[Federal Register Volume 79, Number 204 (Wednesday, October 22, 2014)]
[Proposed Rules]
[Pages 63257-63286]
[FR Doc No: 2014-24347]

Vol. 79

Wednesday,

No. 204

October 22, 2014

Part III

 Environmental Protection Agency

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40 CFR Parts 403 and 441

 Effluent Limitations Guidelines and Standards for the Dental Category;
Proposed Rule

Federal Register / Vol. 79 , No. 204 / Wednesday, October 22, 2014 /
Proposed Rules

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 403 and 441

[EPA-HQ-OW-2014-0693; FRL-9911-63-OW]
RIN 2040-AF26

Effluent Limitations Guidelines and Standards for the Dental
Category

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: EPA is proposing technology-based pretreatment standards under
the Clean Water Act (CWA) for discharges of pollutants into publicly
owned treatment works (POTWs) from existing and new dental practices
that discharge dental amalgam. Dental amalgam contains mercury in a
highly concentrated form that is relatively easy to collect and
recycle. Dental offices are the main source of mercury discharges to
POTWs. Mercury is a persistent and bioaccumulative pollutant in the
environment with well-documented neurotoxic effects on humans. Mercury
pollution is widespread and comes from many diverse sources such as air
deposition from municipal and industrial incinerators and combustion of
fossil fuels. Mercury easily becomes diffuse in the environment and
mercury pollution is a global problem. Removing mercury from the waste
stream when it is in a concentrated and easy to handle form like in
waste dental amalgam is an important and commonsense step to take to
prevent that mercury from being released back into the environment
where it can become diffuse and a hazard to humans.
    The proposal would require dental practices to comply with
requirements for controlling the discharge of mercury and other metals
in dental amalgam into POTWs based on the best available technology or
best available demonstrated control technology. Specifically, the
requirements would be based on the use of amalgam separators and best
management practices (BMPs). Amalgam separators are a practical,
affordable and readily available technology for capturing mercury and
other metals before they are discharged into sewers and POTWs. EPA is
also proposing to amend selected parts of the General Pretreatment
Regulations to streamline oversight requirements for the dental sector.
EPA expects compliance with this proposed rule would reduce the
discharge of metals to POTWs by at least 8.8 tons per year, about half
of which is mercury. EPA estimates the annual cost of the proposed rule
would be $44 to $49 million.

DATES: Comments on this proposed rule must be received on or before
December 22, 2014. Under the Paperwork Reduction Act (PRA), comments on
the information collection provisions must be received by the Office of
Management and Budget (OMB) on or before November 21, 2014. EPA will
conduct a public hearing on November 10, 2014 at 1 p.m. in the William
J. Clinton Building--East Room 1153, 1201 Constitution Avenue NW.,
Washington, DC.

ADDRESSES: Submit your comments, identified by docket identification
(ID) number EPA-HQ-OW-2014-0693 by one of the following methods:
     http://www.regulations.gov: Follow the on-line
instructions for submitting comments.
     Email<EMAIL_ADDRESS>Attention Docket ID number EPA-
HQ-OW-2014-0693.
     Mail: Water Docket, Environmental Protection Agency, Mail
code: 4203M, 1200 Pennsylvania Ave. NW., Washington, DC 20460.
Attention Docket ID number EPA-HQ-OW-2014-0693. Please include a total
of three copies. In addition, please mail a copy of your comments on
the information collection provisions to the Office of Information and
Regulatory Affairs, OMB, Attn: Desk Officer for EPA, 725 17th St. NW.,
Washington, DC 20503.
     Hand Delivery: Water Docket, EPA Docket Center, EPA West
Building Room 3334, 1301 Constitution Ave. NW., Washington, DC,
Attention Docket ID Number EPA-HQ-OW-2014-0693. Such deliveries are
only accepted during the Docket's normal hours of operation, and
special arrangements should be made for deliveries of boxed information
by calling<PHONE_NUMBER>.
    Instructions: Direct your comments to docket ID number EPA-HQ-OW-
2014-0693. EPA's policy is that all comments received will be included
in the public docket without change and may be made available online at
http://www.regulations.gov, including any personal information
provided, unless the comment includes information claimed to be
Confidential Business Information (CBI) or other information whose
disclosure is restricted by statute. Do not submit information that you
consider to be CBI or otherwise protected through www.regulations.gov
or email. The http://www.regulations.gov Web site is an ``anonymous
access'' system, which means EPA will not know your identity or contact
information unless you provide it in the body of your comment. If you
send an email comment directly to EPA without going through http://www.regulations.gov your email address will be automatically captured
and included as part of the comment that is placed in the public docket
and made available on the Internet. If you submit an electronic
comment, EPA recommends that you include your name and other contact
information in the body of your comment and with any disk or CD-ROM you
submit. If EPA cannot read your comment due to technical difficulties
and cannot contact you for clarification, EPA may not be able to
consider your comment. Electronic files should avoid the use of special
characters, any form of encryption, and be free of any defects or
viruses.
    Docket: All documents in the docket are listed in the http://www.regulations.gov index. A detailed record index, organized by
subject, is available on EPA's Web site at http://water.epa.gov/scitech/wastetech/guide/dental/index.cfm. Although listed in the index,
some information is not publicly available, e.g., CBI or other
information whose disclosure is restricted by statute. Certain other
material, such as copyrighted material, will be publicly available only
in hard copy. Publicly available docket materials are available either
electronically in http://www.regulations.gov or in hard copy at the
Water Docket in the EPA Docket Center, EPA/DC, EPA West William
Jefferson Clinton Bldg., Room 3334, 1301 Constitution Ave. NW.,
Washington, DC. The Public Reading Room is open from 8:30 a.m. to 4:30
p.m., Monday through Friday, excluding legal holidays. The telephone
number for the Public Reading Room is<PHONE_NUMBER>, and the telephone
number for the Water Docket is<PHONE_NUMBER>.
    Pretreatment Hearing Information: EPA will conduct a public hearing
on the proposed pretreatment standards on November 10, 2014 at 1:00
p.m. in the William Jefferson Clinton Building EPA East Building--East
Room 1153, 1201 Constitution Avenue NW., Washington, DC. No
registration is required for this public hearing. During the
pretreatment hearing, the public will have an opportunity to provide
oral comment to EPA on the proposed pretreatment standards. EPA will
not address any issues raised during the hearing at that time but these
comments will be included in the public record for the rule. For
security reasons, we request that you bring photo identification with
you to the meeting. Also, if you let us know in advance of your plans
to attend, it will expedite the process of

signing in. Seating will be provided on a first-come, first-served
basis. Please note that parking is very limited in downtown Washington,
and use of public transit is recommended. The EPA Headquarters complex
is located near the Federal Triangle Metro station. Upon exiting the
Metro station, walk east to 12th Street. On 12th Street, walk south to
Constitution Avenue. At the corner, turn right onto Constitution Avenue
and proceed to the EPA East Building entrance.

FOR FURTHER INFORMATION CONTACT: Damon Highsmith, Engineering and
Analysis Division (4303T), Office of Water, Environmental Protection
Agency, 1200 Pennsylvania Ave. NW., Washington, DC 20460-0001;
telephone:<PHONE_NUMBER>; email<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:

Table of Contents

I. Regulated Entities
II. How To Submit Comments
III. Supporting Documentation
IV. Overview
V. Legal Authority
VI. Purpose and Summary of Proposed Rule
VII. Solicitation of Data and Comments
VIII. Background
IX. Description of the Dental Industry
X. Summary of Data Collection
XI. Wastewater Characteristics, Dental Office Configurations, and
Technology Options
XII. Scope/Applicability
XIII. Subcategorization
XIV. Proposed Regulation
XV. Technology Costs
XVI. Economic Impact Analysis
XVII. Pollutant Reductions to POTWs and Surface Waters
XVIII. Cost Effectiveness
XIX. Environmental Assessment
XX. Non-Water Quality Environmental Impacts Associated With the
Proposed Technology Basis
XXI. Implementation and Proposed Changes to General Pretreatment
Regulations in 40 CFR Part 403
XXII. Statutory and Executive Order Reviews

I. Regulated Entities

    Entities potentially regulated by this action include:
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    \1\ See Section XXI for a definition of Control Authority.

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                                                         North American
                                                            Industry
           Category              Example of regulated    Classification
                                        entity           System (NAICS)
                                                              code
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Industry......................  A general dentistry               621210
                                 practice or large
                                 dental facility
                                 where mercury
                                 amalgam is placed or
                                 removed.
States........................  Where they are the                221320
                                 Control Authority
                                 \1\.
Municipalities................  POTWs and other                   221320
                                 municipally owned
                                 facilities that
                                 receive pollutants
                                 from dental offices.
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    This section is not intended to be exhaustive, but rather provides
a guide for readers regarding entities likely to be regulated by this
proposed action. Other types of entities that do not meet the above
criteria could also be regulated. To determine whether your facility
would be regulated by this proposed action, you should carefully
examine the applicability criteria listed in Sec.  441.10 and the
definitions in Sec.  441.20 of this proposed rule and detailed further
in Section XII of this preamble. If you still have questions regarding
the proposed applicability of this action to a particular entity,
consult the person listed under FOR FURTHER INFORMATION CONTACT.

II. How To Submit Comments

    The public may submit comments in written or electronic form. (see
ADDRESSES). Electronic comments must be identified by the docket ID
number EPA-HQ-OW-2014-0693 and must be submitted as a WordPerfect, MS
Word or ASCII text file, avoiding the use of special characters and any
form of encryption. EPA requests that any graphics included in
electronic comments also be provided in hard-copy form. EPA also will
accept comments and data on disks in the aforementioned file formats.
Electronic comments received on this document may be filed online at
many Federal Depository Libraries. No CBI should be sent by email.

III. Supporting Documentation

    The proposed rule is supported by a number of documents including:
     Technical and Economic Development Document for Proposed
Effluent Limitations Guidelines and Standards for the Dental Category
(TEDD), Document No. EPA-821-R-14-006.
    The TEDD summarizes the technical and economic analysis described
in this document. The TEDD and additional records are available in the
public record for this proposed rule and on EPA's Web site at http://water.epa.gov/scitech/wastetech/guide/dental/index.cfm. They are
available in hard copy from the National Service Center for
Environmental Publications (NSCEP), U.S. EPA/NSCEP, P.O. Box 42419,
Cincinnati, Ohio 45242-2419, telephone<PHONE_NUMBER>, http://epa.gov/ncepihom.

IV. Overview

    The preamble describes the terms, acronyms, and abbreviations used
in this document; the background documents that support these proposed
regulations; the legal authority for the proposed rules; a summary of
the options considered for the proposal; background information; and
the technical and economic methodologies used by the Agency to develop
these proposed regulations. This preamble also solicits comment and
data on specific areas of interest.

V. Legal Authority

    EPA is proposing this regulation under the authorities of sections
101, 301, 304, 306, 307, 308, and 501 of the CWA, 33 U.S.C. 1251, 1311,
1314, 1316, 1317, 1318, 1342 and 1361 and pursuant to the Pollution
Prevention Act of 1990, 42 U.S.C. 13101 et seq.

VI. Purpose and Summary of Proposed Rule

    Across the United States, many states and POTWs (also referred to
as municipal wastewater treatment plants) are working toward the goal
of reducing discharges of mercury to POTWs. Mercury is a persistent and
bioaccumulative pollutant with well-documented effects on human health.
On November 6, 2013, the United States joined the Minamata Convention
on Mercury, a new multilateral environmental agreement not yet in force
that addresses specific human activities that are contributing to
widespread mercury pollution. The agreement identifies dental amalgam
as a mercury-added product for which certain measures should be taken.
Specifically, the Convention lists nine

measures for phasing down the use of mercury in dental amalgam,
including promoting the use of best environmental practices in dental
facilities to reduce releases of mercury and mercury compounds to water
and land. Nations that are parties to the Convention are required to
implement at least two of the nine measures to address dental amalgam.
    Many studies have been conducted in an attempt to identify the
sources of mercury entering POTWs. According to the 2002 Mercury Source
Control and Pollution Prevention Program Final Report (DCN DA00006)
prepared by the National Association of Clean Water Agencies (NACWA),
dentists are the main source of mercury discharges to POTWs. A study
funded by the American Dental Association (ADA) published in 2005
estimated that 50% of mercury entering POTWs was contributed by dental
offices (DCN DA00163). Mercury is discharged in the form of dental
amalgam when dentists remove old amalgam fillings from cavities, and
from excess amalgam removed when a dentist places a new filling.
    EPA estimates that across the United States 4.4 tons of mercury
from waste dental amalgam are collectively discharged into POTWs
annually. Mercury at POTWs frequently partitions to the sludge, the
solid material that remains after wastewater is treated. Mercury from
amalgam can then make its way into the environment through the
incineration, landfilling, or land application of sludge or through
surface water discharge. Once deposited, certain microorganisms can
change mercury into methylmercury, a highly toxic form of mercury that
accumulates in fish, shellfish, and animals that eat fish. Fish and
shellfish are the main sources of methylmercury exposure to humans.
    Today's proposed pretreatment standards would control mercury
discharges to POTWs by requiring dentists to reduce their discharge of
dental amalgam to a level achievable through the use of the best
available technology (a combination of amalgam separators and the use
of BMPs. In order to simplify compliance with, and enforcement of, the
numeric reduction requirements, the proposed rule would allow dentists
to demonstrate compliance through the proper use of amalgam separators
rather than through discharge monitoring. Removing concentrated sources
of mercury waste opportunistically, such as through low-cost amalgam
separators at dental offices (average annual cost per dental office:
$700 \2\), is a common sense solution to managing mercury where it is
most concentrated within the waste stream that would otherwise be
released to air, land, and water.
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    \2\ This estimate is based on the average annualized cost for
dentists that do not currently have an amalgam separator. See DCN
DA00145.
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    Additionally, EPA is proposing to amend selected parts of the
General Pretreatment Regulations (40 CFR part 403) in order to
streamline permitting and oversight requirements specific to the dental
sector. The number of dental offices that would likely be subject to
national pretreatment standards is approximately ten times the current
number of Categorical Industrial Users (CIUs). The proposed changes to
40 CFR part 403 reflect EPA's recognition that the current regulatory
framework needs to be adjusted for the effective implementation and
enforcement of these pretreatment requirements affecting the dental
industry. When categorical pretreatment requirements apply to an
industry, it creates certain oversight requirements. While other
industries subject to categorical pretreatment requirements typically
consist of tens to hundreds of facilities, the dental industry consists
of approximately 100,000 facilities, making oversight of this large
number of facilities subject to categorical pretreatment standards much
more challenging.

VII. Solicitation of Data and Comments

    EPA solicits comments on the proposed rule, including EPA's
rationale as described in this preamble. EPA seeks comments on issues
specifically identified in this document as well as any other issues
that are not specifically addressed in this document. Comments are most
helpful when accompanied by specific examples and supporting data.
Specifically, EPA solicits information and data on the following
topics.
    1. Data demonstrating the effectiveness of polishing, or the use of
sorbent columns after solids separation, in reducing mercury discharges
from dental offices.
    2. Data on costs, performance, affordability and availability of
polishing in combination with amalgam separators.
    3. Ways for dental offices to demonstrate compliance with this
proposed rule, and how much reporting should be required.
    4. Information on EPA's approach for addressing offices where no
dental amalgam is applied or removed, and its approach for offices that
already employ a separator (including cases where the separator was
installed as a result of a program required by a state or other
locality and where the separator has a certified removal efficiency
that is lower than 99.0%).
    5. Information on the frequency of emergency removals at dental
offices that do not routinely place or remove amalgam.
    6. EPA seeks comment on its approach for addressing offices where
no dental amalgam is placed or removed except in limited emergency
circumstances, and its approach for offices that have already installed
an amalgam separator.
    7. EPA proposes an inspection frequency of at least once per month
to ensure proper operation and maintenance of the amalgam separator.
EPA solicits comment on this frequency as well as others, and
justifications for alternative approaches.
    8. Data on the number of dentists in practices potentially subject
to this rule that do not place or remove dental amalgam and on the
number of dentists in practices excluded from the proposed rule such as
oral pathology, oral and maxillofacial radiology, oral and
maxillofacial surgery, orthodontics, periodontics, and prosthodontics.
EPA also solicits comment on its estimate of the number of dentists in
dental specialties that are not subject to this proposed rule.
    9. Other technologies not discussed in this proposed rule that have
demonstrated an ability to reduce discharges of mercury from dental
offices and their associated costs.
    10. Data regarding EPA's analysis of clinics and very large
facilities.
    11. EPA's proposed revisions to 40 CFR part 403, including
revisions to create the DIU category, and the means of evaluating
ongoing compliance for the purposes of maintaining the DIU designation.
    12. Information about mobile facilities used to treat patients. EPA
seeks information on the number, size, operation and financial
characteristics of mobile facilities that offer dental treatment.
    13. EPA's estimate of the number of large institutional practices,
including large facilities operated by the Federal Government, and the
characteristics (chair size, number of practitioners, currently
employed mercury reduction approaches, incremental cost of proposed
requirements) of these facilities.
    14. Additional information on equipment needs and costs for
starting a dental practice including information on the life of the
dental equipment.

    15. Additional information on low revenue dental offices and if
they could represent baseline closures (see discussion in Section XVI).
    16. Additional information on the location and characteristics of
low revenue dental offices ((1) single-dentist and/or part-time
businesses that provide services as a subcontractor on an independent
fee-for-service basis (2) non-profit groups, or (3) non-viable as for-
profit businesses).
    17. Information on requiring an efficiency that exceeds the ISO
standard.
    18. The proposal would greatly reduce potential requirements that
would otherwise apply to control authorities with respect to dental
dischargers. EPA solicits comments on its estimate of burden and costs
associated with these reduced requirements. In particular, EPA solicits
data from control authorities located in municipalities or states where
similar mandatory dental amalgam reduction programs exist.

VIII. Background

A. Clean Water Act

    Congress passed the Federal Water Pollution Control Act Amendments
of 1972, also known as the Clean Water Act, to ``restore and maintain
the chemical, physical, and biological integrity of the Nation's
waters.'' (33 U.S.C. 1251(a)). The CWA establishes a comprehensive
program for protecting our nation's waters. Among its core provisions,
the CWA prohibits the discharge of pollutants from a point source to
waters of the U.S. except as authorized under the CWA. Under section
402 of the CWA, EPA authorizes discharges by a National Pollutant
Discharge Elimination System (NPDES) permit. The CWA also authorizes
EPA to establish national technology-based effluent limitations
guidelines and standards (effluent guidelines or ELGs) for discharges
from different categories of point sources, such as industrial,
commercial, and public sources.
    Congress recognized that regulating only those sources that
discharge effluent directly into the nation's waters would not be
sufficient to achieve the CWA's goals. Consequently, the CWA requires
EPA to promulgate nationally-applicable pretreatment guidelines and
standards that restrict pollutant discharges from facilities that
discharge wastewater indirectly through sewers flowing to POTWs. (see
CWA sections 304(g), 307(b) and (c), 33 U.S.C. 1314(g), and 1317(b) and
(c)). National pretreatment standards are established for those
pollutants in wastewater from indirect dischargers that may pass
through, interfere with or are otherwise incompatible with POTW
operations. Generally, pretreatment standards are designed to ensure
that wastewaters from direct and indirect industrial dischargers are
subject to similar levels of treatment. In addition, POTWs are required
to implement local treatment limits applicable to their industrial
indirect dischargers to satisfy any local requirements. (see 40 CFR
403.5).
    Direct dischargers must comply with effluent limitations in NPDES
permits. Indirect dischargers, who discharge through POTWs, must comply
with pretreatment standards. Technology-based effluent limitations in
NPDES permits are derived from effluent limitations guidelines (CWA
sections 301 and 304) and new source performance standards (CWA section
306) promulgated by EPA, or based on best professional judgment where
EPA has not promulgated an applicable effluent guideline or new source
performance standard. Additional limitations based on water quality
standards (CWA sections 301(b)(1)(C) and 303) may also be included in
the permit in certain circumstances. The ELGs are established by
regulation for categories of industrial dischargers and are based on
the degree of control that can be achieved using various levels of
pollution control technology.
    EPA promulgates national effluent limitations guidelines and
standards of performance for major industrial categories for three
classes of pollutants: (1) Conventional pollutants (total suspended
solids, oil and grease, biochemical oxygen demand, fecal coliform, and
pH); (2) toxic pollutants (e.g., toxic metals such as chromium, lead,
mercury, nickel, and zinc; toxic organic pollutants such as benzene,
benzo-a-pyrene, phenol, and naphthalene) as specified in CWA section
307 and; (3) non-conventional pollutants, those pollutants that are
neither conventional nor toxic (e.g., ammonia-N, formaldehyde, and
phosphorus).

B. Effluent Guidelines and Standards Program

    Effluent limitations guidelines and standards are technology-based
regulations that are developed by EPA for a category of dischargers.
These regulations are based on the performance of control and treatment
technologies. The legislative history of CWA section 304(b), describes
the need to achieve progressively higher levels of control through
research and development of new processes, modifications, replacement
of obsolete plans and processes, and other improvements in technology,
taking into account the cost of controls. Congress also directed that
EPA not consider water quality impacts on individual water bodies as
the guidelines are developed. See Statement of Senator Muskie (Oct. 4,
1972), reprinted in Legislative History of the Water Pollution Control
Act Amendments of 1972, at 170. (U.S. Senate, Committee on Public
Works, Serial No. 93-1, January 1973.)
    There are standards applicable to direct dischargers (dischargers
to surface waters), and standards applicable to indirect dischargers
(discharges to publicly owned treatment works or POTWs). The standards
relevant to this rulemaking are summarized here.
1. Best Available Technology Economically Achievable (BAT)
    BAT effluent limitations guidelines apply to direct dischargers of
toxic and nonconventional pollutants. In general, BAT effluent
limitations guidelines represent the best economically achievable
performance of facilities in the industrial subcategory or category.
The factors considered in assessing BAT include the cost of achieving
BAT effluent reductions, the age of equipment and facilities involved,
the process employed, potential process changes, and non-water quality
environmental impacts including energy requirements, and such other
factors as the Administrator deems appropriate. The Agency has
considerable discretion in assigning the weight to be accorded these
factors. An additional statutory factor considered in setting BAT is
economic achievability. Generally, EPA determines economic
achievability on the basis of total costs to the industry and the
effect of compliance with BAT limitations on overall industry and
subcategory financial conditions. Where existing performance is
uniformly inadequate, BAT may reflect a higher level of performance
than is currently being achieved based on technology transferred from a
different subcategory or category. BAT may be based upon process
changes or internal controls, even when these technologies are not
common industry practice.
2. New Source Performance Standards (NSPS)
    NSPS reflect effluent reductions that are achievable based on the
best available demonstrated control technology. Owners of new
facilities have the opportunity to install the best and most efficient
production processes and wastewater treatment technologies.

As a result, NSPS should represent the most stringent controls
attainable through the application of the best available demonstrated
control technology for all pollutants (that is, conventional,
nonconventional, and priority pollutants). In establishing NSPS, EPA is
directed to take into consideration the cost of achieving the effluent
reduction and any non-water quality environmental impacts and energy
requirements.
3. Pretreatment Standards for Existing Sources (PSES)
    Pretreatment standards apply to discharges of pollutants to POTWs
rather than discharges to waters of the United States. Pretreatment
Standards for Existing Sources are designed to prevent the discharge of
pollutants that pass through, interfere with, or are otherwise
incompatible with the operation of POTWs, including sludge disposal
methods of POTWs. Categorical pretreatment standards for existing
sources are technology-based and are analogous to BAT effluent
limitations guidelines.
    The General Pretreatment Regulations, which set forth the framework
for the implementation of categorical pretreatment standards, are found
at 40 CFR part 403.
4. Pretreatment Standards for New Sources (PSNS)
    Like PSES, PSNS are designed to prevent the discharges of
pollutants that pass through, interfere with, or are otherwise
incompatible with the operation of POTWs. New indirect discharges have
the opportunity to incorporate into their facilities the best available
demonstrated technologies. The Agency typically considers the same
factors in promulgating PSNS as it considers in promulgating NSPS.
5. BMPs
    Section 304(e) of the CWA authorizes the Administrator to publish
regulations, in addition to effluent limitations guidelines and
standards for certain toxic or hazardous pollutants, ``to control plant
site runoff, spillage or leaks, sludge or waste disposal, and drainage
from raw material storage which the Administrator determines are
associated with or ancillary to the industrial manufacturing or
treatment process . . . and may contribute significant amounts of such
pollutants to navigable waters.'' In addition, section 304(g), read in
concert with section 501(a), authorizes EPA to prescribe as wide a
range of pretreatment requirements as the Administrator deems
appropriate in order to control and prevent the discharge into
navigable waters either directly or through POTWs any pollutant which
interferes with, passes through, or otherwise is incompatible with such
treatment works. (see also Citizens Coal Council v. U.S. EPA, 447 F3d
879, 895-96 (6th Cir. 2006) (upholding EPA's use of non-numeric
effluent limitations and standards); Waterkeeper Alliance, Inc. v. U.S.
EPA, 399 F.3d 486, 496-97, 502 (2d Cir. 2005) (EPA use of non-numerical
effluent limitations in the form of BMPs are effluent limitations under
the CWA); and Natural Res. Def. Council, Inc. v. EPA, 673 F.2d 400, 403
(D.C. Cir. 1982) (``section 502(11) [of the CWA] defines `effluent
limitation' as `any restriction' on the amounts of pollutants
discharged, not just a numerical restriction.'')

C. The National Pretreatment Program, 40 CFR Part 403

    The General Pretreatment Regulations of 40 CFR part 403 establish
responsibilities among federal, state, local government, industry, and
the public to implement pretreatment standards to control pollutants
that pass through or interfere with the POTW treatment processes or
that can contaminate sewage sludge. The regulations, which have been
revised numerous times since originally published in 1978, consist of
20 sections and seven appendices. The General Pretreatment Regulations
use two terms describing oversight responsibilities under those
regulations. One is the term Control Authority. The ``Control
Authority'' refers to the POTW if the POTW has an approved Pretreatment
Program, or the Approval Authority if the program has not been
approved. The term Approval Authority describes the party with
responsibility to administer the National Pretreatment Program, which
is either a state with an approved state Pretreatment Program or, in a
state without an approved Pretreatment Program, the EPA region for that
state (40 CFR 403.3(f)). An approved Pretreatment Program is comprised
of legal authorities, procedures, funding, local limits, enforcement
response plan, and the list of significant industrial users (SIUs),
together which the Control Authority uses to implement the General
Pretreatment Regulations. The General Pretreatment Regulations apply to
all nondomestic sources that introduce pollutants into a POTW. These
sources of indirect discharges are more commonly referred to as
Industrial Users (IUs). All IUs are subject to general pretreatment
standards (40 CFR part 403), including a prohibition on discharges
causing ``pass through'' or ``interference'' (i.e., cause the POTW to
violate its permits limits, or interfere with the operation of the POTW
or the beneficial use of its sewage sludge). All POTWs with approved
Pretreatment Programs must develop local limits to implement the
general pretreatment standards. All other POTWs must develop such local
limits where they have experienced ``pass through'' or ``interference''
and such a violation is likely to recur. There are approximately 1,500
POTWs with approved Pretreatment Programs and 13,500 small POTWs that
are not required to develop and implement Pretreatment Programs.

D. State and Local Requirements

    Currently, 12 states (Connecticut, Louisiana, Maine, Massachusetts,
Michigan, New Hampshire, New Jersey, New York, Oregon, Rhode Island,
Vermont, and Washington) have implemented mandatory programs to reduce
dental mercury discharges.\3\ Additionally, at least 19 localities
similarly have mandatory dental reduction pretreatment programs. These
mandatory programs require the use of amalgam separators and BMPs.
Removal efficiency requirements for separators in mandatory program
jurisdictions vary from 95% to 99%. A full list of jurisdictions with
mandatory separator requirements can be found in the TEDD for this
proposed rulemaking.
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    \3\ New Mexico has a similar program that is scheduled to go
into effect in 2015.
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    Later in this document, EPA estimates costs and economic impacts
for this proposed rule. In order to do so, EPA needed to estimate
baseline compliance, or those dental offices that already have amalgam
separators installed, and, therefore, would incur lower costs and
impacts from the proposed rule. In order to estimate baseline
compliance, EPA distributed the number of dental offices shown in Table
IX-1 of Section IX by state,\4\ based on the 2007 Economic Census.
Because EPA has no data to indicate otherwise, EPA assumes 100%
compliance in the 12 states that require amalgam separators. For states
without mandatory programs, EPA assumed that 20% of dentists have
voluntarily installed amalgam separators. As a result, EPA estimates
approximately 40% of dental offices, nationally, have amalgam
separators installed (DCN DA00146). EPA, however, welcomes data and
comment on this assumption.
---------------------------------------------------------------------------

    \4\ Puerto Rico, the Virgin Islands, Pacific Islands and Tribal
Nations are not included in this analysis.

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

E. 2008 Memorandum of Understanding on Reducing Mercury Discharges

    In December 2008, EPA signed a Memorandum of Understanding (MOU)
with the ADA and the NACWA to establish and monitor the effectiveness
of a Voluntary Dental Amalgam Discharge Reduction Program. The purpose
of the MOU is to encourage dental offices to voluntarily install and
properly maintain amalgam separators, and recycle the collected amalgam
waste. Although EPA has not conducted a formal evaluation of the
effectiveness of the MOU, EPA is proposing National Pretreatment
Standards to accomplish the goals of the MOU in a more predictable
timeframe than a voluntary approach.

F. ADA BMPs and Support for a National Rulemaking

    ADA encourages dentists to handle mercury and mercury amalgam in a
manner that is consistent with ADA's ``Best Management Practices for
Amalgam Waste.'' ADA's BMPs are designed to reduce the amount of
mercury entering the environment. Practices encouraged by these BMPs
include reducing the volume of bulk elemental mercury in dentists'
offices, encouraging dentists to recycle amalgam to the greatest extent
possible, preventing mercury from being disposed of in medical waste
bags, and preventing amalgam from entering the wastewater stream. In
2007, ADA added the use of amalgam separators to their BMPs. See DCN
DA00165.
    In late 2010, ADA's Board of Directors adopted nine principles upon
which ADA supported National Pretreatment Standards for dental
facilities. See DCN DA00137.

IX. Description of the Dental Industry

    The industry category that would be affected by this proposed rule
is Offices of Dentists (NAICS 621210), which comprises establishments
of health practitioners primarily engaged in the independent practice
of general or specialized dentistry, or dental surgery. These
practitioners operate individual or group practices in their own
offices or in the offices of others, such as hospitals or health
maintenance organization medical centers. They can provide either
comprehensive preventive, cosmetic, or emergency care, or specialize in
a single field of dentistry.
    According to the 2007 Economic Census, there were 127,057 U.S.
dental offices owned or operated by 121,048 dental firms.\5\ Only 2% of
all dental firms were multi-unit with the vast majority being single-
unit. The growth of the number of dental offices has remained steady
over the past decade with an average increase of 1% per year.
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    \5\ A firm is a business organization, such as a sole
proprietorship, partnership, or corporation.
---------------------------------------------------------------------------

    The industry includes mostly small businesses with an estimated
99.8% of all offices falling below the Small Business Administration
(SBA) size standard ($7 million in annual revenue). Average revenues
for offices were estimated at $739,280 per year with an average of 6.50
employees per establishment.
    According to ADA data, approximately 80% of the dental industry
engages in general dentistry. Approximately 20% are specialty dentists
such as periodontics, orthodontics, radiology, maxillofacial surgery,
endodontists, or prosthodontics (DCN DA00123).
    One way to categorize dental offices is based on the number of
chairs in each facility. The 2007 Economic Census does not provide
information on the distribution of dental offices by the number of
chairs in each office. However, two studies, the ADA National Study and
a Colorado Study, demonstrate distribution of dentist offices by number
of chairs (DCN DA00141 and DCN DA00149). EPA used these two sources of
data to correlate the number of chairs per office to the revenue range
of dental offices. EPA averaged the correlation of these two studies.
The results are reported in table IX-1:

                            Table IX-1--Number of Dental Offices by Number of Chairs
----------------------------------------------------------------------------------------------------------------
                                                                          Number of offices by chair size
                                                                 -----------------------------------------------
                        Number of chairs                                             Colorado
                                                                    ADA survey        survey          Average
----------------------------------------------------------------------------------------------------------------
1-2 chairs......................................................          13,694          10,700          12,197
3 chairs........................................................          47,698          27,821          25,835
4 chairs........................................................                          32,102          27,976
5 chairs........................................................          29,388          15,694          15,194
6 chairs........................................................                           9,399          12,047
7+ chairs.......................................................          19,079          14,143          16,611
                                                                 -----------------------------------------------
    Total.......................................................         109,859         109,859         109,859
----------------------------------------------------------------------------------------------------------------

    Dentistry may also be performed at larger institutional dental
service facilities (e.g., clinics or dental schools). These facilities
are not included in the 2007 Economic Census data. EPA estimates 130
dental institutional facilities exist nationwide. EPA recognizes that
large facilities also may exist at installations operated by the
Federal Government, specifically the Department of Defense. While EPA
intends such facilities would be subject to today's proposed rule, EPA
does not have information to estimate the number of such facilities.
    EPA currently lacks a central database on reported discharges from
dental offices/clinics. Often, EPA looks to information in the Toxic
Release Inventory (TRI) and Discharge Monitoring Report (DMR) databases
to gather information on industrial discharges. However, no dental
offices/clinics (NAICS Code 621210) are required to report releases to
TRI. EPA identified only five dental offices that have National
Pollutant Discharge Elimination System (NPDES) permit information. All
dental offices were classified as minor dischargers. EPA has not found
any DMR data indicating that any significant number of dental offices
discharge directly to waters of the U.S. Therefore, EPA is not
proposing effluent limits for direct dischargers.\6\
---------------------------------------------------------------------------

    \6\ EPA recognizes that some dental facilities may discharge to
a septic system. This proposed rule does not apply to such
discharges.

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X. Summary of Data Collection

    In developing this proposed rule, EPA primarily used data
previously collected for its Health Services Detailed Study including
information submitted in public comments on the study. EPA also
collected information and data through outreach to a number of
stakeholders. The following describes EPA's outreach and additional
data sources for this proposed rule.

A. Health Services Industry Detailed Study on Dental Amalgam

    In 2008, EPA published its Health Services Industry Detailed Study
on Dental Amalgam. In the study, EPA compiled information on mercury
discharges from dental offices, BMPs, and amalgam separators. For
amalgam separators, EPA examined the frequency with which they were
used; their effectiveness in reducing discharges to POTWs; and the
capital and annual costs associated with their installation and
operation. EPA also conducted a POTW pass-through analysis on mercury
for the industry. This proposed rule relies heavily on data collected
for the study (including information submitted in public comments on
the study).

B. Environmental Council of the States (ECOS)

    EPA participated in several meetings with the Quicksilver Caucus
(QSC) of ECOS. From QSC, EPA collected information on implementing
mandatory amalgam separator programs at the state level, mandatory
program language, and information on compliance reporting and
monitoring. QSC also provided EPA with information on efficiency
standards for amalgam separators. See DCN DA00158.

C. Environmental Organizations

    EPA met with a coalition of environmental organizations, led by the
Environmental Law and Policy Center and the Natural Resources Defense
Council. Meetings between EPA and the coalition of environmental
organizations focused on identifying impacts of discharges of dental
amalgam to the environment. In Spring 2011, the coalition submitted a
letter listing its suggested BMPs for this proposed rule. See DCN
DA00136.

D. ADA

    EPA met with the ADA in 2010 and 2011. ADA submitted data to EPA on
its principles for addressing mercury discharges from dentists, the
proportions of specialties in the industry, the geographic distribution
of dentists, financial characteristics of the industry, and operating
characteristics of the industry. See DCN DA00137.

E. NACWA

    EPA met with NACWA in 2010 and 2011 to discuss the impact of
pretreatment standards on POTWs. NACWA provided EPA information on its
members' experiences with handling mercury pollution from dental
facilities, implementing pretreatment programs for dental facilities,
and its experiences implementing pretreatment standards for industries
with similar characteristics to the dental sector. NACWA also provided
EPA with information on the burden to permitting authorities that would
be associated with implementing a dental amalgam pretreatment standard
under the existing requirements in 40 CFR part 403. See DCN DA00144.

F. Amalgam Separator Manufacturers

    EPA met with, or participated in calls with, representatives of
multiple amalgam separator manufacturers. The purpose of the meetings
was to understand how amalgam separators work, limitations of the
technology, manufacturers' distribution methods, installation
requirements, capital and operation and maintenance costs, operation
and maintenance requirements, effectiveness, equipment lifetime,
amalgam disposal or recycling practices, manufacturing capacity, and
installation trends.

G. Air Force Study

    In anticipation of this proposed rule, the United States Air
Force's Dental Evaluation and Consultation Service compiled a synopsis
of commonly used amalgam separator systems. The synopsis describes
whether or not the separator is International Organization for
Standardization (ISO) 11143 certified, the installation requirements,
the design capacity, maintenance requirements for each model, the
availability of recycling services by the manufacturer, size, price,
and warranty details. EPA incorporated these data into the technology
cost analysis. The synopsis can be found in the TEDD for this proposed
rule.

XI. Wastewater Characteristics, Dental Office Configurations, and
Technology Options

A. Wastewater Sources and Wastewater Characteristics

    Dental amalgam consists of approximately 49% mercury by weight.
Mercury is the only metal that is in its liquid phase at room
temperature, and it bonds well with powdered alloy. This contributes to
its durability in dental amalgam. The other half of dental amalgam is
usually composed of 35% silver, 9% tin, 6% copper, 1% zinc and small
amounts of indium and palladium (DCN DA00131). Sources of mercury
discharges generally occur in the course of two categories of
activities. The first category of discharges may occur in the course of
treating a patient, such as during the placement or removal of a
filling. When filling a cavity, dentists overfill the tooth cavity so
that the filling can be carved to the proper shape. The excess amalgam
is typically rinsed into a chair-side drain, or suctioned out of the
patient's mouth. In addition to filling new cavities, dentists also
remove old cavity restorations that are worn or damaged. Removed
restorations also may be rinsed into the chair-side drain or suctioned
out of the patient's mouth. The second category of mercury discharges
occur in the course of activities not directly involved with the
placement or removal of dental amalgam. Preparation of dental amalgam,
disposing of excess amalgam, and flushing vacuum lines with corrosive
chemicals present opportunities for mercury from dental amalgam to be
discharged.

B. Dental Office Configurations

    The typical plumbing configuration in a dental office consists of a
chair-side trap for each chair, and a central vacuum pump with a vacuum
pump filter. Chair-side traps and vacuum pump filters remove
approximately 78% of dental amalgam particles from the wastewater
stream (DCN DA00163). Offices with multiple chairs typically share the
vacuum lines between chairs. Accordingly, this limits the locations for
installation of control and treatment technologies. Controls may be
installed: At or near each individual chair; within the vacuum system
piping; at a central location upstream of the vacuum pump; or at the
exit of the air/water separator portion of the vacuum system. Physical
office and building configurations may pose additional considerations,
such as space limitations, electrical power accessibility, and existing
sewer connections. In the case of very large offices, clinics, and
medical buildings, it may be possible to combine waste flows between
offices to share or reduce costs.

C. Control and Treatment Technologies and Best Management Practices

    As described previously, one source of the discharge of mercury
from dental amalgam occurs when dental amalgam enters the chair-side
drain, or is suctioned from the patient's mouth. The wastewater then
travels through the dental facility's vacuum system. EPA

identified two major technologies that intercept dental amalgam at this
point, before it is discharged from the dental office and flows to the
POTW: Separators and ion exchange. EPA also identified several BMPs
which, when employed along with the use of the technologies discussed
below, further reduce the discharge of dental amalgam from activities
not directly related to the placement or removal of dental amalgam.
1. Amalgam Separators
    An amalgam separator is a device designed to remove solids from
dental office wastewater. The amalgam separator is placed at some point
in the vacuum line, before the vacuum line intersects with plumbing in
other parts of the building, and separates solids from wastewater. Most
separator designs rely on the force of the dental facility's vacuum to
draw wastewater into the separator. However, the separation of solids
from the wastewater and the exit of the wastewater from the separator
will vary by design of the separator.
    Practically all amalgam separators on the market today use
sedimentation processes. The high specific gravity of amalgam allows
effective separation of amalgam from suspension in wastewater. Baffles
or tanks can reduce the speed of the wastewater flow, allowing more
amalgam particles to settle out. After the solids settle, the
wastewater is either pumped out, decanted during servicing, or is
pulled through the separator. Sedimentation-based separators are often
used over other separation technologies for their operational
simplicity.
    Some amalgam separators may combine filtration with separation.
Different types of filtration units can be employed to remove
additional amalgam particles. The amalgam separator may also be
designed to operate horizontally where wastewater is drawn into one
side of the separator, filtered, and then exits the opposite side of
the separator. This type of separator is designed to be completely
replaced once it reaches its design solids holding capacity. In
addition to combined separation and filtration units, EPA is aware of
at least one type of separator that utilizes centrifugation. A
centrifuge-based separator spins the water so that the heavier amalgam
particles are forced to the sides of the separator.
    A few amalgam separators combine sedimentation (with or without
filtration) with ion exchange in the same unit. This type of separator
additionally includes a chelating agent or proprietary resin. This type
of separator often requires special cleaning or additives to maintain
efficiency.
    The typical amalgam separator will operate in one of two ways. A
two-chambered separator is a design consisting of a base permanently
plumbed into the vacuum line, and a replaceable filtration cartridge.
The removable cartridge usually attaches to the bottom of the permanent
base. As wastewater enters the separator from the top of the unit,
gravity separates the wastewater from the air pulling it through the
vacuum. Air from the vacuum continues through the system by exiting a
bypass at or near the top of the base chamber. Wastewater then falls
through the base of the separator and enters the filtration cartridge.
As additional wastewater enters the separator, the filtration cartridge
will fill to capacity, and wastewater will begin to collect at the
bottom of the base chamber. Gravity forces wastewater in the separator
through a filtration device and out of the separator through a
decanting tube on the side of the separator. The wastewater, less the
solids retained by the separator, then continues through the vacuum
system and is eventually discharged from the dental office and to the
sanitary sewer and the POTW. The second common separator design
consists of a single chamber that requires wastewater to travel through
a filtration medium before it is drawn out of the separator. These
separators may be oriented vertically so that wastewater enters the top
of the unit, remains in the separator for some time, and allows solids
to settle. For either design, when the filtration cartridge or the
separator itself reaches the designed solids retention capacity, it
must be replaced. Manufacturers can include replacement schedules and
capacity levels for amalgam separators.
    The vast majority of amalgam separators on the market today have
been evaluated for their ability to meet the International Organization
for Standardization Standard for Dental Amalgam Separators (http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=42288). This voluntary standard setting
organization established a standard for measuring amalgam separator
efficiency by evaluating the retention of amalgam mercury using
specified test procedures in a laboratory setting. It also includes
requirements for instructions for use and operation and maintenance. In
order to obtain the ISO certification, a separator must achieve 95%
removal or greater of total mercury. Based on EPA's evaluation of a
range of amalgam separators as described above that meet the ISO
standard and that are currently on the market, certified separators
obtain a median of 99.0% total mercury removal efficiency (see Section
7 of the TEDD). When existing chair side traps and vacuum pump filters
are used upstream of the amalgam separators, the combined treatment
system can achieve total mercury removal rates exceeding 99% (DCN
DA00008).
    EPA is proposing to include certain operation, maintenance, and
inspection activities that have the greatest impact on the ability of
an amalgam separator to achieve its performance as certified. Once the
separator reaches solids retention capacity, vacuum suction will begin
to diminish or, more commonly, the separator will enter bypass mode.
Wastewater running through a separator in bypass mode flows through the
separator without being filtered, rendering the separator ineffective.
Because many separators can enter bypass mode without any noticeable
effect on vacuum suction, it would be important that the unit be
checked periodically, and if necessary, serviced.\7\
---------------------------------------------------------------------------

    \7\ There may be separators on the market that do not notify
users when they are in bypass mode or otherwise require servicing.
These separators would not meet ISO certification standards.
---------------------------------------------------------------------------

    Solids collected by the amalgam separator may be a combination of
dental amalgam, biological material from patients, and any other solid
material sent down the vacuum line. Amalgam separator manufacturer
instructions should be followed for servicing amalgam separators and
for handling separator waste. Some amalgam separator manufacturers also
offer waste management services. Examples of services provided include
ensuring that waste collected by the separator is handled according to
state and local requirements, and providing necessary compliance
documentation for the facility's recordkeeping requirements. In the
event that these services are not employed, the facility should dispose
of amalgam waste in accordance with state and local requirements.
    Most amalgam separators are compatible with both wet and dry vacuum
systems, and with both large and small dental offices.\8\ As explained
in Section VIII, currently at least 12 states and 19 localities have
implemented mandatory programs to reduce dental mercury discharges. All
of these programs require the use of

amalgam separators. Further, many dental offices in states or
localities without mandatory programs have voluntarily installed dental
amalgam separators, and the ADA recommends their use as part of its
``Best Management Practices for Amalgam Waste'' (2007). As described in
Section VIII, EPA estimates that 40% of dental offices currently employ
amalgam separators.
---------------------------------------------------------------------------

    \8\ This does not mean all types of separators are compatible at
a given dental office. For example, an amalgam separator that relies
on filtration technology may not be compatible with a dry vacuum
system in place.
---------------------------------------------------------------------------

2. Polishing To Remove Dissolved Mercury From Wastewater
    Mercury in dental amalgam is present in both the suspended and
dissolved form. The vast majority (>99.6%) is suspended (DCN DA00018).
An additional process sometimes referred to as ``polishing'' uses ion
exchange to remove dissolved mercury. In contrast to amalgam separators
that contain an ion exchange component in the same unit, as discussed
in the previous section, ``polishing'' ion exchange refers to a
separate wastewater treatment system added after the amalgam separator
for the purpose of removing dissolved mercury.
    Dissolved mercury has a tendency to bind with other chemicals,
resulting in a charged complex. Ion exchange is the process that
separates these charged amalgam particles from the wastewater. Ion
exchange does not rely on physical settling of particles, and can
remove very small amalgam and ionic mercury particles. This technology
may be preferable over sedimentation (with or without filtration) alone
because dissolved mercury is removed by this process. For example, ion
exchange might be useful in municipalities that have concentration
limits on mercury (McManus, 2003). EPA is not aware of any state
regulations that require ion exchange.
    For ion exchange to be most effective, the incoming wastewater to
be treated must first have the solids removed. Then the wastewater
needs to be oxidized in order for the resin or mercury capturing
material to capture the dissolved mercury. Therefore, ion exchange will
not be effective without first being preceded by a solids collector. As
a result, EPA concludes this sequential polishing approach, in which
amalgam separators and ion exchange are separate units, is more
effective than the single units described above that combine
sedimentation and ion exchange. Dental offices needing to employ
polishing would likely need to add a separate ion exchange unit
following the amalgam separator to remove additional mercury from the
waste stream.
    As explained above, ISO certification testing is based on an
evaluation of the removal of total mercury in a laboratory setting and
does not differentiate removal for the suspended and dissolved
forms.\9\ In order to better understand the reductions in dissolved
mercury that can be achieved with the addition of ion exchange as
polishing, EPA reviewed available data on the performance from actual
installations of ion exchange units in addition to amalgam separators
in dental offices. EPA found the use of polishing is limited to just a
handful of dental offices. EPA identified only one study of polishing
systems, and has not identified any further data pertaining to the
performance of polishing. This one study evaluated the additional
efficacy associated with polishing at two dental facilities in response
to sanitation district concerns over mercury discharges. In both cases,
the polishing systems were installed after the amalgam separators but
prior to discharge into the treatment plant's collection system. While
a reduction was observed in the final effluent mercury after the
polishing system was installed, preliminary EPA Region 8 audits showed
the total additional mercury reductions were typically on the order of
0.5% (DCN DA00164). This is not surprising since, as indicated above,
dissolved mercury contributes such a small portion to the total amount
of mercury in dental amalgam. It is unclear whether any solid mercury
was converted to dissolved mercury, and additional monitoring data are
not yet available.
---------------------------------------------------------------------------

    \9\ In some cases, the ISO testing results include ranges of
dissolved mercury in the effluent.
---------------------------------------------------------------------------

    The capital costs of the polishing system, as a stand-alone system,
are approximately four times that of the amalgam separator; the costs
for chemical use, regenerating the resin, filter replacement, and other
operational costs were not reported. Further, EPA is uncertain whether
typical dental buildings have adequate space to install the holding
tanks needed to oxidize the waste before treatment, as well as space
for the polishing equipment itself.

D. Best Management Practices

    EPA considered what BMPs reflect the best available technology
economically achievable or best available demonstrated control
technology--the standards applicable to existing and new sources
subject to categorical pretreatment standards. After this review, EPA
proposes to include certain operation, maintenance, and inspection
practices as part of the technology basis for this proposed rule. These
practices have the greatest impact on the ability of an amalgam
separator to achieve its performance as certified.
    EPA also proposes to require two BMPs to control mercury discharges
that would not be captured by an amalgam separator. Bleach and other
corrosive cleaners can solubilize bound mercury. If corrosive cleaners
are used to clean vacuum lines that lead to an amalgam separator, the
line cleaners may solubilize any mercury that the separator has
captured, leading to increased mercury discharges. Therefore, EPA
proposes to require line cleaners that do not contain bleach, and are
of neutral pH.
    Flushing scrap amalgam (contact and non-contact), including dental
amalgam from chair-side traps, screens, vacuum pump filters, dental
tools, or collection devices into drains that do not have a solids
collecting device presents additional opportunities for mercury to be
discharged from the dental office. Therefore, EPA proposes to include a
BMP that prohibits flushing scrap dental amalgam into any drain that is
not connected to an amalgam separator.

XII. Scope/Applicability

    As mentioned in the previous section, EPA has not identified dental
offices/clinics discharging directly to waters of the U.S. Because EPA
has very limited information on any direct discharge of dental amalgam,
EPA is not proposing effluent limitations guidelines and new source
performance standards for direct dischargers at this time.
    As such, EPA is proposing to apply this rule to wastewater
discharges to POTWs from offices where the practice of dentistry is
performed, including institutions, permanent or temporary offices,
clinics, mobile units, home offices, and facilities, and including
dental facilities owned and operated by Federal, state, or local
governments. EPA is not proposing to include wastewater discharges from
dental facilities where the practice of dentistry consists exclusively
of one or more of the following dental specialties: oral pathology,
oral and maxillofacial radiology, oral and maxillofacial surgery,
orthodontics, periodontics, or prosthodontics. As described in the
TEDD, these specialty practices do not engage in the practice of
restorations or removals, and are not expected to have any discharges
of dental amalgam.

XIII. Subcategorization

    In developing effluent limitations guidelines and pretreatment
standards, EPA may divide an industry category into groupings called
''subcategories'' to

provide a method for addressing variations among products, processes,
and other factors, which result in distinctly different effluent
characteristics. See Texas Oil & Gas Ass'n. v. U.S. EPA, 161 F.3d 923,
939-40 (5th Cir. 1998). Regulation of a category by subcategories
provides that each subcategory has a uniform set of effluent
limitations or pretreatment standards that take into account
technological achievability, economic impacts, and non-water quality
environmental impacts unique to that subcategory. In some cases,
effluent limitations or pretreatment standards within a subcategory may
be different based on consideration of these same factors, which are
identified in CWA section 304(b)(2)(B). The CWA requires EPA, in
developing effluent guidelines and pretreatment standards, to consider
a number of different factors, which are also relevant for
subcategorization. The CWA also authorizes EPA to take into account
other factors that the Administrator deems appropriate.
    In developing the proposed rule, EPA considered whether
subcategorizing the dental industry was warranted. EPA evaluated a
number of factors and potential subcategorization approaches, including
the size of dental office, specialty practices, and unusual
configurations that may be found at very large offices such as clinics
and universities. EPA proposes that establishing formal subcategories
is not appropriate for the Dental Amalgam category for three reasons.
First, the proposed rule is structured to set standards only for those
facilities that discharge dental amalgam. Second, the requirements do
not include a size threshold because the technology is readily scaled
to the size of the dental office. Finally, those states and localities
that already have regulatory programs for controlling discharges of
dental amalgam have been largely successful without subcategorization.

XIV. Proposed Regulation

A. PSES Options Selection

    Section XI discussed the technologies identified to control amalgam
discharges from dental offices. EPA identified two basic technologies,
amalgam separators and polishing. EPA determined separators plus
polishing is not ``available'' as that term is used in the CCWA.
    EPA identified one technology that is available and demonstrated--
amalgam separators. EPA further identified BMPs that would ensure the
effectiveness of the amalgam separator technology and would reduce
discharges of dental amalgam not captured by an amalgam separator.
Therefore, EPA developed a regulatory option based on proper operation
and maintenance of amalgam separators that achieve a 99.0% reduction of
total mercury from amalgam process wastewater with BMPs. Compliance
with the numeric pretreatment standard for new and existing sources
could be met by installation and proper operation and maintenance of an
amalgam separator certified to meet at least 99.0% reduction of total
mercury according to the 2008 ISO 11143 standard. Compliance with two
additional BMPs--not flushing scrap amalgam down the drain and cleaning
of chair side traps with non-bleach, non-chlorine cleaners--are
necessary to prevent mercury discharges that would bypass the
separator. EPA finds that the proposed technology basis is
``available'' as that term is used in the CWA because it is readily
available and feasible for all dental offices. ADA recommends its
dentists use the technology on which this rule is based (i.e., amalgam
separators and BMPs). Further, EPA estimates that 40% of dental offices
currently use amalgam separators on a voluntary basis or are in states
with state or local laws requiring the use of amalgam separators. For
those dental offices that have not yet installed an amalgam separator,
EPA estimates this is a low cost technology with an approximate average
annual cost of $700 \10\ per office. EPA's economic analysis analyzes
these costs in relation to the overall income of the regulated entities
and shows that this proposed rule is economically achievable (see
Section XVI). Finally, EPA also examined the non-water quality
environmental impacts of the proposed rule and found them to be
acceptable. See Section XX, ``Non Water Quality Environmental
Impacts.''
---------------------------------------------------------------------------

    \10\ This estimate is based on the average annualized cost for
dentists that do not currently have an amalgam separator. See DCN
DA00145.
---------------------------------------------------------------------------

    EPA is not proposing to establish pretreatment standards based on
technologies that remove dissolved mercury, or polishing. None of the
states with mandated requirements to reduce dental mercury discharges
requires polishing. EPA also lacks adequate performance data to truly
assess the efficacy of polishing or its availability of ion exchange
for nationwide use. EPA's current information suggests that polishing
only achieves incremental removals over the BAT selected technology of
less than one half percent of total mercury. While even very small
amounts of mercury have environmental effects, EPA lacks sufficient
data to conclude that there is a significant difference in the
performance between the two technologies. EPA estimates that the
capital costs of amalgam separators and polishing are at least four
times that of amalgam separators alone (see DCN DA00122). Finally, EPA
is uncertain whether existing dental offices have adequate space to
install polishing controls. These factors led EPA to find that
polishing is not ``available'' as that term is used in the CWA. As a
result, EPA did not select amalgam separators followed by polishing as
the technology basis for this proposed rule. EPA solicits data on the
costs, performance, affordability, and availability of polishing in
combination with amalgam separators.

B. Pollutants of Concern and Pass Through

    Of the dental amalgam constituents, mercury is of greatest concern
to human health because it is a persistent, bioaccumulative, toxic
chemical and can bioaccumulate three to ten times across each trophic
level of the food chain. Mercury from dental amalgam makes its way into
the environment when it is discharged from the dental facility to a
POTW, where it settles into sewage sludge, or is discharged to surface
waters. Once discharged, certain microorganisms change mercury into
methylmercury, a form of mercury that can be absorbed by fish,
shellfish and animals that eat fish.
    EPA finds that the technologies considered for control of amalgam
solids will be similarly effective on other metals contained in dental
amalgam because these metals are in a solids form, and the separation
technology is designed to remove solids. Therefore any controls
established for the reduction of mercury discharges will similarly
reduce the discharge of other metals contained in amalgam. As such, EPA
focused its consideration of regulated pollutants on mercury.

C. POTW Pass Through Analysis

    To establish pretreatment standards, EPA examines whether the
pollutants discharged by the industry ``pass through'' a POTW to waters
of the U.S. or interfere with the POTW operation or sludge disposal
practices. EPA's consideration of pass through for national technology
based categorical pretreatment standards differs from that described in
Section VIII for general pretreatment standards. For categorical
pretreatment standards, EPA's approach for pass through satisfies two
competing objectives set by Congress: (1) That standards for indirect
dischargers be

equivalent to standards for direct dischargers; and (2) that the
treatment capability and performance of the POTWs be recognized and
taken into account in regulating the discharge of pollutants from
indirect dischargers.
    Generally, in determining whether pollutants pass through a POTW
when considering the establishment of categorical pretreatment
standards, EPA compares the percentage of the pollutant removed by
typical POTWs achieving secondary treatment with the percentage of the
pollutant removed by facilities meeting BAT effluent limitations. A
pollutant is deemed to pass through a POTW when the average percentage
removed by a typical POTW is less than the percentage removed by direct
dischargers complying with BPT \11\/BAT effluent limitations. In this
manner, EPA can ensure that the combined treatment at indirect
discharging facilities and POTWs is at least equivalent to that
obtained through treatment by a direct discharger, while also
considering the treatment capability of the POTW.
---------------------------------------------------------------------------

    \11\ Best Practicable Control Technology Currently Available.
---------------------------------------------------------------------------

    In the case of this proposed rulemaking, where only pretreatment
standards are being developed, EPA compared the POTW removals with
removals achieved by indirect dischargers using the candidate
technology that otherwise satisfies the BAT factors. Historically,
EPA's primary source of POTW removal data is its 1982 ``Fate of
Priority Pollutants in Publicly Owned Treatment Works'' (also known as
the 50 POTW Study). The 50 POTW study presents data on the performance
of 50 POTWs achieving secondary treatment in removing toxic pollutants.
Results of this study demonstrate POTWs remove 90% of total mercury
found in wastewater. EPA has data from targeted studies performed by
NACWA and ADA that indicate a POTW can remove 95% of total mercury.
However, these studies reflect the performance of best performing
POTWs, as opposed to the 50 POTW Study which reflects nationwide POTWs.
Consequently, for this proposal, EPA maintains a POTW percent removal
rate of 90% for its nationwide pass-through analysis. In comparison,
indirect dischargers using this proposed technology will remove 99.0%
or more total mercury prior to discharge. Therefore, EPA concludes
mercury passes through \12\ and is today proposing requirements to
control its discharge.
---------------------------------------------------------------------------

    \12\ For all the metals contained in dental amalgam, EPA's
record demonstrates that these pollutants would similarly pass
through as defined above. See the Pollutant Reduction Estimates
section of the TEDD for POTW removal estimates for the other metals.
---------------------------------------------------------------------------

D. Requirements

    This proposed rule would establish a pretreatment standard that
would require removal of at least 99.0% of total mercury from amalgam
discharges and BMPs. One way affected dental offices would be able to
meet the standard would be to use, and properly operate and maintain, a
dental amalgam separator certified to achieve at least 99.0% reduction
of total mercury according to the 2008 ISO 11143 standard, to perform
certain BMPs, and to certify to this effect. Another way affected
dental offices would be able to meet the standard would be to certify
that they do not install or remove amalgam except in limited emergency
circumstances. Dentists that certify that they do not install or remove
amalgam will be exempt from any further requirements of the proposed
rule.
    While the proposed rule does not require the use of an amalgam
separator to meet the numeric standard, EPA expects that most, if not
all dentists that place or remove amalgam would use this widely
available technology to comply with the proposed numeric standard. EPA
expects dentists will choose to install and operate an amalgam
separator because of the nature of dental offices, the variability of
the flows and resulting waste streams, and the difficulty in obtaining
a sample that represents only dental amalgam discharges. Moreover,
amalgam separators are an easy to use, low cost technology. Dental
offices that elect to not use an amalgam separator must meet the
proposed numeric limit and would be subject to the oversight and
compliance requirements for indirect discharges subject to national
pretreatment requirements.
    In selecting an amalgam separator that meets the requirements of
today's proposed pretreatment standards, dentists would verify that the
amalgam separator is compliant with the 2008 ISO 11143 standard and
meets the design specifications of the proposed regulation for their
configuration. Once selected and installed, EPA expects dentists will
operate and maintain the separator following all manufacturer's
instructions and conduct inspections at least monthly to ensure all
features are functional.
    This proposal would subject all dentists (except those specialists
as described in Section XII) to categorical pretreatment requirements.
EPA recognizes that some dentists covered by this proposal do not apply
or remove dental amalgam except possibly in limited emergency
circumstances. However, EPA, in consultation with pretreatment
authorities, has been unable to identify a publically available source
of information that differentiates dental offices on the basis of
whether or not dental amalgam may reasonably be expected to be present.
As such, this proposed rule would apply to such dischargers and require
them to report baseline information, but it would also allow them to
certify (at any time) that they do not and will not install or remove
amalgam (not including infrequent emergency treatment as discussed
below). This would fulfill their obligations under this proposed rule.
If they subsequently elect to install or remove amalgam, they would
then need to comply with the proposed numeric standard (e.g., proper
operation and maintenance of an amalgam separator) and with the BMPs in
this proposed rule.\13\
---------------------------------------------------------------------------

    \13\ EPA recognizes that dentists, infrequently, may remove
amalgam in the course of emergency treatment. EPA does not intend
for discharges of dental amalgam, related to only these infrequent
emergency treatments, to preclude such dentists from certifying.
---------------------------------------------------------------------------

    EPA does not want to penalize existing dental offices or
institutional dental facilities that have already installed amalgam
separators either voluntarily or to comply with state or local
requirements. EPA recognizes that these offices may currently have
amalgam separators in place that are certified to a removal rate
slightly less than this proposed standard. For example, some states
require dental offices to employ amalgam separators that are certified
to remove 95% total mercury. EPA does not propose a rule that would
require existing separators that still have a remaining useful life to
be retrofitted with new separators, both because of the additional
costs incurred by dental facilities that moved ahead of EPA's proposed
requirements to install a treatment technology and because of the
additional solid waste that would be generated by disposal of the
existing separators. Therefore, EPA is proposing that, as long as they
continue to properly operate and maintain existing separators, comply
with BMPs, and comply with recordkeeping requirements, these facilities
would be considered in compliance with the numeric standard until ten
years from the effective date of the final rule. EPA selected ten years
because it appears to be a conservative estimate of the useful life of
the existing equipment. However, if prior to that time, the currently
installed separator needs to be replaced, these facilities would need
to install and

operate an amalgam separator that meets a removal efficiency of 99.0%.
    EPA requests comment on this proposed regulatory scheme. In
particular, EPA seeks comment on its approach for addressing offices
where no dental amalgam is placed or removed except in limited
emergency circumstances, and its approach for offices that have already
installed an amalgam separator.

E. PSNS Option Selection

    As previously noted, under section 307(c) of the CWA, new sources
of pollutants into POTWs must comply with standards which reflect the
greatest degree of effluent reduction achievable through application of
the best available demonstrated control technologies. Congress
envisioned that new treatment systems could meet tighter controls than
existing sources because of the opportunity to incorporate the most
efficient processes and treatment systems into the facility design. EPA
proposes PSNS that would control the same pollutants using the same
technologies proposed for control by PSES. The technologies used to
control pollutants at existing offices, amalgam separators and BMPs,
are fully applicable to new offices. New dental offices can incorporate
amalgam separators into the design and installation of their vacuum
system. Furthermore, EPA has not identified any technologies that are
demonstrated for new sources that are more effective than those
identified for existing sources. Finally, EPA determined that the
proposed PSNS present no barrier to entry. EPA has found that overall
impacts from the proposed standards on new sources would not be any
more severe than those on existing sources, since the costs faced by
new sources generally will be the same as or less than those faced by
existing sources. Therefore, EPA proposes to establish NSPS that are
the same as those proposed for PSES.
    EPA does not propose to establish more stringent requirements for
new sources based on technologies that remove dissolved mercury (i.e.,
polishing) for the same reasons stated above for existing standards.

XV. Technology Costs

    This section summarizes EPA's approach for estimating compliance
costs, while the TEDD provides detailed information on the methodology.
EPA's cost methodology assumes dental offices would use the required
BMPs in combination with 2008 ISO 11143 amalgam separators on the
market today to comply. See DCN DA00138. EPA categorized all of the
costs as either capital costs \14\ (one-time costs associated with
planning or installation of technologies), as operation and maintenance
(O&M) costs (costs that occur on a regular ongoing basis such as
inspection or cleaning of the unit or annual purchases of amalgam
cartridges), or as reporting costs. All final cost estimates are
expressed in terms of 2010 dollars.
---------------------------------------------------------------------------

    \14\ See Section XVI and the Economic Section of the Technical
Development Document for information on how EPA annualized costs.
---------------------------------------------------------------------------

    EPA estimated compliance costs associated with this proposal using
data collected through EPA's Health Services Industry Detailed Study
(August 2008) [EPA-821-R-08-014], a review of the literature, and
information supplied by vendors. EPA's cost estimates represent the
incremental costs for a dental office to comply with this proposed
rule. For costing purposes, EPA differentiated dental offices by those
that already use amalgam separators and those that do not.
    EPA recognizes that some fraction of dental offices subject to this
proposed rule may not place or remove amalgam and proposes to allow
them to submit a one-time baseline monitoring report. Such dental
offices would be exempt from this rule so long as they do not place or
remove amalgam. Should the status of the dental office change, the
certification would no longer be valid. For example, if a dental office
so certifies and is sold, the new owner must similarly so certify or
would need to comply with the rule. See Sec.  441.10. EPA estimates the
costs associated with this one-time only certification to be $22.
    In general, one approach that EPA takes to estimate compliance
costs is to use facility-specific data to determine what requirements
apply to a given facility and whether that facility would already meet
the proposed requirements. This approach requires facility specific
technical and financial data. In this case, EPA would need such data
for approximately 110,000 dental offices estimated to be subject to
this rule. Such data are not available. An alternative approach often
used by EPA is to develop a series of model facilities that exhibit the
typical characteristics of the affected facilities and calculate costs
for each model facility. EPA can then determine how many of the
affected facilities are represented nationally by each model facility
to represent the full universe of affected facilities.

A. Methodology for Developing Model Dental Office Costs

    EPA used the model approach to estimate costs for facilities that
place or remove amalgam for this proposal. The model facility approach
used in this effort involved calculating compliance costs for each of
the size classes of dental offices described in Section IX of this
preamble. In other words, EPA developed compliance costs for six models
based on the number of chairs in an office. The ranges for each model
are as follows: 1 to 2 chairs, 3 chairs, 4 chairs, 5 chairs, 6 chairs,
and 7+ chairs (average of 10 chairs). In addition to each of the size
class models, EPA developed a model facility to represent very large
offices such as clinics and universities. This is discussed separately
in Section XV. B., below.
    EPA developed two sets of costs for each model: one for facilities
that do not use an amalgam separator and one for facilities that do.
For those that do not use an amalgam separator, EPA estimated capital
costs and operation and maintenance costs. Capital costs include
purchase of the separator and installation. Recurring costs include
replacement of the cartridge, and operation and maintenance costs. A
summary of costs for dental offices that do not currently use amalgam
separators may be found in Tables XV-1 and XV-2.

    Table XV-1--Summary of One Time Model Facility Costs ($2010) for Dental Offices That Do Not Currently Use
                                               Amalgam Separators
----------------------------------------------------------------------------------------------------------------
                                                          Number of chairs in the model dental office
                Cost element                 -------------------------------------------------------------------
                                                   1 or 2      3, 4, or 5 \15\         6                7+
----------------------------------------------------------------------------------------------------------------
Separator Purchase..........................             $502             $599           $1,058           $1,531

Installation................................              250              250              250              250
----------------------------------------------------------------------------------------------------------------

    Table XV-2--Summary of One Time Model Facility Costs ($2010) for Dental Offices That Do Not Currently Use
                                               Amalgam Separators
----------------------------------------------------------------------------------------------------------------
                                                          Number of chairs in the model dental office
                Cost element                 -------------------------------------------------------------------
                                                   1 or 2      3, 4, or 5 \16\         6                7+
----------------------------------------------------------------------------------------------------------------
Replacement Parts...........................             $195             $219             $430             $647
O&M Including Recycling.....................              216              216              216              216
----------------------------------------------------------------------------------------------------------------

    For those  facilities that already have an amalgam separator, EPA
calculated costs for certain additional recurring operation and
maintenance associated with the amalgam separator compliance  option in
this proposal. Recurring costs include replacement of the cartridge and
operation and maintenance costs. A summary of these costs may be found
in Table XV-3. This is a conservative approach to costing, however,
because some of these facilities would presumably continue to operate
and maintain the separators that they have already chosen or been
required to install.
---------------------------------------------------------------------------

    \15\ EPA assumed the separator can be sized for 3, 4, or 5
chairs, but has kept these three model office sizes distinct because
the economic analysis evaluates different revenues for each of these
sized offices.
    \16\ EPA assumed the separator can be sized for 3, 4, or 5
chairs, but has kept these three model office sizes distinct because
the economic analysis evaluates different revenues for each of these
sized offices.

    Table XV-3--Summary of Annual Model Facility Costs ($2010) for Dental Offices That Currently Use Amalgam
                                                   Separators
----------------------------------------------------------------------------------------------------------------
                                                          Number of chairs in the model dental office
                Cost element                 -------------------------------------------------------------------
                                                   1 or 2      3, 4, or 5 \17\         6                7+
----------------------------------------------------------------------------------------------------------------
Replacement Parts...........................              $98             $110             $215             $324
O&M including recycling.....................              116              116              116              116
----------------------------------------------------------------------------------------------------------------

    In assessing  the long term costs of rule compliance for these
model facilities (those with and without existing separators), EPA
estimated that amalgam separators would have a service life of 10
years, at which time the amalgam separators would need to be replaced.
For the purposes of cost estimates for this proposal, EPA assumed that
all offices regardless of the original technology in-place would incur
the full cost of purchasing amalgam separators at the time of
reinstallation. However, because various modifications needed by the
office for initial amalgam separator installation would have already
been completed, EPA has projected that amalgam separators replaced
beyond year 10 would be installed at one-half of the cost of the
original installation. For example, EPA assumed plumbing modifications
for initial installation would cost $250 per office, but that replaced
equipment would cost $125 to install. EPA assumed that dental offices
would continue to incur recurring expenses such as O&M in the same way
as described for the initial installation.
---------------------------------------------------------------------------

    \17\ EPA assumed the separator can be sized for 3, 4, or 5
chairs, but has kept these three model office sizes distinct because
the economic analysis evaluates different revenues for each of these
sized offices.
---------------------------------------------------------------------------

    Finally, all dental offices subject to this proposed rule will also
have reporting requirements and BMP requirements. EPA also included
reporting costs for one-time preparation of a baseline report and
initial compliance report and recurring costs associated with
preparation of an annual certification statement. Section XI describes
the BMPs in this proposal. EPA projects that there will be no
incremental costs associated with these BMPs, because 1) costs for non-
oxidizing, pH neutral line cleaners are roughly equivalent to other
line cleaners; and 2) dentists will not incur additional costs by
changing the location for flushing scrap amalgam.

B. Methodology for Developing Costs for Institutional Facilities

    Institutional dental service facilities (e.g., clinics or dental
schools), have a larger number of chairs than the typical dental
office. For these institutional dental facilities, EPA developed a
costing methodology based on the methodology for offices described
above. For purposes of costs, EPA assumed the average institutional
facility has 15 chairs. In the methodology described previously, the
model practice with the largest number of chairs for which EPA
developed cost information is the 7+ chair model with an average of 10
chairs. Scaling the information on costs for the 10 chair model
facility to a 15 chair operation using a straight ratio yields costs at
these institutional facilities at 1.5 times the costs estimated for the
largest chair range shown in Table XV-1 and Table XV-2. These costs are
likely overstated as they do not reflect opportunities the largest
offices may have to share costs,\18\ and they do not assume any
economies of scale. EPA solicits comment and data regarding EPA's
analysis of clinics and institutional facilities.
---------------------------------------------------------------------------

    \18\ For example, multiple offices located in a single building
or complex may be able to share plumbing, vacuum systems, and may be
able to install a larger separator rather than each office having
its own separator.
---------------------------------------------------------------------------

XVI. Economic Impact Analysis

    This section summarizes EPA's assessment of the costs and impacts
of the proposed pretreatment standards on the regulated industry.

A. Social Cost Estimates

    As described earlier in Section XIV of this preamble, EPA proposes
PSES and PSNS based on a widely available technology, amalgam
separator, and employment of BMPs. Section XV provides a detailed
explanation of how EPA estimated compliance costs for model dental
offices. As described there, EPA developed compliance costs for six
models based on the number of chairs in an office. The ranges for each
model are as follows: 1 to 2 chairs, 3 chairs, 4 chairs, 5 chairs, 6
chairs, and 7+ chairs (average of 10 chairs). In addition to each of
the size class models, EPA developed a model facility to represent
institutional facilities such as clinics and universities.
    For each model facility, EPA estimated compliance costs for dental
offices that currently use a separator, those that do not have a
separator in place, and those that certify that they do not place or
remove amalgam. For those that do not currently use a separator, EPA
estimated costs as either capital costs (one-time costs associated with
planning or installation of technologies), as O&M costs (costs that
occur on a regular ongoing basis such as inspection or cleaning of the
unit, annual purchases of amalgam cartridges, and recycling), and as
reporting costs. For those that use a separator (approximately 40% of
dental offices as reported in Section VIII), EPA estimated O&M costs
and reporting costs only. As applicable, EPA annualized the capital
costs over a 20-year period at a discount rate of 3%\19\  and summed
these costs with the O&M and reporting costs to determine an annual
compliance cost estimate for each model facility. In order to develop a
national estimate of social costs \20\ based on these model facilities,
EPA estimated the number of dental offices represented by each model
facility. As explained in Section IX, EPA estimated the number of
dental offices based on data from the 2007 Economic Census \21\
describing the number of establishments in the Offices of Dentists
NAICS (621210), and their annual revenue. Because reported
establishments were described by their annual revenue and not number of
chairs (the basis of model compliance costs), EPA used data from two
surveys, a Colorado survey and an ADA survey, to correlate the
estimated number of chairs per office to the revenue range of dental
offices. Because EPA used two different data sources, results are
presented as a range. Details of the relationship between chairs and
revenue can be found in the TEDD.
---------------------------------------------------------------------------

    \19\ See the TEDD for the reported analyses using a 7% discount
rate.
    \20\ Costs of the rule, from the standpoint of cost to society,
include compliance costs and administrative costs to control
authorities. Social costs would also incorporate any adjustment
based on a quantity demand response to a change in price driven by a
price change due to cost pass-through to consumers. For this
analysis, EPA is not able to demonstrate an observable change in
price for dental services, therefore no observable change in amount
of visits (quantity demanded). Therefore EPA makes no adjustment to
social costs based on a change in quantity.
    \21\ EPA adjusted the 2007 Economic Census revenue values to
reflect 2010 dollars.
---------------------------------------------------------------------------

    To estimate nationwide social costs, EPA multiplied the estimated
total annualized costs of rule compliance for each model facility by
the estimated number of dental offices represented by that model (i.e.
with the indicated number of chairs and with/without existing amalgam
separators). EPA also accounted for some dental offices that may not
place or remove amalgam and assigned them costs only for a one-time
baseline monitoring report. EPA then summed the values for each chair
range over the number of chair ranges to yield the total estimated
compliance cost.
    Similarly, EPA calculated costs for institutional facilities by
multiplying the compliance cost for its model institutional facility by
the number of estimated institutional facilities indicated in Section
IX. Lastly, EPA estimated costs for control authorities for
administering the Dental Amalgam Rule.\22\ Details of this cost
analysis can be found in the TEDD. See Table XVI-1 for EPA's estimate
of nationwide annualized costs for each chair range represented by
EPA's model facilities as well as EPA's estimate of total nationwide
annualized costs for this proposed rule.
---------------------------------------------------------------------------

    \22\ As a point of clarification, for this proposal, social
costs equal the sum of compliance costs and administrative costs.

     Table XVI-1--Total Annualized Social Costs by Number of Chairs
                       [Millions of 2010 dollars]
------------------------------------------------------------------------
                                    Total annualized costs by chair size
                                                     \1\
         Number of chairs          -------------------------------------
                                     Colorado survey       ADA Survey
------------------------------------------------------------------------
1-2 chairs........................               $3.4               $4.4
3 chairs..........................                9.5               16.3
4 chairs..........................               11.0
5 chairs..........................                5.4               14.8
6 chairs..........................                4.7
7+ chairs.........................                9.5               12.8
Large Dental Facilities...........                0.1                0.1

Cost to Control Authorities.......                0.9                0.9
                                   -------------------------------------
    Total Annualized Social Costs.               44.5               49.4
------------------------------------------------------------------------
\1\ EPA assumed that initial capital outlays and initial incurrence of
  ongoing compliance expenses would occur in the third year following
  rule promulgation. EPA assumed that the amalgam separator technology
  would have a service life of 10 years, and used a 20-year analysis
  period to allow for one-time replacement of capital equipment 10 years
  following the initial installation. A 3% discount rate was used for
  the analysis reported in this table, see the TEDD for the analysis
  with a 7% discount rate.

B. Economic Impact Methodologies

    EPA devised a set of tests for analyzing economic achievability. As
is often the practice, EPA conducted a cost-to-revenue analysis to
examine the relationship between the costs of the proposed rule to
current (or pre-rule) dental office revenues. In addition, EPA chose to
examine the financial impacts of the proposed rule using two measures
that utilize the data EPA has on dental office baseline assets and
estimated replacement capital costs: (1) Ratio of the Proposed Rule's
Capital Costs to Total Dental Office Capital Assets and (2) Ratio of
the Proposed Rule's Capital Costs to Annual Dental Office Capital
Replacement Costs.
    EPA did not conduct a traditional closure analysis for this
proposed rule because EPA does not have detailed data on baseline
financial conditions of dental offices. Also, closure analyses
typically rely on accounting measures such as present value of after-
tax cash flow. However, such accounting measures are difficult to
implement for businesses that are organized as sole proprietorships or
partnerships, as is the case in the dental industry. Still, the 2007
Economic Census reports that approximately 700 offices of the
approximately 110,000 total offices had revenue of less than $25,000
(2007 dollar basis). In reviewing the implied operating characteristics
of these low revenue offices, EPA considered whether these offices
should be excluded from the analyses on any of the following bases:
     These low revenue offices could be single-dentist and/or
part-time businesses that provide services as a subcontractor on an
independent fee-for-service basis, such as dental hygiene, in general
service dental offices that are owned and operated by a larger dental
practice. Because these establishments would not be the primary owner/
operator of the dental offices in which they provide services, they
would not directly incur the compliance costs of a Dental Amalgam Rule.
If they incurred any of these costs, it would be on a limited
fractional share basis, most likely in proportion to the total value of
their services as a fraction of the total revenue in the office. On the
other hand, if these operators offer their services in a competitive
market, it may be that none of the compliance costs are shared by these
subcontractors.
     Another possibility is these very low revenue offices
could be non-profit groups which provide pay-as-you-can or free
services to a low-income populations. In this case, these small
businesses may be viable enterprises because they receive in-kind
donations not counted as revenue, e.g., services of a practicing
dentist.
     Alternatively, these low revenue offices may be non-viable
as for-profit businesses, if they are attempting to operate as general
service dental practices. This is based on EPA's assessment (see Ratio
of Proposed Rule Capital Costs to Total Dental Office Capital
Replacement Costs, below) that 1-2 chair offices would incur pre-rule
capital replacement costs of approximately $23,500 per year. This cost
represents all or a substantial fraction of annual revenue of the
business in the below-$25,000 revenue range. Accordingly, these
businesses may not be operating viably as for-profit general service
dental offices.
    As such, EPA could consider these offices to be the equivalent of
baseline closures as traditionally accounted for in cost and economic
impact analysis for effluent guidelines rulemakings. As a result of the
uncertainty here, EPA analyzed the impacts twice: (1) Excluding dental
offices that could represent baseline closures and (2) including all
offices in the analysis. EPA solicits comment for additional
information on these low revenue dental offices.
1. Cost-to-Revenue Analysis
    To provide an assessment of the impact of the rule on dental
offices, EPA used a cost-to-revenue analysis as is standard practice
for ELGs when looking at impacts to small businesses. The cost-to-
revenue analysis compares the total annualized compliance cost of each
regulatory option with the revenue of the entities. It is also used
under the Regulatory Flexibility Act (RFA) to determine if a rule has
the potential to have a significant impact on a substantial number of
small entities. EPA apportioned all dental offices into Economic Census
revenue ranges. Using the relationship between revenue and number-of-
chairs previously developed, each revenue range was assigned to a
number-of-chairs category which determined its annual costs. EPA looked
at whether all, some, or none of the offices in each revenue range
would exceed the 1% or 3% threshold (to signal the potential for
significant impact), and summed across chair-size categories to assess
impact to the industry. To incorporate the discussion of low revenue
dental offices described in Section XVI.B above, this analysis is
conducted twice: (1) Excluding dental offices that could represent
baseline closures and (2) including all offices in the analysis.
2. Ratio of the Proposed Rule's Capital Costs to Total Dental Office
Capital Assets
    This ratio examines the initial spending on capital costs of
compliance in relation to the baseline value of assets on the balance
sheet of dental office businesses. EPA assumes a low ratio implies
limited impact on dental offices' ability to finance the initial
spending on capital costs of the proposed rule. A high ratio may still
allow costs to be financed but could imply a need to change capital
planning and budgeting. EPA relied on data from Risk Management
Association (RMA) \23\ to estimate the average asset-to-sales ratio

in each number-of-chairs category for the dental office sector. This
ratio was then applied to the revenue range/number-of-chairs categories
to find an asset value for the minimum (reported as low in Table XVI-3)
and maximum (reported as high in Table XVI-3) revenue values for that
number-of-chairs category. EPA used these baseline assets by number-of-
chairs category as the denominator for the ratio. Total proposed rule
compliance costs, as described in Section XVI.B above, were assigned to
each number-of-chairs category as the numerator for the ratio. To
incorporate the discussion of low revenue dental offices described in
Section XVI.B above, this analysis is conducted twice: (1) Excluding
dental offices that could represent baseline closures, and (2)
including all offices in the analysis. This analysis assumes a minimum
revenue value of $5,000 for the lowest revenue range to prevent
division by zero.
---------------------------------------------------------------------------

    \23\ Risk Management Association reports financial statement
information received from lending institutions, for businesses in a
wide range of economic sectors, including Dental Offices. These data
include a wide range of income statement and balance sheet
information as well as financial and operating ratios.
---------------------------------------------------------------------------

    The RMA data contains the limitation that it may not be fully
representative of all dental offices, because it only represents dental
offices that are successful borrowers. It is possible that offices that
are not financially healthy may be underrepresented in the RMA data.
This would tend to understate EPA's finding of impacts.
3. Comparison of the Proposed Rule's Capital Costs to Annual Dental
Office Capital Replacement Costs
    EPA also compared the initial spending on capital costs of
compliance associated with this proposed rule to the estimated capital
replacement costs for a dental office business (e.g., computer systems,
chairs, x-ray machines, etc.). The capital replacement costs represent
a value that dental offices may reasonably expect to spend in any year
to replace and/or upgrade dental office capital equipment. EPA assumes
a low ratio implies limited impact on dental offices' ability to
finance the initial spending on capital costs of the proposed rule. A
high ratio may still allow costs to be financed but could imply a need
to change capital planning and budgeting. However, because EPA expects
that annual dental office capital replacement would be smaller than
total dental office capital assets, this ratio is likely to result in a
higher value than the previous ratio. Because this ratio is based on a
different data source, it provides an independent check that abstracts
from the limitations of the RMA data.
    EPA used data from Safety Net Dental Clinic Manual, prepared by the
National Maternal & Child Oral Health Resource Center at Georgetown
University (see DCN DA00143). This study examines data describing the
equipment needs and costs for starting a dental practice for a range of
different number-of-chairs including information on the life of the
dental equipment. EPA then used these data to estimate capital
replacement costs, accounting for the total value of equipment
purchases for different numbers of chairs, and the composition of
purchases by equipment life category. EPA used these replacement
capital costs by number-of-chairs as the denominator for the ratio.
Total proposed rule compliance costs, as described in Section XVI.B
above, were assigned to each number-of-chairs as the numerator for the
ratio.
    Because the data are for starting a dental clinic instead of a
dental practice, EPA is taking comment to solicit additional
information on equipment needs and costs for starting a dental
practice, including information on the life of the dental equipment.
See the TEDD for details on this analysis.

C. Results of Impact Analysis

1. Cost-to-Revenue Analysis Results
    Following the methodology outlined in XVI.B, EPA estimated the
occurrence of annualized compliance costs exceeding the 1% and 3% of
revenue thresholds for the proposed option twice: (1) Excluding dental
offices that could represent baseline closures, and (2) including all
offices in the analysis.
    Table XVI-2 summarizes the results from this analysis. As shown
there, under either scenario, over 99% of dentists would incur
annualized compliance costs of less than 1% of revenue. With baseline
set-asides excluded from the analysis, 507 offices (0.5% of offices
using dental amalgam and exceeding the set-aside revenue threshold) are
estimated to incur costs exceeding 1% of revenue; no offices are
estimated to incur costs exceeding 3% of revenue. With baseline set-
asides included in the analysis, 965 offices (0.9% of offices using
dental amalgam) are estimated to incur costs exceeding 1% of revenue;
221 offices (0.2% of offices using dental amalgam) are estimated to
incur costs exceeding 3% of revenue.

                              Table XVI-2--Cost-to-Revenue Analysis Impact Summary
----------------------------------------------------------------------------------------------------------------
                                                         Costs >1% Revenue               Costs >3% Revenue
        Number of chairs           Total offices ---------------------------------------------------------------
                                   by chair size      Number          Percent         Number          Percent
----------------------------------------------------------------------------------------------------------------
                               Excluding Baseline Set-Aside Offices from Analysis
----------------------------------------------------------------------------------------------------------------
1-2 chairs......................          12,197             507             4.2               0             0.0
3 chairs........................          25,835               0             0.0               0             0.0
4 chairs........................          27,976               0             0.0               0             0.0
5 chairs........................          15,194               0             0.0               0             0.0
6 chairs........................          12,047               0             0.0               0             0.0
7+ chairs.......................          16,611               0             0.0               0             0.0
                                 -------------------------------------------------------------------------------
    Total.......................         109,859             507             0.5               0             0.0
----------------------------------------------------------------------------------------------------------------
                                Including Baseline Set-Aside Offices in Analysis
----------------------------------------------------------------------------------------------------------------
1-2 chairs......................          12,197             965             7.9             221             1.8
3 chairs........................          25,835               0             0.0               0             0.0
4 chairs........................          27,976               0             0.0               0             0.0
5 chairs........................          15,194               0             0.0               0             0.0
6 chairs........................          12,047               0             0.0               0             0.0
7+ chairs.......................          16,611               0             0.0               0             0.0
                                 -------------------------------------------------------------------------------

    Total.......................         109,859             965             0.9             221             0.2
----------------------------------------------------------------------------------------------------------------
Source: EPA analysis.

2. Ratio of the Proposed Rule's Capital Costs to Total Dental Office
Capital Assets
    Table XVI-3 reports the findings from this analysis, specifically
the weighted average of the initial spending on the proposed rule's
capital costs divided by total assets of dental office across the
revenue range/number-of-chairs analysis combinations. With baseline
set-asides excluded from the analysis, the resulting initial capital
costs to total capital assets values are low, with an average value
0.5% to 1.0% for the no technology in-place case and 0% for the
technology in-place case. With baseline closures included in the
analysis, the resulting initial capital costs to total capital assets
values are low, with an average value 0.6% to 1.2% for the no
technology in-place case and 0% for the technology in-place case.

         Table XVI-3--Initial Spending as Percentage of Pre-Rule Total Dental Office Capital Assets \1\
----------------------------------------------------------------------------------------------------------------
                                                                 Technology in place     No technology in place
                      Number of chairs                       ---------------------------------------------------
                                                                  Low          High         Low          High
----------------------------------------------------------------------------------------------------------------
                            Excluding Baseline Set-Aside Establishments from Analysis
----------------------------------------------------------------------------------------------------------------
1-2 chairs..................................................          0.1          0.1          2.7          1.3
3 chairs....................................................          0.0          0.0          0.8          0.5
4 chairs....................................................          0.0          0.0          0.5          0.3
5 chairs....................................................          0.0          0.0          0.3          0.2
6 chairs....................................................          0.0          0.0          0.3          0.2
7+ chairs...................................................          0.0          0.0          0.2          0.2
Weighted Average............................................          0.0          0.0          0.7          0.4
----------------------------------------------------------------------------------------------------------------
                             Including Baseline Set-Aside Establishments in Analysis
----------------------------------------------------------------------------------------------------------------
1-2 chairs..................................................          0.2          0.1          3.7          1.7
3 chairs....................................................          0.0          0.0          0.8          0.5
4 chairs....................................................          0.0          0.0          0.5          0.3
5 chairs....................................................          0.0          0.0          0.3          0.2
6 chairs....................................................          0.0          0.0          0.3          0.2
7+ chairs...................................................          0.0          0.0          0.2          0.2
Weighted Average............................................          0.0          0.0          0.8          0.5
----------------------------------------------------------------------------------------------------------------
\1\ EPA used the baseline asset value for the minimum (reported as low) and maximum (reported as high) revenue
  values by number-of-chairs category as the denominator for the ratio. Total proposed rule compliance costs, as
  described in Section XVI.B above, were assigned to each number-of-chairs category as the numerator for the
  ratio.

3. Ratio of the Proposed Rule's Capital Costs to Annual Dental Office
Capital Replacement Costs Results
    EPA compared the estimated total initial spending on the proposed
rule's capital costs to the estimated capital replacement costs across
all chair-sizes. The resulting values for the proposed option range
from 2.9% to 3.5%, with a weighted average of 2.9% across all chair
size ranges.

 Table XVI-4--Initial Spending as Percentage of Estimated Annual Dental
                  Office Capital Replacement Costs \1\
------------------------------------------------------------------------
                      Number of chairs                         Percent
------------------------------------------------------------------------
1-2 chairs.................................................          3.4
3 chairs...................................................          3.2
4 chairs...................................................          2.6
5 chairs...................................................          2.2
6 chairs...................................................          2.9
7 chairs...................................................          3.5
8 chairs...................................................          3.1
9 chairs...................................................          2.9
Weighted Average...........................................          2.9
------------------------------------------------------------------------
Source: EPA Analysis.
\1\ EPA estimated capital replacement costs, accounting for the total
  value of equipment purchases for different numbers of chairs, and the
  composition of purchases by equipment life category by number-of-
  chairs as the denominator for the ratio. Total proposed rule
  compliance costs, as described in Section XVI.B, were assigned to each
  number-of-chairs as the numerator for the ratio.

D. Economic Achievability

    The analyses performed above demonstrate the impact of this
proposed rule on the dental office sector. In the cost-to-revenue
analysis, EPA found that no more than 0.2% of offices, mostly in the
lower revenue ranges, would potentially incur costs in excess of 3% of
revenue. The two financial ratios reported in Tables XVI-3 and XVI-4
show that the proposed option would not cause dental offices to
encounter difficulty in financing initial spending on capital costs of
the proposed regulatory option. Based on the results of the three
analyses above in combination, and EPA's inability at this time to
conduct a traditional facility closure analysis, EPA has determined
that the proposed pretreatment standard is economically achievable. EPA
notes that, due to a lack of data, the economic

impact analyses did not include large institutional facilities.
However, the results of the economic analyses performed on a range of
office sizes indicate that this proposal is economically achievable at
every level. Therefore, EPA projects the rule would similarly be
achievable for large institutional facilities. EPA requests comment on
this projection and data to perform economic achievability analyses.

E. Economic Impact for New Sources

    EPA determined that this proposed pretreatment standard for new
sources would not impose a barrier to entry. EPA relied on data
describing the equipment needs and costs for starting a dental practice
as compiled in Safety Net Dental Clinic Manual, prepared by the
National Maternal & Child Oral Health Resource Center at Georgetown
University (see DCN DA00143). Information from the Georgetown Manual
demonstrates that the amalgam separator capital costs (based on costs
for existing model facilities as described in Section XI) comprised
0.3% to 0.4% of the cost of starting a dental practice and, therefore,
does not pose a barrier to entry.

 Table XVI-5--Initial Spending as Percentage of Estimated Dental Office
                             Start-Up Costs
------------------------------------------------------------------------
                      Number of chairs                         Percent
------------------------------------------------------------------------
1-2 chairs.................................................          0.4
3 chairs...................................................          0.4
4 chairs...................................................          0.3
5 chairs...................................................          0.3
6 chairs...................................................          0.3
7 chairs...................................................          0.4
8 chairs...................................................          0.4
9 chairs...................................................          0.3
Weighted Average...........................................          0.3
------------------------------------------------------------------------
Source: EPA Analysis.

XVII. Pollutant Reductions to POTWs and Surface Waters

    Consistent with its costing methodology, EPA's pollutant reduction
methodology assumes 2008 ISO 11143 amalgam separators on the market
today with BMPs, the proposed technology basis, would be used to comply
with this proposed rule. As was the case for costing, EPA does not have
office specific discharge data for the approximately 110,000 dental
offices potentially subject to this proposal. Instead, EPA has modeled
the discharges of mercury based on nationwide estimates of amalgam
restorations and removals, and did not calculate the pollutant
reductions on a per office basis. Rather, EPA calculated average
mercury loadings by dividing the total number of annual procedures by
the total number of dentists performing the procedure.\24\ This is the
same approach and data that EPA presented in its Health Services
Industry Detailed Study (EPA 821-R-08-014). EPA did not receive
comments on this part of the health study that would cause EPA to
reconsider its approach, and, therefore, EPA did not change the overall
methodology. The following sections describe the method in more detail.
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    \24\ Because this approach is based on the number of dentists,
it includes those dentists both at offices and institutional
facilities.
---------------------------------------------------------------------------