
using MINDOSE 1.0 (1989), a predecessor to COMPLY-R (1.2), which can be
downloaded from the EPA homepage (http://www.epa.gov/rpdweb00/
assessment/comply.html). Comply-R (1.2, radon-specific) is intended for
demonstrating compliance with the National Emissions Standards for
Hazardous Air Pollutants (NESHAPS) in 40 CFR 61, Subpart B, which are
the Federal standards for radon emissions from underground uranium
mines. While these standards do not apply to drinking water facilities,
the model can be used to estimate radon exposures from aeration vents
at drinking water facilities. To check for consistency between MINEDOSE
and COMPLY-R, several modeling scenarios done in the original analysis
with MINEDOSE were repeated using COMPLY-R and the results from
MINEDOSE were found to be conservative with respect to the COMPLY-R
results, i.e., COMPLY-R predicts lower exposures for the scenarios
modeled. The MINEDOSE code was originally used instead of the AIRDOS
code because of its relative ease of use. When modeling the same
scenarios with MINEDOSE and AIRDOS, the predicted exposures were
determined to be similar enough to warrant the use of MINEDOSE for this
work. The results from the MINEDOSE modeling work and subsequent work
(USEPA 1994a) concluded that even these ``worst case maximum individual
risks'' from radon off-gas were much smaller (300 to 1,000 times
smaller) than the average individual risks posed by the untreated
water.
(ii) Permitting of Radon Off-Gas from Drinking Water Facilities.
Radon emissions to ambient air are only Federally regulated under 40
CFR 61,

[[Page 59291]]

National Emission Standards for Hazardous Air Pollutants (NESHAPs).
These regulations apply to radon emissions under very specific
circumstances, including emissions of radon to ambient air from uranium
mine tailings, phosphogypsum stacks (40 CFR 61, Subpart R), Department
of Energy storage and disposal facilities for radium-containing
materials (40 CFR 61, Subpart Q), and underground uranium mines (40 CFR
61, Subpart B). At present, there are no State or Federal regulations
that directly apply to radon air emissions from water treatment
facilities.
To assess potential procedures (e.g., permit applications, off-gas
risk modeling) and costs that could be associated with radon off-gas
from aeration facilities, EPA gathered information from agencies
responsible for air permitting (USEPA 1999h), using California as a
case study. California air permitting requirements are expected to be
more restrictive than most States, and for this reason, it is
considered a conservative case study. The information gathered is not
expected to be nationally representative, but is illustrative as a
``worst case scenario''.
EPA contacted representatives from nine air districts in California
via telephone to determine the likely response of their district to
promulgation of a radon rule with an associated radon MCL requirement
(USEPA 1999h). The air boards were chosen to represent large,
metropolitan areas, medium-sized cities, and smaller, more rural areas.
The representatives responded to the following questions:
What is the likely response of your permitting board to
water systems installing aeration treatment to comply with the radon
rule?
What are the likely permitting procedures and costs for
water systems installing aeration for radon? Who would be responsible,
the permitting board or the water system, for carrying out each
procedure and paying the costs?
Will large water systems and small water systems follow
different procedures, or are procedures uniform regardless of water
system size (e.g., off-gas volume)? How do permitting costs change with
the applicant's system size?
Will water systems be required to perform off-gas risk
modeling as part of the permitting procedure or will they be required
to do other environmental impact analyses?
Would there be annual renewal procedures (e.g.,
reapplication, compliance monitoring) and costs? Who would be
responsible for carrying our the procedures and bearing the costs?
Is ongoing monitoring likely to be required?
Where possible, representatives provided estimates of time and cost
that could be incurred by water systems and the districts as a result
of the potential district response to the radon rule.
Responses to these questions indicated that the likely response to
a radon rule is similar across the California air districts contacted.
Most districts indicated they are likely to follow the lead of the
State. ``Following the State's lead'' means that, if the State includes
radon on its Toxic Air Contaminants List and establishes potency
factors (unit risk factors and expected exposure levels for radon), air
districts will probably regulate drinking water system aeration
facilities through permits. Permitting procedures are similar across
air districts and generally do not vary for facilities of different
sizes. However, permitting costs and who bears those costs can vary
significantly from air district to air district. Some portion of the
costs are likely to vary based on facility size or emissions level.
Currently, ``radionuclides'' (which includes radon) are on the
Toxic Air Contaminant Identification List developed by the California
Air Resources Board. Listed contaminants are categorized by priority,
and depending on what category a substance is in, the substance may or
may not have ``potency factors'' developed by California's Office of
Environmental Hazard Health Assessment (OEHHA). At the present time,
radon is ``Category 4A'', which means that OEHHA is not currently
planning on publishing values for the radon unit risk factor and
reference exposure level, indicating that air boards are not likely to
require permitting for radon off-gas at the present time. However,
radon has been proposed for elevation in priority to ``Category 3'',
which means that it could be a candidate for the development potency
numbers in the future. Since California air quality districts generally
follow the lead of OEHHA, if OEHHA publishes a unit risk factor and
reference exposure level for radon in the future, air districts are
then likely to evaluate whether radon should be considered in their air
permitting programs. If OEHHA decides not to establish potency factors
for radon, California air districts are not likely to require
permitting for radon off-gas from drinking water treatment plants.
Respondents indicated that typical permitting procedures were: a
system applies for a permit to construct; the board evaluates the
application and decides whether or not to issue a permit; a permit may
then be issued, after which the system may construct the aerator; the
District conducts an inspection and the system may or may not have to
perform testing; a public notice is issued if required by risk level
and proximity of schools; the District issues a permit to operate;
system must annually renew the permit (no monitoring or inspection
likely). It is likely that water systems in the more densely populated,
Metropolitan areas are more likely to need to do a risk assessment and
perform modeling as part of their permit application. Permitting costs
ranged from < $500 for simple permitting up to $50,000 for more
complicated situations, with typical permitting costs reported in the
$1,000 to $5,000 range. These costs do not include any radon dispersion
controls or other engineering controls that might be required for the
permit.
(b) Centralized Liquid Phase Granular Activated Carbon (GAC) and
Point-of-Entry GAC. GAC removes radon from water via sorption.
``Downflow'' designs are used, in which the raw water is introduced at
the top of the carbon bed and flows under pressure downwards through
the bed. The treated water may then be disinfected or otherwise post-
treated and piped to the distribution system. Advantages to the use of
GAC relative to aeration include the lack of a need to break pressure
(and hence re-pump), the lack of radon off-gas emissions, and, in very
small systems applications with good water quality, GAC typically has
no moving parts and requires little maintenance. Details regarding the
process of radon removal via GAC are provided elsewhere (USEPA 1999h,
AWWARF 1998a,b). This discussion will focus on potential issues that
small water systems may face if they choose GAC for radon removal. Of
these, raw water quality is of paramount concern since it affects radon
removal efficiency, unit lifetime, and the potential for secondary
radiation hazards. Radon, iron, uranium, and radium levels are most
important.
(i) Radon Influent Levels for POE GAC: Gamma Radiation Hazards. An
upper limit of 5,000 pCi/L of radon in influent water being treated by
POE GAC is suggested by Rydell et al. (1989) and Kinner et al. (1990b)
to protect persons in frequent proximity to the carbon bed (i.e.,
residents) from gamma ray exposures. This influent level is based on a
residential exposure limit of 170 mRem/year, or 0.058 mR/hour based on
8 hours/day of maximum exposure, 365 days per year. The 170 mRem/year
limit was established by the National Council on Radiation

[[Page 59292]]

Protection Bulletin (cited by Rydell et al. 1989). Note that this
residential exposure limit is less conservative than the EPA
recommended limit of 100 mRem/year for water treatment plant personnel.
However, the assumption of 8 hours/day of maximum proximity is
extremely conservative. The 100 mRem/year limit is achieved if a person
gets maximum exposure for approximately 5 hours per day or less, 365
days per year, which is still a conservative assumption.
Rydell et al. determined this influent limit based on an empirical
and theoretical relationship between radon influent level and gamma ray
emissions from the carbon bed. As will be discussed next, based on
recent work using improved gamma ray detection methodology, Hess et al.
(1998) report that this limit may be too low by a factor of 2, i.e.,
the suggested radon influent limit may be closer to 10,000 pCi/L. Note
that these limits are based on assumptions about GAC contact basin
configurations, type and extent of shielding, length of time and
proximity of persons to the unit, etc. While the ``rules-of-thumb''
described previously are useful, appropriate radon influent limits may
be higher or lower depending upon site-specific considerations and
should be determined on a case-by-case basis.
The University of Maine reported results on the removal of radon
from drinking water using GAC (Hess et al. 1998). Nine carbon beds (all
in Maine), which had been in use for more than 10 years by public water
systems and private homes for radon removal, were studied. Radon
influent levels ranged from 330 to 107,000 pCi/L, with a mean of 24,500
pCi/L and a standard deviation of 11,800 pCi/L. Gamma ray emissions
from the GAC units and accumulated radon progeny, uranium, and radium
were analyzed. Gamma ray emissions from the GAC surface ranged from
11.5 uR/h to 301 uR/h, with a mean of 78 uR/h and a standard deviation
of 82 uR/h, and were 2 to 4 times lower than predicted by theory. The
authors concluded that the limit of 5,000 pCi/L suggested by Rydell et
al. (1989) may be too low by a factor of 2 or more.
(ii) Radon Influent Levels for Centralized GAC: Gamma Radiation
Hazards. Using the very conservative assumption that a water treatment
operator will be in close proximity for 40 hours per week, the 100
mRem/year translates to around 0.05 mR/hour, which also corresponds to
a maximum of 5,000-10,000 pCi/L of radon for small flows. However,
since GAC is likely to be used only by very small water systems and
does not involve intensive O&M, much shorter work weeks are likely.
Using 10 hours/week, the maximum radon influent level would be higher.
Again, these are ``rule-of-thumb'' suggestions only. The best means to
ensure that 100 mRem/year maximum exposure limits are maintained is to
implement appropriate monitoring of gamma levels in the treatment
facility and to ensure that proper shielding and worker proximity
restraints are engineered to minimize exposures.
(iii) Other Water Quality Considerations: Naturally-Occurring Iron
and Dissolved Organic Materials. The adsorption of iron precipitates
can reduce a unit's radon removal efficiency, so that the raw water may
need to be pre-treated to stabilize and/or remove the dissolved iron.
The American Water Works Association Research Foundation (AWWARF
1998a,b) reports that waters with low iron and low levels of naturally
occurring organic matter (``total organic carbon'', TOC) can achieve
good radon steady-state removals (i.e., radon sorption equals radon
decay), but that the negative effects of iron and TOC on removal
efficiencies may necessitate pilot testing to ensure proper contactor
design. For raw water with high iron and/or TOC, pre-filtration or pre-
oxidation/filtration may be required to achieve good steady-state
removals.
(iv) Other Water Quality Considerations: Naturally-Occurring
Uranium and Radium: Uranium and radium raw water levels are also of
concern since sorption may occur onto the GAC surface, which results in
uranium and radium occurrence in the GAC filter backwash residuals and
ultimately may create a final GAC bed disposal problem. Water quality
(pH, iron levels, natural organic matter levels, alkalinity, etc.)
determine the extent to which uranium and radium sorb to the GAC
surface. AWWARF (1998b) reported results from case studies conducted
over a two year period in New Hampshire, New Jersey, and Colorado,
including findings regarding loadings of uranium and radium on the GAC
surface and respective levels in backwash residuals. Radon influent
levels were 15,000-17,000 pCi/L, 2,220 pCi/L, and <7,500 pCi/L at the
New Hampshire, New Jersey, and Colorado sites, respectively. In the New
Hampshire pilot study, backwash residuals contained 200
pCi/g uranium and 50 to 60 pCi/g radium. For water
treatment residuals with uranium levels between 75 and 750 pCi/g, EPA
suggests that disposal measures be determined on a case-by-case basis
(USEPA 1994b). In general, disposal in a controlled landfill
environment may be necessary. The GAC bed itself accumulated less than
the limit of 75 pCi/g for all but one of the five GAC columns in New
Hampshire. For the New Jersey and Colorado pilot plants, uranium,
radium, and radon progeny levels were low enough in the backwash
residuals and the GAC bed that special disposal considerations were not
an issue. It should be noted that State disposal restrictions may be
more stringent than EPA's suggestions, which may make GAC a less
attractive alternative in these States.
(v) GAC Disposal Issues. Radon progeny (e.g., Pb-210, a beta
emitter) accumulation is also related to radon influent level. If radon
influent levels are high, the GAC unit lifetime may decrease
significantly, where this lifetime is defined as the length of time
between start-up and when an unacceptable accumulation of radioactive
Pb-210 occurs. While no Federal agency currently has the legislative
authority to regulate the disposal of wastes generated by water
treatment facilities on the basis of naturally occurring radioactive
materials (NORM), EPA (USEPA 1994b) suggests that NORM solid wastes
with radioactivity above 2,000 pCi/g be disposed of in appropriate low-
level radioactive waste facilities. Furthermore, given the prohibitive
expense and burden of disposing of low-level radioactive waste, EPA
would suggest that water treatment facilities avoid situations where
such high waste levels would expected to potentially occur. In the case
of wastes containing Pb-210, EPA suggests that case-by-case
determinations be made for determining appropriate disposal. In
summary, for higher radon influent levels, shorter bed lifetimes may be
appropriate to reduce Pb-210 build-up.
Hess et al. (1998), cited previously, also studied several methods
of cleaning the GAC bed by removing Pb-210 and radium from the spent
GAC with various chemical cleaning solutions (e.g., solutions of
hydrochloric acid, nitric acid, sodium hydroxide, etc.). Disposal of
the cleaned GAC and the much smaller volume of concentrated radon
progeny and radium is expected to be cheaper in some cases than
disposal of the contaminated GAC bed to a controlled disposal-facility.
The authors concluded that several of the cleaning solutions
(hydrochloric acid at 1 mole/liter, nitric acid at 0.5 mole/liter, and
acetic acid 0.5 mole/liter in quantities of 150 mL solution per 100
grams of carbon) show promise. Precipitates on the GAC surface
(including iron oxides, sorbed radium

[[Page 59293]]

and radon progeny, including Pb-210) were effectively removed. Removal
efficiencies for Pb-210 ranged from 30 percent to 70 percent and radium
removals from 70 to 90 percent. This work indicates that a viable
system of collecting and cleaning spent GAC material may be feasible,
potentially making GAC a more attractive small systems alternative.
Work supporting programs of this type deserves further consideration.
(vi) The American Water Works Association Research Foundation
Report on Radon Removal Using GAC. The American Water Works Association
Research Foundation (AWWARF 1998a,b) has recently reported on radon
removal by GAC. AWWARF suggests that water systems with design flows
below 70 gallons per minute may want to evaluate GAC and POE GAC as
potential radon removal technologies (AWWARF 1999a), but warns that
they appear to be attractive technologies only for very small systems
with radon influent levels below 5,000 pCi/L, iron and manganese levels
low enough not to warrant pre-treatment, and uranium and radium levels
low enough not to accumulate to levels of concern on the GAC bed (USEPA
1994b). These findings are generally consistent with EPA's findings.

B. Analytical Methods

1. Background
The SDWA directs EPA to set a contaminant's MCL as close to its
MCLG as is ``feasible'', the definition of which includes an evaluation
of the feasibility of performing chemical analysis of the contaminant
at standard drinking water laboratories. Specifically, SDWA directs EPA
to determine that it is economically and technologically feasible to
ascertain the level of the contaminant being regulated in water in
public water systems (Section 1401(1)(C)(i)). NPDWRs are also to
contain ``criteria and procedures to assure a supply of drinking water
which dependably complies with such [MCLs]; including accepted methods
for quality control and testing procedures to insure compliance with
such levels. * * *'' (Section 1401(1)(D)).
To comply with these requirements, EPA considers method performance
under relevant laboratory conditions, their likely prevalence in
certified drinking water laboratories, and the associated analytical
costs. A critical part of the method performance evaluation involves an
analysis of inter-laboratory collaborative study data. This analysis
allows EPA to confirm that the method provides reliable and repeatable
results when used within a given laboratory and when used
``identically'' in other standard laboratories. Other technical
limitations, e.g., sampling and sample preservation requirements,
requirements for non-standard apparatus, and hazards from wastestreams,
are also considered.
In particular, the reliability of analytical methods at the maximum
contaminant level is critical to the implementation and enforcement of
the NPDWR. Therefore, each analytical method considered was evaluated
for accuracy, recovery (lack of bias), and precision (good
reproducibility over the range of MCLs considered). The primary purpose
of this evaluation is to determine:
Whether currently available analytical methods measure
radon in drinking water with adequate accuracy, bias, and precision;
If any newly developed analytical methods can measure
radon in drinking water with acceptable performance;
Reasonable expectations of technical performance for these
methods by analytical laboratories conducting routine analysis at or
near the MCL levels (interlaboratory studies); and
Analytical costs. The selection of analytical methods for
compliance with the proposed regulation includes consideration of the
following factors:
(a) Reliability (i.e., Precision/ accuracy of the analytical
results over a range of concentrations, including the MCL);
(b) Specificity in the presence of interferences;
(c) Availability of adequate equipment and trained personnel to
implement a national compliance monitoring program (i.e., laboratory
availability);
(d) Rapidity of analysis to permit routine use; and
(e) Cost of analysis to water supply systems.
2. Analytical Methods for Radon in Drinking Water
(a) Proposed Analytical Methods for Radon. The analytical methods
described here are the testing procedures EPA identified and evaluated
to insure compliance with the MCL and AMCL. Two analytical methods for
radon in water that fit EPA's criteria for acceptability as compliance
monitoring methods were identified: Liquid Scintillation Counting (LSC)
and the de-emanation method. The LSC method is here defined as Standard
Method 7500-Rn, SM 1995; the de-emanation method is described in the
report, ``Two Test Procedures for Radon in Drinking Water,
Interlaboratory Study'' (USEPA 1987). EPA believes these methods are
technically sound, economical, and generally available for radon
monitoring, and is proposing their use for monitoring to determine
compliance with the MCL or AMCL. The reliability of these methods has
been demonstrated by a history of many years of use by State, Federal,
and private laboratories. Both methods have undergone interlaboratory
collaborative studies (multi-laboratory testing), demonstrating
acceptable accuracy and precision. Thirty-six laboratories participated
in the interlaboratory study for Standard Method 7500-Rn and sixteen
labs in the de-emanation study. The American Society for Testing and
Materials (ASTM) has also published an LSC method (ASTM 1992). Although
its collaborative study (15 participating laboratories) was conducted
at radon sample concentrations greater than 1,500 pCi/L, it is
substantially equivalent to Standard Method (SM) 7500-Rn. EPA is
proposing that ASTM D-5072-92 serve as an alternate method for radon
for both the MCL and AMCL, under the restriction that the quality
controls from SM 7500-Rn are met; namely, that the relative percent
differences between duplicate analyses are less than the 95 percent
confidence level counting uncertainty, as defined in SM 7500-Rn. Table
VIII.B.1 summarizes the proposed analytical methods for radon in
drinking water.

[[Page 59294]]

Table VIII.B.1.--Proposed Analytical Methods for Radon in Drinking Water
----------------------------------------------------------------------------------------------------------------
References (method or page number)
Method -----------------------------------------------------------------
SM ASTM EPA
----------------------------------------------------------------------------------------------------------------
Liquid Scintillation Counting................. 7500-Rn\1\ D 5072-92 ......................................
\2\
De-emanation.................................. ........... ........... EPA 1987 \3\
----------------------------------------------------------------------------------------------------------------
Notes:
\1\ Standard Methods for the Examination of Water and Wastewater. 19th Edition Supplement. Clesceri, L., A.
Eaton, A. Greenberg, and M. Franson, eds. American Public Health Association, American Water Works
Association, and Water Environment Federation. Washington, DC. 1996.
\2\ American Society for Testing and Materials (ASTM). Standard Test Method for Radon in Drinking Water.
Designation: D 5072-92. Annual Book of ASTM Standards. Vol. 11.02. 1996.
\3\ Appendix D, Analytical Test Procedure, ``The Determination of Radon in Drinking Water''. In ``Two Test
Procedures for Radon in Drinking Water, Interlaboratory Collaborative Study''. EPA/600/2-87/082. March 1987.
p. 22.

Other analytical methods were evaluated, but they failed at least
one of the criteria described previously. These methods included an
``activated charcoal passive radon collector'', a ``de-gassing Lucas
Cell'' technique (a variant of the de-emanation method), the ``electret
ionization chamber system'', and a ``delay-coincidence liquid
scintillation counting system''. All of these methods are described and
evaluated elsewhere (USEPA 1999g). As described next, if EPA implements
the ``Performance Based Measurement System'' (PBMS) program, then any
method that performs according to specified criteria may be used for
compliance monitoring.
(b) Summary of Methods. Analysis of radon in drinking water by the
LSC method involves preparation of the water sample (ca. 20 mL), which
includes the selective partitioning of radon from the water sample into
a water-immiscible mineral-oil scintillation cocktail and allowance for
equilibration of radon-222 with its progeny. The prepared sample is
then analyzed with an alpha-particle counting system that is optimized
for detecting radon alpha particles. Scintillation counting methods are
discussed later. One of the advantages of transferring the radon from
the water sample into the water-immiscible cocktail is that potential
interferents (other alpha emitters) are left behind in the water phase.
The de-emanation method involves bubbling radon-free helium or aged
air (low background radon) through the water sample into an evacuated
scintillation chamber. After equilibrium is reached (3 to 4 hours),
this chamber is placed in a counter and the resulting scintillations
are counted. This method generally allows measurement of lower level of
radon than does low volume direct liquid scintillation. However, this
method is more difficult to use, requiring specialized glassware and
skilled technicians. Regions of the country with high radon levels in
water (e.g., New Hampshire and Maine) may experience problems with this
method, since the high radon levels in the samples can cause high
backgrounds in the Lucas cell, forcing retirement of the cell for
extended periods.
(c) Alpha Particle Counting Methods for Radon-222. One of the
distinct characteristics of alpha particles is that they exhibit an
intense loss of energy as they pass through matter, due to strong
interactions between the alpha particles and the surrounding atoms.
This intense loss of energy is used in differentiating alpha
radioactivity from other types. Some of the alpha particle's energy
loss is due to its ionization of atoms with which it comes in contact.
Alpha particle detection is based on this phenomenon: when alpha
particles ionize the phosphor coating of a detector, the energized
phosphor ``scintillates'' (or emits light). The resulting light (or
scintillations) are then detected and quantified with an appropriate
detector that is calibrated to determine the concentration of the alpha
emitter of interest. There are variants of detectors that measure these
interactions, but this discussion will focus on the type relevant to
the LSC and Lucas Cell methods.
In scintillation counting, the alpha particle transfers energy to a
scintillator medium, e.g., a phosphor dissolved in a solvent
``cocktail'', which is enclosed within a ``light-tight'' container to
reduce background light. The scintillation cocktail serves two roles:
it contains the phosphor which is involved in quantifying the radon
activity (concentration) and it selectively extracts the radon from the
water sample, leaving behind other alpha emitters that may interfere
with the analysis. The transfer of energy from the radon-derived alpha
particles to the phosphor dissolved in the scintillator medium results
in the production of light (scintillation) of energies characteristic
of the phosphor and with an intensity proportional to the energy
transmitted from the alpha particles, which are the ``signature'' of
radon-222. A ``counter'' records the individual amplified pulses which
are proportional to the number of alpha particles striking the
scintillation detector, which is ultimately proportional to the radon
activity in the original sample. The scintillation cell system used for
the liquid scintillation method is as described previously. The system
used for the de-emanation method is similar, with the exception that a
scintillation flask (``Lucas Cell'', a 100-125 ml metal cup coated on
the inside with a zinc sulfide phosphor and having a transparent
window) replaces the liquid scintillation medium described. A counting
system compatible with the scintillation flask is incorporated to
quantify the radon concentration in the sample. Since radon has a short
decay period (half-life of 3.8 days), correction methods are employed
to account for the radon that decayed between the time of sample
collection and the end of the analysis.
(d) Sampling Collection, Handling, and Preservation. In order to
ensure that samples arriving at laboratories for analysis are in good
condition, EPA is proposing requirements for sample collection,
handling and preservation.
When sampling for dissolved gases like radon, special attention to
sample collection is required. Either the sample collection method
described in SM 7500-Rn, the VOC sample collection method, or one of
the methods described in ``Two Test Procedures for Radon in Drinking
Water, Interlaboratory Collaborative Study'' (USEPA 1987) should be
used. In addition, because dissolved radon tends to accumulate at the
interface between a water sample and some types of plastic containers,
glass bottles with teflon lined caps must be used. Finally, EPA's
assessment of laboratory performance is premised on the assumption that
sample analysis occurs no later than 4 days after collection.
Laboratories unable to comply with this holding time limit may have
difficulty performing within the estimated precision and accuracy
bounds. EPA solicits public comment on the proposed sample collection
procedures for radon in drinking water.

[[Continued on page 59295]]

Notices For
2009
2008
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994

National Primary Drinking Water Regulations; Radon-222

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