Effluent Limitations Guidelines and Standards for the Dental Category, 27154-27178 [2017-12338]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 82, Number 113 (Wednesday, June 14, 2017)]
[Rules and Regulations]
[Pages 27154-27178]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-12338]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 441

[EPA-HQ-OW-2014-0693; FRL-9957-10-OW]
RIN 2040-AF26


Effluent Limitations Guidelines and Standards for the Dental 
Category

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The Environmental Protection Agency (EPA) is promulgating 
technology-based pretreatment standards under the Clean Water Act to 
reduce discharges of mercury from dental offices into municipal sewage 
treatment plants known as publicly owned treatment works (POTWs). This 
final rule requires dental offices to use amalgam separators and two 
best management practices recommended by the American Dental 
Association (ADA). This final rule includes a provision to 
significantly reduce and streamline the oversight and reporting 
requirements in EPA's General Pretreatment Regulations that would 
otherwise apply as a result of this rulemaking. EPA expects compliance 
with this final rule will annually reduce the discharge of mercury by 
5.1 tons as well as 5.3 tons of other metals found in waste dental 
amalgam to POTWs.

DATES: The final rule is effective on July 14, 2017. The compliance 
date, meaning the date that existing sources subject to the rule must 
comply with the standards in this rule is July 14, 2020. After the 
effective date of the rule, new sources subject to this rule must 
comply immediately with the standards in this rule. In accordance with 
40 CFR part 23, this regulation shall be considered issued for purposes 
of judicial review at 1 p.m. Eastern time on June 28, 2017. Under 
section 509(b)(1) of the CWA, judicial review of this regulation can be 
had only by filing a petition for review in the U.S. Court of Appeals 
within 120 days after the regulation is considered issued for purposes 
of judicial review. Under section 509(b)(2), the requirements in this 
regulation may not be challenged later in civil or criminal proceedings 
brought by EPA to enforce these requirements.

ADDRESSES: EPA has established a docket for this action under Docket ID 
No. EPA-HQ-OW-2014-0693. All documents in the docket are listed on the 
https://www.regulations.gov Web site. 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, is not placed on the Internet 
and will be publicly available only in hard copy form. This material 
can be viewed 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 202-566-1744, and the 
telephone number for the Water Docket is 202-566-2426. Publicly 
available docket materials are available electronically through https://www.regulations.gov. A detailed record index, organized by subject, is 
available on EPA's Web site at https://www.epa.gov/eg/dental-effluent-guidelines .

FOR FURTHER INFORMATION CONTACT: For more information, see EPA's Web 
site: https://www.epa.gov/eg/dental-effluent-guidelines. For technical 
information, contact Ms. Karen Milam, Engineering and Analysis Division 
(4303T), Office of Water, Environmental Protection Agency, 1200 
Pennsylvania Ave. NW., Washington, DC 20460-0001; telephone: 202-566-
1915; email: milam.karen@epa.gov.

SUPPLEMENTARY INFORMATION:

I. Regulated Entities and Supporting Information
    A. Regulated Entities
    B. Supporting Information
II. Legal Authority
III. Executive Summary
IV. Background
    A. Legal Framework
    1. Clean Water Act
    2. Effluent Limitations Guidelines and Standards
    a. Best Available Technology Economically Achievable (BAT)
    b. Best Available Demonstrated Control Technology (BADCT)/New 
Source Performance Standards (NSPS)
    c. Pretreatment Standards for Existing Sources (PSES)
    d. Pretreatment Standards for New Sources (PSNS)
    e. Best Management Practices (BMPs)
    B. Dental Sector Rulemaking History and Summary of Public 
Comments
    C. Existing State and Local Program Requirements
    D. Roles and Responsibilities Under the National Pretreatment 
Program

[[Page 27155]]

    E. Minamata Convention on Mercury
V. Description of Dental Industry & Dental Amalgam Wastewater 
Sources and Management
    A. Dental Industry
    B. Dental Amalgam Wastewater Sources and Management
    1. Amalgam Separators
    2. Polishing To Remove Dissolved Mercury From Wastewater
    3. Wastewater Retention Tanks
    4. Best Management Practices
VI. Final Rule
    A. Scope and General Applicability
    B. Existing Source (PSES) Option Selection
    C. New Source (PSNS) Option Selection
    D. Requirements
    1. Performance Standard
    2. Applicability to Dental Offices That Do Not Place or Remove 
Dental Amalgam
    3. Dental Discharger Reporting and On-Site Paperwork Compliance 
Requirements
    4. Control Authority Oversight/Reporting
    5. Interaction With Existing State and Local Mandatory Dental 
Amalgam Reduction Programs
    6. Variances
    E. Pollutants of Concern and Pass-Through Analysis
VII. Technology Costs
    A. Costs for Model Dental Offices
    B. Costs for Larger Institutional Dental Offices
VIII. Pollutant Loads
    A. National Estimate of Annual Pollutant Reductions to POTWs 
Associated With This Rule
    1. Mercury
    2. Other Metals
    3. Total Reductions
    B. National Estimate of Annual Pollutant Reductions to Surface 
Waters Associated With This Rule
IX. Economic Impact Analysis
    A. Social Cost Estimates
    B. Economic Impact
    1. Cost-to-Revenue Analysis
    2. Ratio of Rule's Capital Costs to Total Dental Office Capital 
Assets
    3. Comparison of the Rule's Capital Costs to Annual Dental 
Office Capital Replacement Costs
    C. Economic Achievability
X. Cost Effectiveness Analysis
XI. Environmental Assessment
    A. Environmental Impacts
    B. Environmental Benefits
XII. Non-Water Quality Environmental Impacts Associated With the 
Technology Basis of the Rule
    A. Energy Requirements
    B. Air Emissions
    C. Solid Waste Generation
XIII. Standards for Reference
XIV. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and 
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With 
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From 
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Energy Effects
    I. National Technology Transfer and Advancement Act
    J. Executive Order 12898: Federal Actions To Address 
Environmental Justice in Minority Populations and Low-Income 
Populations
    K. Congressional Review Act

I. Regulated Entities and Supporting Information

A. Regulated Entities

    Entities potentially regulated by this action include:

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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.
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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 or 
affected by this final rule. 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 final rule, you should carefully 
examine the applicability criteria listed in Sec.  441.10 and the 
definitions in Sec.  441.20 of this final rule and detailed further in 
Section VI of this preamble. If you still have questions regarding the 
applicability of this final rule to a particular entity, consult the 
person listed for technical information in the preceding FOR FURTHER 
INFORMATION CONTACT section.

B. Supporting Information

    This final rule is supported by a number of documents including the 
Technical and Economic Development Document for the Final Effluent 
Limitations Guidelines and Standards for the Dental Category (TEDD), 
Document No. EPA-821-R-16-005. The TEDD and additional records are 
available in the public record for this final rule and on EPA's Web 
site at https://www.epa.gov/eg/dental-effluent-guidelines.

II. Legal Authority

    EPA promulgates 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.

III. Executive Summary

    The purpose of this final rule is to set a uniform national 
standard that will greatly reduce the discharge of mercury-containing 
dental amalgam to municipal sewage treatment plants, known as POTWs, in 
the United States. Mercury is a potent neurotoxin that bioaccumulates 
in fish and shellfish, and mercury pollution is widespread and a global 
concern that originates from many diverse sources such as air 
deposition from municipal and industrial incinerators and combustion of 
fossil fuels. Across the U.S., 12 states and at least 18 localities 
have established mandatory programs to reduce discharges of mercury to 
POTWs. As a result of these efforts, along with outreach from the ADA 
to promote voluntary actions to reduce such discharges, approximately 
40 percent of the dentists subject to this rule already have installed 
amalgam separators. Amalgam separators greatly reduce the discharge of 
mercury-containing amalgam to POTWs. Amalgam separators are a 
practical, affordable and readily available technology for capturing 
mercury at dental offices. The mercury collected by these separators 
can be recycled. This rule will ensure that mercury discharges to POTWs 
are effectively controlled at dental offices that discharge wastewater 
to POTWs.
    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 Evaluation Final Report (DCN 
DA00006) prepared by the Association of Metropolitan Sewerage Agencies 
(AMSA), dental offices are the main source of mercury discharges to 
POTWs. A study funded by the ADA published in 2005 estimated that 
dental offices contributed 50 percent of mercury entering POTWs (DCN 
DA00163). Mercury is discharged in the form of waste dental amalgam 
when dentists remove old amalgam fillings from cavities, and from 
excess amalgam

[[Page 27156]]

waste when a dentist places a new amalgam filling.
    While dental offices are not a major contributor of mercury to the 
environment generally, dental offices are the main source of mercury 
discharges to POTWs. EPA estimates that across the United States 5.1 
tons of mercury and an additional 5.3 tons of other metals found in 
waste dental amalgam are collectively discharged into POTWs annually. 
Mercury entering POTWs frequently partitions into the sludge, the solid 
material that remains after wastewater is treated. Mercury from waste 
amalgam therefore can make its way into the environment from the POTW 
through the incineration, landfilling, or land application of sludge or 
through surface water discharge. Once released into the aquatic 
environment, certain bacteria can change mercury into methylmercury, a 
highly toxic form of mercury that bioaccumulates in fish and shellfish. 
In the U.S., consumption of fish and shellfish is the main source of 
methylmercury exposure to humans. Removing mercury when it is in a 
concentrated and easy to manage form in dental amalgam, before it 
becomes diluted and difficult and costly to remove, is a common sense 
step to prevent mercury from being released into the environment where 
it can become a hazard to humans.
    The ADA, which supported removal and recycling of mercury from 
wastewater discharged to POTWs in its comments on the 2014 proposed 
rule (See DCN EPA-HQ-OW-2014-0693-0434), developed best management 
practices (BMPs) to facilitate this goal and shared its recommendations 
widely with the dental community (DCN DA00165). The ADA's voluntary 
amalgam waste handling and disposal practices include the use of 
amalgam separators to reduce mercury discharges. In addition, some 
states and localities have implemented mandatory programs to reduce 
dental mercury discharges that include the use of amalgam separators.
    EPA has concluded that requiring dental offices to remove mercury 
through relatively low-cost and readily available amalgam separators 
and BMPs makes sense. Capturing mercury-laden waste where it is created 
prevents it from being released into the environment. This final rule 
controls mercury discharges to POTWs by establishing a performance 
standard for amalgam process wastewater based on the use of amalgam 
separator technology. The rule also requires dental dischargers to 
adopt two BMPs, one which prohibits the discharge of waste (``or 
scrap''), and the other which prohibits the use of line cleaners that 
may lead to the dissolution of solid mercury when cleaning chair-side 
traps and vacuum lines.
    In addition, the rule minimizes the administrative burden on dental 
offices subject to the rule, as well as on federal, state, and local 
regulatory authorities responsible for oversight and enforcement of the 
new standard. Administrative burden was a concern of many of the 
commenters on the 2014 proposed rule and EPA has greatly reduced that 
burden through streamlining the administrative requirements in this 
final rule.
    When EPA establishes categorical pretreatment requirements, it 
triggers additional oversight and reporting requirements in EPA's 
General Pretreatment Regulations. The General Pretreatment Regulations 
specify that Control Authorities (which are often the state or POTW) 
are responsible for administering and enforcing pretreatment standards, 
including receiving and reviewing compliance reports. While other 
industries subject to categorical pretreatment standards typically 
consist of tens to hundreds of facilities, the dental industry consists 
of approximately 130,000 offices. Application of the default General 
Pretreatment Regulation oversight and reporting requirements to such a 
large number of facilities would be much more challenging. Further, 
dental office discharges differ from other industries for which EPA has 
established categorical pretreatment standards. Both the volume of 
wastewater discharged and the quantity of pollutants in the discharge 
on a per facility basis are significantly less than other industries 
for which EPA has established categorical pretreatment standards. 
Accordingly, this final rule exempts dental offices from the General 
Pretreatment Regulations' oversight and reporting requirements 
associated with categorical pretreatment standards, reflecting EPA's 
recognition that the otherwise-applicable regulatory framework for 
categorical dischargers would be unlikely to have a significant 
positive impact on overall compliance with the rule across the dental 
industry, while imposing a substantial burden on state and local 
regulating authorities.
    In order to simplify implementation and compliance for the dental 
offices and the regulating authorities, the final rule establishes that 
dental dischargers are not Significant Industrial Users (SIUs) as 
defined in 40 CFR part 403, and are not Categorical Industrial Users 
(CIUs) or ``industrial users subject to categorical pretreatment 
standards'' as those terms and variations are used in the General 
Pretreatment Regulations, unless designated such by the Control 
Authority. While this rule establishes pretreatment standards that 
require dental offices to reduce dental amalgam discharges, the rule 
does not require Control Authorities to implement the traditional suite 
of oversight requirements in the General Pretreatment Regulations that 
become applicable upon the promulgation of categorical pretreatment 
standards for an industrial category. This significantly reduces the 
reporting requirements for dental dischargers that would otherwise 
apply by instead requiring them to demonstrate compliance with the 
performance standard and BMPs through a one-time compliance report to 
their Control Authority. This regulatory approach also eliminates the 
additional oversight requirements for Control Authorities that are 
typically associated with SIUs, such as permitting and annual 
inspections of individual dental offices. It also eliminates additional 
reporting requirements for the Control Authorities typically associated 
with CIUs, such as identification of CIUs in their annual pretreatment 
reports. At the same time, the final rule recognizes the Control 
Authority's discretionary authority to treat a dental discharger as an 
SIU and/or CIU if, in the Control Authority's judgement, it is 
necessary.
    EPA estimated the annual costs associated with this rule. EPA's 
analysis reflects that many dental offices have already taken steps to 
reduce dental amalgam discharges by discontinuing the use of dental 
amalgam, adopting the ADA's voluntary best practices, or by meeting 
existing mandatory state or local requirements. On a national basis, 
EPA estimates that approximately 40 percent of dental offices subject 
to this final rule already use amalgam separators (DCN DA00456). Of the 
remaining 60 percent of dental offices that do not have amalgam 
separators and that are subject to this final rule, EPA estimates that 
20 percent do not place or remove dental amalgam (DCN DA00161). These 
dentists that do not place or remove dental amalgam--which correspond 
to 12 percent of the dental offices subject to this final rule--will 
incur little to no costs as a result of the rule. EPA estimates the 
remainder (representing 48 percent of the dental offices subject to 
this final rule) will incur an approximate average annual cost of $800 
per office. The total annual cost of this final rule is projected to be 
$59-$61 million.
    This final rule will produce human health and ecological benefits 
by reducing the estimated annual

[[Page 27157]]

nationwide POTW discharge of dental mercury to surface water from 1,003 
pounds to 11 pounds. Studies show that decreased point-source 
discharges of mercury to surface water have resulted in lower 
methylmercury concentrations in fish, and that such reductions can 
result in quantifiable economic benefits from improved human health and 
ecological conditions (DCN DA00148). While not quantified, as noted 
above, this rule will also reduce mercury releases to the environment 
associated with the incineration, landfilling, or land application of 
POTW sludges. Instead, EPA expects all of the collected amalgam will be 
recycled, rather than released back into the environment.

IV. Background

A. Legal Framework

1. Clean Water Act
    Congress passed the Federal Water Pollution Control Act Amendments 
of 1972, also known as the Clean Water Act (CWA), 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 
establishes a two- pronged approach for these permits: Technology-based 
controls that establish the floor of performance for all dischargers, 
and water quality-based limits where the technology-based limits are 
insufficient for the discharge to meet applicable water quality 
standards. To serve as the basis for the technology-based controls, the 
CWA authorizes EPA to establish national technology-based effluent 
limitations guidelines and new source performance standards for 
discharges from different categories of point sources, such as 
industrial, commercial, and public sources, that discharge directly 
into waters of the U.S.
    Direct dischargers (those discharging directly to surface waters) 
must comply with effluent limitations in NPDES permits. Technology-
based effluent limitations in NPDES permits for direct dischargers 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 (CWA section 402(a)(1)(B) and 40 CFR 125.3). The effluent 
guidelines and new source performance standards established by 
regulation for categories of industrial dischargers are based on the 
degree of control that can be achieved using various levels of 
pollution control technology, as specified in the Act.
    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) as outlined in CWA section 304(a)(4) and 40 CFR 401.16; (2) toxic 
pollutants (e.g., toxic metals such as chromium, lead, mercury, nickel, 
and zinc) as outlined in section 307(a) of the Act, 40 CFR 401.15 and 
40 CFR part 423, appendix A; and (3) non-conventional pollutants, which 
are those pollutants that are not categorized as conventional or toxic 
(e.g., ammonia-N, formaldehyde, and phosphorus).
    The CWA also authorizes EPA to promulgate nationally applicable 
pretreatment standards that restrict pollutant discharges from 
facilities that discharge pollutants indirectly, by sending wastewater 
to POTWs, as outlined in sections 307(b), (c) and 304(g) of the CWA. 
EPA establishes national pretreatment standards for those pollutants 
that may pass through, interfere with, or may otherwise be incompatible 
with POTW operations. CWA sections 307(b) and (c) and 304(g). The 
legislative history of the 1977 CWA amendments explains that 
pretreatment standards are technology-based and analogous to 
technology-based effluent limitations for direct dischargers for the 
removal of toxic pollutants. As further explained in the legislative 
history, the combination of pretreatment and treatment by the POTW is 
intended to achieve the level of treatment that would be required if 
the industrial source were making a direct discharge. Conf. Rep. No. 
95-830, at 87 (1977), reprinted in U.S. Congress. Senate. Committee on 
Public Works (1978), A Legislative History of the CWA of 1977, Serial 
No. 95-14 at 271 (1978). As such, in establishing pretreatment 
standards, EPA's consideration of pass through for national technology-
based categorical pretreatment standards differs from that described in 
EPA's General Pretreatment regulations at 40 CFR part 403. 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. CWA 
301(b)(1)(A)(BPT); and 301(b)(1)(E).
2. Effluent Limitations Guidelines and Standards
    EPA develops Effluent Guidelines Limitations and Standards (ELGs) 
that are technology-based regulations for specific categories of 
dischargers. EPA bases these regulations on the performance of control 
and treatment technologies. The legislative history of CWA section 
304(b), which is the heart of the effluent guidelines program, 
describes the need to press toward higher levels of control through 
research and development of new processes, modifications, replacement 
of obsolete plants and processes, and other improvements in technology, 
taking into account the cost of controls. Congress has also stated that 
EPA need not consider water quality impacts on individual water bodies 
as the guidelines are developed; see Statement of Senator Muskie 
(October 4, 1972), reprinted in U.S. Senate Committee on Public Works, 
Legislative History of the Water Pollution Control Act Amendments of 
1972, Serial No. 93-1, at 170).
    There are standards applicable to direct dischargers (dischargers 
to surface waters) and standards applicable to indirect dischargers 
(dischargers to POTWs). The types of standards relevant to this 
rulemaking are summarized here.
a. Best Available Technology Economically Achievable (BAT)
    BAT represents the second level of stringency for controlling 
direct discharge of toxic and nonconventional pollutants. In general, 
BAT-based effluent guidelines and new source performance standards 
represent the best available economically achievable performance of 
facilities in the industrial subcategory or category. Following the 
statutory language, EPA considers the technological availability and 
the economic achievability in determining what level of control 
represents BAT. CWA section 301(b)(2)(A). Other statutory factors that 
EPA considers in assessing BAT are 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

[[Page 27158]]

Administrator deems appropriate. CWA section 304(b)(2)(B). The Agency 
retains considerable discretion in assigning the weight to be accorded 
these factors. Weyerhaeuser Co. v. Costle, 590 F.2d 1011, 1045 (D.C. 
Cir. 1978).
b. Best Available Demonstrated Control Technology (BADCT)/New Source 
Performance Standards (NSPS)
    NSPS reflect effluent reductions that are achievable based on the 
best available demonstrated control technology (BADCT). 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 BADCT for all pollutants (that is, 
conventional, nonconventional, and toxic 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. CWA section 306(b)(1)(B).
c. Pretreatment Standards for Existing Sources (PSES)
    Pretreatment standards apply to dischargers of pollutants to POTWs; 
Pretreatment Standards for Existing Sources are designed to prevent the 
discharge of pollutants to POTWs 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, and thus the Agency typically 
considers the same factors in promulgating PSES as it considers in 
promulgating BAT. See Natural Resources Defense Council v. EPA, 790 
F.2d 289, 292 (3rd Cir. 1986).
d. 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. In establishing pretreatment standards for 
new sources, the Agency typically considers the same factors in 
promulgating PSNS as it considers in promulgating NSPS (BADCT).
e. Best Management Practices (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.''))

B. Dental Category Effluent Guidelines Rulemaking History and Summary 
of Public Comments

    EPA published the proposed rule on October 22, 2014, and took 
public comment through February 20, 2015. During the public comment 
period, EPA received approximately 200 comments. EPA also held a public 
hearing on November 10, 2014. Administrative burden was a concern of 
many of the commenters on the 2014 proposed rule, particularly from 
regulatory authorities responsible for oversight and enforcement of the 
new standard. Commenters also provided additional information on 
amalgam separators (e.g., costs, models, and design) as well as 
information on some other approaches to reduce pollutant discharges 
from dentists. Commenters also offered ways to improve and/or clarify 
the proposed pretreatment standards, including the proposed numerical 
efficiency and operation and maintenance requirements. See DCN DA00516 
for these comments and EPA's responses.

C. Existing State and Local Program Requirements

    Currently, 12 states (Connecticut, Louisiana,\1\ Maine, 
Massachusetts, Michigan, New Hampshire, New Jersey, New Mexico, New 
York, Rhode Island, Vermont, and Washington) have mandatory programs to 
reduce dental mercury discharges. Additionally, at least 18 localities 
(located in California, Colorado, Ohio, and Wisconsin) similarly have 
mandatory dental amalgam reduction pretreatment programs. EPA analyzed 
readily available information about these programs and found 
commonalities (DCN DA00524). For example, all require the use of 
amalgam separators and most specify associated operating and 
maintenance requirements. The majority of these programs also require 
some type of best management practices, and at least a one-time 
compliance report to the regulating authority.
---------------------------------------------------------------------------

    \1\ Louisiana state requirements do not explicitly require 
dental offices to install amalgam separators; dental offices must 
follow BMPs recommended by the ADA in 1999. ADA added amalgam 
separators to the list of BMPs in 2008.
---------------------------------------------------------------------------

D. Roles and Responsibilities Under the National Pretreatment Program

    The National Pretreatment Program requires industrial dischargers 
that discharge to POTWs to comply with pretreatment standards. The 
General Pretreatment Regulations in 40 CFR part 403 establish roles and 
responsibilities for entities involved in the implementation of 
pretreatment standards. This section summarizes the roles and 
responsibilities of Industrial Users (IUs), Control Authorities, and 
Approval Authorities. For a detailed description, see the preamble for 
the proposed rule (79 FR 63279-63280; October 22, 2014).
    An IU is a nondomestic source of indirect discharge into a POTW, 
and in this rule is the dental discharger. The Control Authority may be 
the POTW, the state, or EPA, depending on whether the POTW or the state 
is approved by EPA to administer the pretreatment program. The Control 
Authority is the POTW in cases where the POTW has an approved 
pretreatment program. The Control Authority is the state, where the 
POTW has not been approved to administer the pretreatment program, but 
the state has been approved. The Control Authority is EPA where neither 
the POTW nor the state have been approved to administer the 
pretreatment program. The Approval Authority is the

[[Page 27159]]

State (Director) in an NPDES authorized state with an approved 
pretreatment program; or the EPA regional administrator in a non-NPDES 
authorized state or NPDES state without an approved state pretreatment 
program.
    Typically, an IU is responsible for demonstrating compliance with 
pretreatment standards by performing self-monitoring, submitting 
reports and notifications to its Control Authority, and maintaining 
records of activities associated with its discharge to the POTW. The 
Control Authority is the regulating authority responsible for 
implementing and enforcing pretreatment standards. The General 
Pretreatment Regulations require certain minimum oversight of IUs by 
Control Authorities. The required minimum oversight includes receipt 
and analysis of reports and notifications submitted by IUs, random 
sampling and analyzing effluent from IUs, and conducting surveillance 
activities to identify occasional and continuing non-compliance with 
pretreatment standards. The Control Authority is also responsible for 
taking enforcement action as necessary. For IUs that are designated as 
Significant Industrial Users (SIUs), Control Authorities must inspect 
and sample the SIU effluent annually, review the need for a slug 
control plan, and issue a permit or equivalent control mechanism. IUs 
subject to categorical pretreatment standards are referred to as 
Categorical Industrial Users (CIUs). The General Pretreatment 
Regulations define SIU to include CIUs. The Approval Authority is 
responsible for ensuring that POTWs comply with all applicable 
pretreatment program requirements. Among other things, the Approval 
Authority receives annual pretreatment reports from the Control 
Authority. These reports must identify which IUs are CIUs.

E. Minamata Convention on Mercury

    On November 6, 2013, the United States joined the Minamata 
Convention on Mercury, a new multilateral environmental agreement 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 offices 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. This final rule contributes to the 
U.S.'s efforts to meet the measures called for in the treaty.

V. Description of Dental Industry & Dental Amalgam Wastewater Sources 
and Management

A. Dental Industry

    The industry category affected by this final 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 2012 Economic Census, there are 133,221 U.S. 
dental offices owned or operated by 125,275 dental firms.\2\ Only 2 
percent of all dental firms are multi-unit, the rest are single-unit. 
The growth of the number of dental offices remained steady over the 
past decade with an average increase of 1 percent per year.
---------------------------------------------------------------------------

    \2\ A firm is a business organization, such as a sole 
proprietorship, partnership, or corporation.
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    The industry includes mostly small businesses with an estimated 
over 99 percent of all offices falling below the Small Business 
Administration (SBA) size standard ($7.5 million in annual revenue). 
Using Census Bureau data, EPA estimates an average revenue for offices 
at $787,190 per year with an average of 6.6 employees per 
establishment.
    According to ADA data, approximately 80 percent of the dental 
industry engages in general dentistry. Approximately 20 percent are 
specialty dentists such as periodontists, orthodontists, radiologists, 
maxillofacial surgeons, endodontists, or prosthodontists (DCN DA00460).
    Dentistry may also be performed at larger institutional dental 
offices (military clinics and dental schools). Since EPA does not know 
if these offices are included in the 2012 Economic Census data, EPA 
conservatively assumed the largest offices are not present in the data, 
and so added an estimate of 415 larger institutional dental offices 
across the nation. For the final rule, EPA updated this number based on 
comments received on the proposed rule.

B. Dental Amalgam Wastewater Sources and Management

    Dental amalgam consists of approximately 49 percent 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 percent silver, 9 percent tin, 6 percent copper, 
1 percent zinc and small amounts of indium and palladium (DCN DA00131).
    Sources of dental amalgam 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 cuspidor, or suctioned out of 
the patient's mouth. In addition to filling new cavities, dentists also 
remove old restorations that are worn or damaged. Removed restorations 
also may be rinsed into a cuspidor or suctioned out of the patient's 
mouth. Based on information in the record (DCN DA00456), removed 
restorations is the largest contributor of mercury in dental 
discharges.
    The second category of dental amalgam discharges occurs 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 dental amalgam to be discharged.
    The use of dental amalgam has decreased steadily since the late 
1970s as alternative materials such as composite resins and glass 
ionomers have become more widely available. Estimates show that 
placements of dental amalgam have decreased on average by about 2 to 3% 
per year (74 FR 38686; August 4, 2009). Based on this information, EPA 
estimates that mercury in dental amalgam discharges to POTWs will 
decrease by about half within the next 25 years. While the use of 
dental amalgam continues to decline, EPA estimates that approximately 2 
tons of mercury would continue to be discharged to POTWs in 2040.
    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

[[Page 27160]]

percent of dental amalgam particles from the wastewater stream (DCN 
DA00163). EPA identified three major technologies that capture dental 
amalgam waste, in addition to chair-side traps and vacuum pump filters, 
before it is discharged to the POTW: Separators, ion exchange, and 
wastewater containment systems. EPA also identified BMPs that have a 
significant impact on dental amalgam discharges.
1. Amalgam Separators
    An amalgam separator is a device designed to remove solids from 
dental office wastewater. Amalgam separators remove amalgam particles 
from the wastewater through centrifugation, sedimentation, filtration, 
or a combination of any of these methods. Practically all amalgam 
separators on the market today rely on sedimentation because of its 
effectiveness and operational simplicity.
    The vast majority of amalgam separators on the market today have 
been evaluated for their ability to meet the current American National 
Standards Institute's (ANSI) Standard for Amalgam Separators (ANSI/ADA 
Standard No. 108 for Amalgam Separators). This standard incorporates 
the International Organization for Standardization (ISO) Standard for 
Dental Amalgam Separators (https://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=42288).\3\ The current ISO 
standard for amalgam separators is ISO 11143. ISO established a 
standard for measuring amalgam separator efficiency by evaluating the 
retention of amalgam solids using specified test procedures in a 
laboratory setting. In order to meet the ISO standard, a separator must 
achieve 95 percent removal or greater of total solids. The ISO standard 
also includes certain design requirements and requirements for 
instructions for proper use and maintenance. For example, for non-
sedimentation amalgam separators, the ISO 11143 standard requires a 
warning system such as an auditory or visual sign to indicate when the 
separator's efficiency is compromised to ensure that the operator is 
aware that the separator is not operating optimally. For sedimentation 
separators, the requirement can be met by providing instructions that 
would allow the operator to ascertain the operating status of the 
amalgam separator.
---------------------------------------------------------------------------

    \3\ ANSI is the coordinator of the U.S. voluntary consensus 
standards system. An ISO document may be nationally adopted as an 
ANS as written or with modifications to its content that reflect 
technical deviations to the ISO standard that have been agreed upon 
through a consensus process. In other words, a consensus of U.S. 
experts, in an open and due process based environment, agreed that 
ISO 11143 with U.S. modifications is appropriate for adoption as an 
ANS.
---------------------------------------------------------------------------

    Based on reported removal efficiencies of a range of amalgam 
separators currently on the market that meet the ISO standard, 
separators obtain a median of 99 percent removal efficiency (see 
Chapter 7 of the TEDD) of total dental solids. 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 percent (DCN DA00008).
    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. The collected solids must be 
handled in accordance with federal, state and local requirements. EPA 
regulates the disposal of mercury-containing hazardous waste under the 
Resource Conservation and Recovery Act (RCRA). A mercury-containing 
waste can be considered hazardous in two ways: (1) As a listed 
hazardous waste; or (2) as a characteristic hazardous waste. Unused 
elemental mercury being discarded would be a listed hazardous waste 
(waste code U151). Persons who generate hazardous waste, such as a 
waste that exhibits the hazardous characteristics for mercury, are 
subject to specific requirements for the proper management and disposal 
of that waste. The federal RCRA regulatory requirements differ 
depending upon how much hazardous waste a site generates per month. 
Most dental practices generate less than 100 kilograms of non-acute 
hazardous waste per month and less than 1 kilogram of acute hazardous 
waste per month. Such facilities are therefore classified as ``Very 
Small Quantity Generators'' (VSQGs). VSQGs are not subject to most of 
the RCRA hazardous waste requirements.
    Many states have additional requirements for the handling of 
mercury, including waste dental amalgam. Chapter 6 of the TEDD provides 
additional details on the handling requirements for states that require 
dentists to control dental mercury dischargers. To facilitate 
compliance with state and local requirements, several amalgam separator 
manufacturers offer services that facilitate the transport of waste 
amalgam to facilities that separate mercury from other metals in dental 
amalgam and recycle the mercury, keeping it out of the environment. EPA 
recommends that dental dischargers take advantage of such services. In 
2012, ADA posted a directory of amalgam recyclers on its Web site. See 
DCN DA00468.
    For more information about amalgam separators, see the proposed 
rule (79 FR 63265; October 22, 2014).
2. Polishing To Remove Dissolved Mercury From Wastewater
    Mercury from dental amalgam in wastewater is present in both the 
particulate and dissolved form. The vast majority (>99.6 percent) is 
particulate (DCN DA00018). An additional process sometimes referred to 
as ``polishing'' uses ion exchange to remove dissolved mercury from 
wastewater. 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. For 
ion exchange to be most effective, the incoming wastewater must first 
be treated to remove solids. Then the wastewater needs to be oxidized 
(creating a charge on the amalgam particles) 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 and an oxidation process. The data available to EPA 
indicate that total additional mercury reductions with the addition of 
polishing are typically about 0.5 percent (DCN DA00164). This is not 
surprising since, as indicated above, dissolved mercury contributes 
such a small portion to the total amount of mercury in wastewater. In 
addition to polishing as described above, EPA is aware that vendors are 
developing amalgam separators with an improved resin for removing 
dissolved mercury. For additional discussion on polishing, see proposal 
(79 FR 63266; October 22, 2014).
3. Wastewater Retention Tanks
    Commenters on the proposed rule identified wastewater retaining 
tanks as a third technology to reduce mercury discharges from dental 
offices to POTWs. Where currently used, these systems collect and 
retain all \4\ amalgam process wastewater. The wastewater remains in 
the wastewater retention tank until it is pumped out of the tank and 
transferred to a privately owned wastewater treatment facility. This 
eliminates the discharge of amalgam process wastewater and the 
associated

[[Page 27161]]

pollutants from a dental office to a POTW.
---------------------------------------------------------------------------

    \4\ Dental offices using wastewater retention tanks must ensure 
that all amalgam process wastewater is collected by the wastewater 
retention tanks. Any uncollected amalgam process wastewater that is 
discharged to the POTW is subject to this rule.
---------------------------------------------------------------------------

4. Best Management Practices
    In addition to technologies, EPA also identified best management 
practices currently used in this industry (and included in the ADA 
BMPs) to reduce dental amalgam discharges. In particular, EPA 
identified two BMPs to control dental amalgam discharges that would not 
be captured by an amalgam separator and/or polishing unit. Oxidizing 
line cleaners can solubilize bound mercury. If oxidizing cleaners are 
used to clean dental unit water lines, chair side traps, or vacuum 
lines that lead to an amalgam separator, the line cleaners may 
solubilize any mercury that the separator has captured, resulting in 
increased mercury discharges. One BMP ensures the efficiency of amalgam 
separators by prohibiting use of oxidizing line cleaners including but 
not limited to, bleach, chlorine, iodine and peroxide, that have a pH 
lower than 6 or greater than 8.\5\
---------------------------------------------------------------------------

    \5\ Many alternatives use enzymatic or other processes that do 
not lead to the dissolution of mercury when used to clean chairside 
traps, and vacuum lines. See DCN DA00215.
---------------------------------------------------------------------------

    Flushing waste amalgam from chair-side traps, screens, vacuum pump 
filters, dental tools, or collection devices into drains also presents 
additional opportunities for mercury to be discharged from the dental 
office. The second BMP prohibits flushing waste dental amalgam into any 
drain.

VI. Final Rule

A. Scope and General Applicability

    Consistent with the proposal, dental offices that discharge to 
POTWs are within the scope of this final pretreatment rule.\6\ EPA 
solicited information in the proposal from the public on its 
preliminary finding that, with few exceptions, dental offices do not 
discharge wastewater directly to surface waters. EPA did not receive 
any comments containing data to contradict this finding. Therefore, EPA 
is not establishing any requirements for direct wastewater discharges 
from dental offices to surface waters at this time.
---------------------------------------------------------------------------

    \6\ The final rule does not apply to dental discharges to septic 
systems.
---------------------------------------------------------------------------

    The final rule applies to wastewater discharges to POTWs from 
offices where the practice of dentistry is performed, including large 
institutions such as dental schools and clinics; permanent or temporary 
offices, home offices, and facilities; and including dental offices 
owned and operated by federal, state, or local governments including 
military bases. The final rule does not apply to wastewater discharges 
from dental offices 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 are not expected to engage in the 
practice of amalgam restorations or removals, and are not expected to 
have any wastewater discharges containing dental amalgam.
    The final rule also does not apply to wastewater discharges to 
POTWs from mobile units. EPA proposed to apply the standards to mobile 
units (typically a specialized mobile self- contained van, trailer, or 
equipment from which dentists provide services at multiple locations), 
soliciting comments and data pertaining to them (79 FR 63261; October 
22, 2014). However, EPA is not establishing requirements for mobile 
units at this time because it has insufficient data to do so. EPA does 
not have, nor did commenters provide, data on the number, size, 
operation, or financial characteristics of mobile units. EPA also has 
minimal information on wastewater discharges from mobile units, and/or 
practices employed to minimize dental amalgam in such discharges. 
Therefore, any further evaluation of requirements for mobile units is 
not possible at this time, and the final rule requirements do not apply 
to mobile units.

B. Existing Source (PSES) Option Selection

    After considering all of the relevant factors and dental amalgam 
management approaches discussed in this preamble and TEDD, as well as 
public comments, EPA decided to establish PSES based on proper 
operation and maintenance of one or more ISO 11143 \7\ compliant 
amalgam separators and two BMPs--a prohibition on the discharge of 
waste (or ``scrap'') amalgam to POTWs and a prohibition on the use of 
line cleaners that are oxidizing or acidic and that have a pH higher 
than 8 or lower than 6. EPA finds that the technology basis is 
``available'' as that term is used in the CWA because it is readily 
available and feasible for all dental offices subject to this rule. 
Data in the record demonstrate that the technology basis is extremely 
effective in reducing pollutant discharges in dental wastewater to 
POTWs as the median efficacy of ISO compliant amalgam separators on the 
market in the U.S. is 99.3 percent. Moreover, ADA recommends that 
dentists use the technology on which this rule is based (ISO compliant 
amalgam separators and BMPs). Further, as described in Section III, EPA 
estimates that approximately 40 percent of dental offices potentially 
subject to this rule currently use amalgam separators on a voluntary 
basis or are in states or localities with laws requiring the use of 
amalgam separators. Many dentists have used amalgam separators and BMPs 
for at least a decade. 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 $800 \8\ per 
office. EPA's economic analysis shows that this rule is economically 
achievable (see Section IX). Finally, EPA also examined the incremental 
non-water-quality environmental impacts of the final pretreatment 
standards and found them to be acceptable. See Section XII.
---------------------------------------------------------------------------

    \7\ ISO 11143 Standard as incorporated and updated by ANSI 
Standard 108 (ANSI 108/ISO 11143 Standard).
    \8\ This estimate is based on the average annualized cost for 
dental offices that do not currently have an amalgam separator. See 
DCN DA00458.
---------------------------------------------------------------------------

    EPA did not establish PSES based on technologies that remove 
dissolved mercury such as polishing. EPA is not aware of any state or 
local regulations that require ion exchange or that require removal of 
dissolved mercury. Commenters raised operational concerns with ion 
exchange citing a pilot study for the department of Navy. EPA also 
lacks adequate performance data to assess the efficacy of polishing for 
nationwide use. 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 traditional 
amalgam separators and polishing. Moreover, current information 
suggests that polishing is not available for nationwide use because the 
typical dental office may not have adequate space to install the 
treatment train needed for effective polishing and because there are 
few polishing systems on the market today in comparison to traditional 
amalgam separators. Lastly, EPA estimates that the capital costs of the 
polishing system, as a stand-alone system, are approximately four times 
that of the amalgam separator even though the costs for chemical use, 
regenerating the resin, filter replacement, and other operational costs 
were not reported (DCN DA00122). These factors led EPA to find that 
polishing is not ``available'' as that term is used in the CWA.

[[Page 27162]]

    EPA also did not establish PSES based on wastewater retention 
tanks. Capital costs for wastewater retention tanks are approximately 
twice that of the amalgam separator (DCN DA00461). EPA does not have 
information on the costs incurred by the dental office to send the 
collected wastewater off-site to a privately owned treatment facility 
(may also be referred to as a centralized waste treatment facility or 
CWT). Furthermore, wastewater retention tanks require space, and EPA 
determined that the typical dental office may not have adequate space 
to install the tanks. In addition, EPA is only aware of one vendor 
currently offering this technology and service combination (vendor 
transfers the collected wastewater to a privately owned treatment 
facility), and the vendor's service area is limited to a few states. 
Therefore, EPA did not find this technology to be available to the 
industry as a whole.

C. New Source (PSNS) Option Selection

    After considering all of the relevant factors and technology 
options discussed in this preamble and in the TEDD, as well as public 
comments, EPA decided to establish PSNS based on the same technologies 
identified above as PSES. As previously noted, under section 307(c) of 
the CWA, new sources of pollutants into POTWs must comply with 
standards that 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. The technologies used to control 
pollutants at existing offices, amalgam separators and BMPs, are fully 
available to new offices. In addition, data from EPA's record show that 
the incremental cost of an amalgam separator compared to the cost of 
opening a new dental office is negligible; therefore, EPA determined 
that the final PSNS present no barrier to entry (see Section IX below). 
Similarly, because EPA projects that the incremental non-water quality 
environmental impacts associated with controls for new sources would 
not exceed those for existing sources, EPA concludes the non-water 
quality environmental impacts are acceptable. Therefore, this final 
rule establishes PSNS that are the same as those for PSES.
    EPA rejected other technologies as the basis for PSNS for the same 
reasons the Agency rejected other technology bases for PSES.

D. Requirements

1. Performance Standard
    EPA finalized the performance standards based on the same 
technology identified in the proposed rule, amalgam separators.
    EPA proposed a standard that would require dental dischargers to 
remove a specified percentage of total mercury from amalgam process 
wastewater and to follow the BMPs. Recognizing the impracticality of 
collecting and analyzing wastewater samples to demonstrate compliance 
with the standard for this industry, EPA included a provision by which 
dental offices could demonstrate compliance by certifying they were 
following the required BMPs and using an amalgam separator that 
achieved the specified percentage when tested for conformance with the 
ISO standard. EPA received comments regarding the proposed requirement. 
Commenters questioned the specified percent reduction, and raised 
concerns that the proposed standard could require dental offices to 
measure the percent removal being achieved by their amalgam separator, 
which was not the Agency's intent. In response to these comments, the 
final rule specifies a performance standard--BMPs and the use of an 
amalgam separator(s) compliant with the ISO standard rather than 
specifying a numerical reduction requirement. The final rule also 
includes a provision such that the performance standard can be met with 
the use of an amalgam removing technology other than an amalgam 
separator (equivalent device). EPA included this provision to 
incorporate future technologies that achieve comparable removals of 
pollutants from dental discharges as amalgam separators but that may 
not fall under the amalgam separator classification. Because the rule 
does not include a numerical limit, the performance standards also 
specify certain operation and maintenance requirements for the amalgam 
separator or comparable device to ensure they are operated optimally.
    The final rule allows dental offices to continue to operate 
existing amalgam separators for their lifetime or ten years (whichever 
comes first), as long as the dental discharger complies with the other 
rule requirements including the specified BMPs, operation and 
maintenance, reporting, and recordkeeping requirements. Once the 
separator needs to be replaced or the ten-year period has ended, dental 
offices will need to replace the amalgam separator with one that meets 
the requirements of the final rule. EPA does not want to penalize 
existing dental offices or institutional dental offices that have 
already installed amalgam separators voluntarily or to comply with 
state or local requirements. EPA recognizes that these offices may 
currently have amalgam separators in place that do not meet the ANSI 
ADA specification or the criteria of the ISO 11143 2008 standard. EPA 
did not want to establish a rule that would require dental offices with 
existing separators that still have a remaining useful life to be 
retrofitted with new separators, both because of the additional costs 
incurred by dental offices that adopted technology to reduce mercury 
discharges ahead of EPA's requirements and because of the additional 
solid waste that would be generated by disposal of the existing 
separators.
    In addition to installing one or more amalgam separators compliant 
with the ISO 11143 standard (or its equivalent) and implementing the 
required BMPs, the pretreatment standards specify certain operating and 
maintenance requirements for the amalgam separator. For example, the 
final rule requires a documented amalgam separator inspection to ensure 
the separator is performing properly. As explained in Section V, 
malfunctioning separators or separators that have reached their 
capacity are ineffective. Therefore, in order to ensure that mercury is 
not discharged from the facility, it is important that dentists know 
the operational status of their amalgam separator (see 40 CFR 
441.40(c)). As such, the final rule requires the separator to be 
inspected per the manufacturer's instructions. In addition, as 
explained in Section V, the ISO standard specifies non-sedimentation 
separators must have a visual or auditory warning indicator when the 
separator is nearly full or operating in by-pass mode. While not 
required for sedimentation amalgam separators, some manufacturers of 
sedimentation amalgam separators include visual or auditory warning 
indicators. Because warning indicators make it easy to detect when the 
separator is not operating optimally, EPA encourages dental offices to 
select an amalgam separator with a warning indicator when installing a 
new amalgam separator.
    EPA is aware that some amalgam separator vendors (in addition to 
providing the needed equipment) or service providers offer service 
contracts to maintain the system. These vendors also typically provide 
waste

[[Page 27163]]

management services for the collected solids. Some vendors also provide 
the necessary documentation and reports required by existing state and 
local programs. EPA encourages but does not require dental offices to 
consider such services, as they may aid compliance with the rule.
2. Applicability to Dental Offices That Do Not Place or Remove Dental 
Amalgam
    In the final rule, dental dischargers that do not place dental 
amalgam, and do not remove dental amalgam except in limited emergency 
or unplanned, unanticipated circumstances are exempt from any further 
requirements as long as they certify such in their One-time Compliance 
Report to their Control Authority. In this way, if, over time, the use 
of dental amalgam is phased out as a restorative material, the 
requirements of this rule will no longer apply. By limited 
circumstances, EPA means, dental offices that remove amalgam at a 
frequency less than five percent of its procedures. As described below, 
based on the record, on average, this percent approximates to 9 
removals per office per year (DCN DA00467).
    Dental amalgam traditionally has been used as a restorative 
material for cavities because the malleability of newly mixed amalgam 
makes it easy to place into cavities and because of its durability over 
time. While still used in many dental offices in the U.S., some dental 
offices have elected not to use dental amalgam and instead use only 
non-mercury based filling materials, such as composite resins and glass 
ionomer cements (DCN DA00495). As explained in Section IV, removed 
restorations are the largest contributor of mercury in dental 
discharges. Some dental offices have also elected not to remove amalgam 
restorations.
    EPA recognizes some dental offices only remove dental amalgam 
extremely infrequently, where there is an unplanned, unanticipated 
procedure. At the same time, for accepting new patients during the 
normal course of business, EPA would expect offices to inquire as to 
whether the patient has mercury fillings and not accept patients that 
have such fillings unless they install a separator or equivalent 
treatment in accordance with this rule. EPA proposed that dental 
offices that certify that they do not place or remove amalgam except in 
limited emergency circumstances would be exempt from any further 
requirements of the rule. EPA is clarifying in the final rule that the 
limited circumstances provision applies to the removal, but not to the 
placement of dental amalgam. A dental office that stocks amalgam 
capsules clearly intends to place amalgam, and does not represent the 
type of limited circumstance this provision is intended to address. 
Commenters largely supported this approach, and most commenters 
suggested EPA define limited emergency circumstances. The frequency 
recommended by these commenters ranged from once a quarter to 96 times 
a year (DCN DA00467).
    EPA is including the limited circumstances provision in the final 
rule to allow a dental office that does not reasonably expect to place 
or remove dental amalgam to provide immediate treatment, such as where 
unplanned, unanticipated removal of the amalgam is necessary at that 
facility at that time, in the professional judgment of the dentist. 
EPA's intent is to exclude dental offices from the rule's requirements, 
other than a one-time report, for unplanned removals. In EPA's view, 
dental offices that remove amalgam at a frequency more often than five 
percent of its procedures are not likely engaging in only limited, 
unplanned removals. EPA estimates that on average, a single chair 
dental office would remove amalgam 183 times per year (DCN DA00467). An 
amalgam removal rate that represents less than five percent of this 
frequency consists of approximately nine removals per year, on average, 
respectively. However, because EPA does not have, nor did commenters 
provide, data on the frequency of such unplanned and unanticipated 
instances nationwide, the final rule does not include a specific 
definition of limited circumstances. Rather, EPA expects a dental 
office to carefully consider its operation in light of the information 
provided above and only certify accordingly to their Control Authority 
if it meets the situation EPA described.
3. Dental Discharger Reporting and On-Site Paperwork Compliance 
Requirements
    Dental dischargers subject to this rule must comply with a one-time 
reporting requirement specified in the final rule in lieu of the 
otherwise applicable reporting requirements in 40 CFR part 403. 
Submission of reports as specified in this rule satisfies the reporting 
requirements in 40 CFR parts 403 and 441. For dental offices that do 
not place or remove dental amalgam except in limited circumstances, 
dental offices must submit a One-Time Compliance Report that includes 
information on the facility and a certification statement that the 
dental discharger does not place dental amalgam and does not remove 
amalgam except in limited circumstances. For dental offices that place 
or remove dental amalgam, the One-Time Compliance Report must include 
information on the dental facility and its operations and a 
certification that the dental discharger meets the requirements of the 
applicable performance standard. Dentists that utilize a third party to 
maintain their separator must report that information in their One-Time 
Compliance Report. Dentists that do not utilize a third party to 
maintain the amalgam separator(s) must provide a description of the 
practices employed by the office to ensure proper operation and 
maintenance. EPA suggests dental offices consider use of signs 
displayed prominently in the office or electronic calendar alerts to 
remind staff of dates to perform and document monthly inspections, 
cartridge replacement, etc.
    If a dental practice changes ownership (which is a change in the 
responsible party, as defined in 40 CFR 403.12(l)), the new owner must 
submit a One-Time Compliance Report that contains the required 
information.
    The One-Time Compliance Report must be signed by (1) a responsible 
corporate officer if the dental office is a corporation; (2) a general 
partner or proprietor if the dental office is a partnership or sole 
proprietorship; or (3) a duly authorized representative of the 
responsible corporate officer, or general partner or proprietor. This 
does not preclude a third party from submitting the report on behalf of 
a dental office as long as the submission also includes a proper 
signature as described above.
    The final rule does not require electronic reporting nor does it 
prevent electronic reporting. EPA received several comments requesting 
that EPA develop an electronic compliance reporting system as a part of 
this final rule. These commenters generally advocated for electronic 
reporting due to the size of the industry and the proposed annual 
reporting requirement. During development of the final rule, EPA 
considered several variations of requirements for dental dischargers to 
report electronically (which would have necessitated an electronic 
system). Most commonly, electronic systems are preferable when reports 
must be submitted on a periodic basis. EPA ultimately decided not to 
specify electronic reporting in the final rule after it determined the 
final rule would only require a one-time compliance report from each 
affected dental discharger.
    Still, EPA recognizes that some Control Authorities may prefer to 
receive the one-time reports electronically or to provide affected

[[Page 27164]]

dental dischargers with the option to report electronically. EPA also 
recognizes that electronic submittal of required reports could increase 
the usefulness of the reports, is in keeping with current trends in 
compliance reporting, and could result in less burden on the regulated 
community and the Control Authorities. EPA may develop and make 
available, via its E-Enterprise portal, an electronic reporting system 
that Control Authorities could use to facilitate the receipt of reports 
from dental dischargers, if they choose to do so. At some future date, 
EPA could decide to revise this final rule to require electronic 
reporting. If it chose to do so, EPA would first propose the revisions 
and provide an opportunity for public review and comment.
    Finally, the final rule requires dental offices to document certain 
operation and maintenance requirements and maintain all records of 
compliance, as described in the regulation, and to make them available 
for inspection.
4. Control Authority Oversight/Reporting
    EPA proposed to amend selected parts of the General Pretreatment 
Regulations (40 CFR part 403) in order to simplify oversight 
requirements for the approximately 117,000 dental offices subject to 
the proposed rule. Specifically, EPA proposed to amend 40 CFR part 403 
to create a new classification of categorical industrial users 
specifically tailored to pretreatment standards for dental offices, 
dental industrial user (DIU). EPA proposed that as long as a dental 
office complied with the requirements for DIUs, that it would not be 
considered an SIU. Among other things, this would have reduced the 
General Pretreatment Regulation oversight requirements for Control 
Authorities, such as the requirement to issue a control mechanism and 
annual inspection and sampling.
    EPA received numerous comments related to the proposed change, 
particularly from the Control Authorities. These commenters largely 
supported the reduced oversight requirements in the proposal, but 
encouraged EPA to reduce them further so that dental offices would 
never be SIUs, primarily due to concerns over the associated burden 
given the large number of dental offices potentially subject to the 
rule. In addition, Control Authorities raised concerns that they would 
have to update state and local laws to take advantage of the proposed 
changes to part 403 that would reduce the oversight requirements. They 
also raised concerns about additional reporting requirements for the 
Control Authorities typically associated with CIUs, such as identifying 
CIUs in their annual pretreatment report to the Approval Authority.
    In response, EPA did not revise the General Pretreatment Standards 
to create the proposed DIU category and associated requirements. 
Rather, this rule establishes for the purposes of part 441, that dental 
dischargers are not SIUs or CIUs as defined in 40 CFR part 403 unless 
designated as such by the Control Authority. This regulatory structure 
achieves the same goal as the proposed revisions to the General 
Pretreatment Standards--simplification of oversight requirements--
without creating a need for updates to state and local laws. By 
establishing that dental dischargers are not SIUs or CIUs in the final 
rule, EPA eliminates the application of specific oversight and 
reporting requirements in 40 CFR part 403 such as permitting and annual 
inspections of dental dischargers for SIUs and CIUs unless the Control 
Authority chooses to apply these requirements to dental offices. This 
means that Control Authorities have discretion under the final rule to 
determine the appropriate manner of oversight, compliance assistance, 
and enforcement.\9\ Further, the final rule reduced reporting for 
dental offices (and associated oversight requirements by Control 
Authorities) in comparison to reporting requirements for other 
industries subject to categorical pretreatment standards, as it 
requires only a One-Time Compliance Report be submitted to the Control 
Authority. The One-Time Compliance Report requirements specific to 
dental dischargers are included in this rule rather than in the General 
Pretreatment regulations so that they may be implemented directly. In 
summary, for this final rule, the Control Authorities must receive the 
One-Time Compliance Reports from dental dischargers and retain that 
notification according to the standard records retention protocol 
contained in Sec.  403.12(o).
---------------------------------------------------------------------------

    \9\ Nothing stated in this section shall be construed so as to 
limit EPA's inspection and enforcement authority.
---------------------------------------------------------------------------

    Where EPA is the Control Authority, EPA expects to explore 
compliance monitoring approaches that support sector-wide compliance 
evaluations, to the extent practicable. States and POTWs that are the 
Control Authority may elect to use the same approach but are not 
required to do so. One approach may be periodic review and evaluation 
of nationwide data on releases of dental amalgam metals (e.g., 
mercury), relying on Discharge Monitoring Reports from POTWs, Annual 
Biosolids Reports from POTWs, emissions data from sludge incinerators, 
and supplemental data submitted to EPA under the Toxic Releases 
Inventory program. EPA may utilize an approach to compliance 
inspections that focuses on a statistically valid sample of the 
regulated community. EPA may then use the inspection findings from such 
an approach to identify common areas of noncompliance, which would 
inform decisions about needed outreach, compliance assistance, and 
training materials. EPA will work with state and local Control 
Authorities, the ADA and other partners to tailor oversight and 
outreach to the issues where such oversight and outreach is most likely 
to achieve compliance across the dental sector.
5. Interaction With Existing State and Local Mandatory Dental Amalgam 
Reduction Programs
    The final rule applies to both dental offices that are subject to 
existing mandatory state or local dental amalgam reduction programs and 
those that are not. Some proposal commenters, many of whom are in 
states and localities with existing programs, questioned the 
application of this rule to dentists already subject to state and local 
programs noting the duplicative requirements. While EPA found that many 
of the existing programs contained at least one attribute of this final 
rule (e.g. separators, reporting, BMPs, operation and maintenance), the 
majority did not contain all of the attributes. Generally, the 
additional requirements (and associated costs) of this final rule are 
incremental over existing mandatory state or local dental amalgam 
reduction requirements. For example, a dentist located in a state or 
locality that does not require one or both of the BMPs specified in 
this rule must implement both BMPs. While the requirements of this rule 
are incremental to existing state and local regulatory requirements, 
EPA finds they are necessary to achieve the intended environmental 
objectives of the rule. Applying categorical pretreatment standards to 
pollutant discharges from dental offices irrespective of existing 
discharge requirements is consistent with the general approach to 
pretreatment standards under the CWA in that it establishes uniform 
requirements that form the floor of performance for all dischargers in 
a regulated category.
    In addition, requiring all dental offices to meet the same 
requirements, regardless of the applicability of other

[[Page 27165]]

state or local requirements, avoids substantial implementation 
challenges and potential confusion associated with alternative 
approaches. EPA considered several approaches for accommodating 
dentists in states and localities with existing and local requirements. 
For example, EPA considered exempting dentists subject to equivalent 
state and local requirements from the scope of this rule. EPA rejected 
this approach, in part, due to the complexities and potential confusion 
associated with evaluating and communicating the equivalency of state 
and local requirements to this rule, particularly as they may change 
over time.
    The rule establishes clear requirements for all parties and 
compliance with the final rule is simple and straightforward for dental 
offices and the regulating authorities. It requires dental offices to 
install and operate a separator, to implement two BMPs, and to submit a 
One-time Compliance Report to the Control Authority. Thereafter, the 
dental office will be required to conduct ongoing operation and 
maintenance and maintain associated records. These activities can be 
facilitated by third parties such as dental office suppliers and 
amalgam separator manufacturers. EPA does not expect the federal 
requirements to conflict with existing state or local mandatory amalgam 
reduction requirements. Rather, EPA concludes this final rule imposes 
only incremental additional requirements (e.g., one-time compliance 
report) to their Control Authority, if any, on dental offices already 
subject to state or local amalgam reduction requirements. For Control 
Authorities, because EPA significantly reduced the oversight 
requirements associated with this rule, the incremental costs and 
burden to apply the final rule's requirements to dental facilities 
subject to some existing mandatory dental amalgam reduction 
requirements are minimal. The only incremental requirement associated 
with this rule is for the Control Authority to receive, review, and 
retain a One-time Compliance Report from dentists subject to this rule.
6. Variances
    The provision of this rule establishing that dental dischargers are 
not SIUs or CIUs unless designated as such by the Control Authority 
does not change the otherwise applicable variances and modifications 
provided by the statute. For example, EPA can develop pretreatment 
standards different from the otherwise applicable requirements for an 
individual existing discharger subject to categorical pretreatment 
standards if it is fundamentally different with respect to factors 
considered in establishing the standards applicable to the individual 
discharger. Such a modification is known as a ``fundamentally different 
factors'' (FDF) variance. See 40 CFR 403.13 and the preamble to the 
proposed rule (79 FR 63278-63279, October 22, 2014). FDF variances 
traditionally have been available to industrial users subject to 
categorical pretreatment standards. Whether or not a dental discharger 
is an SIU or CIU, it is subject to categorical pretreatment standards 
and therefore eligible to apply for an FDF variance.

E. Pollutants of Concern and Pass Through Analysis

    CWA section 301(b) directs EPA to eliminate the discharge of all 
pollutants where it is technologically available and economically 
achievable (after a consideration of the factors specified in section 
304(b) of the Act). The first step in such an analysis is typically to 
identify Pollutants of Concern (POCs)--or the pollutants potentially 
regulated in the effluent guideline. For this rule, EPA identifies the 
primary metals in dental amalgam as pollutants of concern: Mercury, 
silver, tin, copper, and zinc.
    Generally, in determining whether pollutants pass through a POTW 
when considering the establishment of categorical pretreatment 
standards, EPA compares the median percentage of the pollutant removed 
by POTWs achieving secondary treatment with the median percentage of 
the pollutant removed by facilities meeting BAT effluent limitations. 
EPA deems a pollutant to pass through a POTW when the percentage 
removed by POTWs is less than the percentage removed by direct 
dischargers complying with BPT/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. In the case of this 
final rulemaking, where EPA is only developing pretreatment standards, 
EPA compares the POTW removals with removals achieved by indirect 
dischargers using the 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). This well documented study presents data 
on the performance of 50 POTWs achieving secondary treatment in 
removing toxic pollutants. As part of the development of ELGs for the 
Centralized Waste Treatment (CWT) Industry promulgated in December 
2000, EPA developed and documented a methodology, including data 
editing criteria, to calculate POTW percent removals for various toxic 
pollutants from the data collected in the study. EPA provided the 
opportunity for public comment on the percent removal methodology and 
the resulting percent removals in the CWT proposal. EPA similarly used 
and presented this methodology and data in subsequent ELG proposals and 
final rules. Using its long-standing approach, for this final rule, EPA 
determined the median percent removal by POTWs achieving secondary 
treatment is 90.2 percent for total mercury, and 42.6 percent to 88.3 
percent for the other pollutants of concern.
    As described above, the 50 POTW Study measured pollutant reductions 
on the basis of total metals. Total metals include particulate 
(suspended) and dissolved (soluble) forms of the metal. As discussed 
above, while mercury is present in dental amalgam in both the 
particulate and dissolved form, the vast majority (>99.6 percent) is 
particulate. While EPA does not have information on the distribution of 
the other metals, EPA reasonably assumes the same distribution for the 
other metals. Because secondary treatment technologies are not designed 
to remove dissolved metals, EPA assumes dissolved metals are not 
removed by POTWs and that the percent reductions for POTWs represent 
particulate reductions.
    To determine the median percent removal of the pollutants of 
concern by amalgam separators, EPA collected information on the 
efficacy of existing separators. EPA excluded those separators that did 
not meet the 2008 ISO standards. At proposal, EPA determined the median 
percent removal of total mercury to be 99.0 percent, which is the 
reported removal when testing each of the amalgam separators marketed 
in the U.S. as conforming to the ISO standard (DCN DA00233). Commenters 
noted that existing data on the effectiveness of separators is measured 
as a percent reduction in mass, reflecting the dental amalgam 
particulates (rather than total mercury) collected by the device. EPA 
agrees the ISO standard evaluates particulates from dental amalgam 
rather than total mercury, and has adjusted its terminology 
accordingly. Based on updated information in the record, EPA determined 
the median percent removal of particulates by amalgam separators that 
meet the 2008 ISO standards is 99.3 percent. As such, because the 
median

[[Page 27166]]

percent removal of amalgam separators exceeds the median percent 
removal of well-operated POTWs employing secondary treatment for 
mercury and the other POCs, EPA determines that mercury and the other 
POCs pass through.
    In addition to comments relating to dissolved mercury, EPA received 
other comments and data pertaining to the proposed median percent 
removal of ISO compliant amalgam separators. Some commenters supported 
the percentage identified in the proposal, noting that certain states 
require the same level of performance, or identifying separators 
documented as achieving or exceeding that removal efficiency. Other 
commenters questioned EPA's use of the data collected when laboratories 
certify amalgam separators to meet the ISO standard. More specifically, 
they asserted that the 2008 ISO standard requires the removal 
efficiency of the amalgam separator to be at least 95 percent on a mass 
fraction basis and as such, the ISO standard is not a validated test 
for measuring higher efficiencies. These commenters offered no data to 
demonstrate that the reported removals in excess of 95 percent were 
inaccurate, nor did commenters provide other efficiency data for 
amalgam separators. As it represents the best data available for the 
final rule, EPA appropriately used the data as reported to estimate the 
efficacy of amalgam separators for these purposes. EPA notes that even 
if commenters correctly characterized the minimum percent removal 
efficiency of amalgam separators meeting the 2008 ISO standard as 95 
percent, this is a higher removal rate than the median percent removal 
by POTWs for all POCs. Therefore, while EPA based its analysis in the 
final rule on the percent removals as reported, under either case, EPA 
determines that mercury and the other POCs pass through.
    Other commenters stated the 50 POTW Study data were old, and that 
current POTW removals are higher than 90 percent. Some provided case 
studies, many of which reflected POTWs with advanced treatment 
capabilities rather than secondary treatment. In particular, the 
National Association of Clean Water Agencies (NACWA) submitted data 
from a nationwide voluntary survey of its members regarding mercury 
reductions at POTWs. Based on its analysis of the data collected in 
this survey, NACWA calculated a three-year average removal efficiency 
of 94 percent.\10\ EPA notes that even if EPA were to accept these data 
and analyses as presented by NACWA without further review, it would 
confirm EPA's conclusion that pass through of POCs occurs because this 
percentage is less than the median efficiency of 2008 ISO compliant 
amalgam separators of 99.3 percent.
---------------------------------------------------------------------------

    \10\ EPA notes that in conducting its pass through analysis, EPA 
calculates and compares median percent removals rather than average 
percent removals.
---------------------------------------------------------------------------

    EPA, however, gave full consideration to the NACWA survey and 
subjected the mercury influent and effluent data from the 41 POTWs from 
that survey to similar review and data editing criteria as influent and 
effluent data collected for the 50 POTW Study. In this way, EPA 
attempted to give the NACWA data full and equal consideration as the 
historical data from the 50 POTW Study. EPA created a database of the 
raw data in order to conduct its analysis. (DCN DA00463). When EPA 
calculated the median percent removal of the non-edited raw data as 
submitted by NACWA, the median plant performance was 93.8 percent, with 
a range of 57.2 percent to 99.1 percent. In reviewing the data used in 
that calculation, EPA identified numerous data points that would not 
satisfy the data editing criteria applied in the 50 POTW Study, 
including data points representing combined data rather than raw data, 
order of magnitude outlier concentrations, and incorrectly reported 
units of measure. Other discrepancies between data and analyses from 
the 50 POTW Study and NACWA survey include upward bias of using data 
from voluntary respondents, representing non-detect influent 
concentrations as zero,\11\ inclusion of several POTWs using BNR 
(biological nutrient removal) and other advanced treatment expected to 
perform better than secondary treatment, overrepresentation of areas 
with existing dental amalgam reduction programs, and 
underrepresentation of certain geographical areas. Sensitivity analyses 
around these data are found in the record. (DCN DA00464).
---------------------------------------------------------------------------

    \11\ EPA generally handles non-detect values in the reported 
data by replacing them with a value of one-half of the detection 
level for the observation that yielded the non-detect. This 
methodology is standard procedure for the ELG program as well as 
Clean Water Act assessment and permitting, Safe Drinking Water Act 
monitoring, and Resource Conservation and Recovery Act and Superfund 
programs; and this approach is consistent with previous ELGs.
---------------------------------------------------------------------------

    Consequently, for all of the reasons identified above, for this 
final rule, EPA finds that data from the 50 POTW Study continues to 
represent the best data available to determine the percent removed 
nationwide by well operated POTWs employing secondary treatment. Based 
on the information in its record including full consideration of 
comments, EPA appropriately concludes that the median percent removal 
of amalgam separators is higher than the median percent removal of 
POTWs for mercury and the other pollutants of concern. As such, EPA 
concludes mercury and the other POCs pass through.

VII. Technology Costs

    This section summarizes EPA's approach for estimating incremental 
compliance costs to implement changes associated with this rule, while 
the TEDD provides detailed information on the methodology. The costing 
methodology for the final rule is the same as that described in the 
proposal (79 FR 63269; October 22, 2014); however, EPA updated some of 
the specific data elements. EPA estimated compliance costs using data 
collected through EPA's Health Services Industry Detailed Study (August 
2008) [EPA-821-R-08-014], a review of the literature, information 
supplied by vendors, and data submitted with comments on the proposed 
rule. In estimating the total cost of the regulatory options, EPA 
estimated costs for the following components: Capital costs and other 
one-time costs; installation costs; annual operation and maintenance 
costs; and recordkeeping and reporting costs. EPA incorporated 
information received in comments pertaining to specific elements of the 
cost analysis, resulting in an increase in the initial installation 
cost and a minor increase in the average costs of dental amalgam 
separators that meet the 2008 ISO standard. In addition, EPA adjusted 
the reporting and recordkeeping costs to reflect the final rule 
requirements.
    The cost estimates reflect the incremental costs attributed only to 
this final rule. For example, offices required by a state or local 
program to have an amalgam separator compliant with the 2008 ISO 11143 
standard will not incur costs to retrofit a separator as a result of 
this rule. Others may certify that they do not place or remove amalgam. 
Such offices may still have costs under this final rule such as those 
associated with the one-time reporting requirement to certify that they 
do not place or remove amalgam. EPA's cost methodology assumes dental 
offices would use the required BMPs in combination with 2008 ISO 11143 
amalgam separators to comply with the rule. All final cost estimates 
are expressed in terms of 2016 dollars.
    EPA used a model office approach to calculate costs of this rule. 
Under this approach, EPA developed a series of model dental offices 
that exhibited the

[[Page 27167]]

typical characteristics of the regulated dental offices, and then 
calculated costs for each type of model office. EPA then determined how 
many of each model office accurately represented the full universe of 
affected offices. While this part of the methodology remains unchanged 
from the proposal, EPA updated the number of offices in each model to 
reflect current existing state and local programs and, in the case of 
very large offices, to reflect new data obtained in public comments on 
the number of clinics and schools subject to this rule.

A. Costs for Model Dental Offices

    EPA used the model approach to estimate costs for offices that 
place or remove amalgam for this final rule. EPA developed compliance 
costs for seven models, where each model is 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, 7-14 chairs (average of 
10 chairs), and 15 chairs. EPA developed the 15 chairs model 
specifically to represent large institutional offices. This is 
discussed separately below in Section VII.B. EPA developed two sets of 
costs for each model: One for offices that do not use an amalgam 
separator and one for offices that do use an amalgam separator.
    For those offices that currently do not use an amalgam separator, 
EPA estimated one-time and annual costs. One-time costs include 
purchase of the separator and installation, and preparation of the One-
time Compliance Report. Annual costs, for those offices that do use an 
amalgam separator, include visual inspection, replacement of the 
amalgam-retaining unit (e.g., cartridge or filter), separator 
maintenance and repair, recycling (preparation and services), and 
recordkeeping. Recordkeeping costs include documentation of inspection, 
separator maintenance and repair, and recycling (preparation and 
services). EPA also estimated periodic recordkeeping costs associated 
with repairs and One-Time Compliance Reports for new offices, which are 
included in the total of recordkeeping costs. Annual costs also include 
a cost offset, reflecting a cost savings as a result of changes that 
occur in the dental office due to the final rule requirements. More 
specifically, EPA received data in comments that an amalgam separator 
would protect the vacuum system filter and impeller blade from small 
particles, resulting in less frequent replacement and servicing of 
these elements when an amalgam separator has been installed. In the 
final rule cost analysis, EPA accordingly reduced the overall operation 
and maintenance costs for those dental offices that do not already have 
an amalgam separator. This cost offset reflects the reduced cost to 
dental offices of servicing the vacuum system filter and impeller 
blade. A summary of costs for dental offices that do not currently use 
amalgam separators may be found in Tables VII-1 and VII-2, see the TEDD 
for more details.
---------------------------------------------------------------------------

    \12\ 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.
    \13\ 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 VII-1--Summary of One Time Model Facility Costs ($2016) for Dental Offices That Do Not Currently Use
                                               Amalgam Separators
----------------------------------------------------------------------------------------------------------------
                                                    Number of chairs in the model dental office
                                 -------------------------------------------------------------------------------
          Cost element                              3, 4, or 5
                                      1 or 2           \12\              6            7 to 14           15
----------------------------------------------------------------------------------------------------------------
Separator Purchase..............            $437            $697          $1,058          $1,291          $2,424
Installation....................             235             276             276             358             942
One-Time Compliance Report......              23              23              23              23              23
----------------------------------------------------------------------------------------------------------------


Table VII-2--Summary of Annual Model Facility Costs ($2016) for Dental Offices That Do Not Currently Use Amalgam
                                                   Separators
----------------------------------------------------------------------------------------------------------------
                                                    Number of chairs in the model dental office
                                 -------------------------------------------------------------------------------
          Cost element                              3, 4, or 5
                                      1 or 2           \13\              6            7 to 14           15
----------------------------------------------------------------------------------------------------------------
Replacement Parts...............            $275            $386            $559            $732          $1,078
Separator Maintenance...........             115             115             115             115             115
Maintenance Cost Off-set........             -75             -75             -75             -75             -75
Recycling.......................              91              91              91              91              91
Visual Inspection...............              18              18              18              18              18
Recordkeeping...................              62              62              62              62              62
----------------------------------------------------------------------------------------------------------------

    For those offices that already have an amalgam separator, EPA 
calculated costs for certain incremental annual costs associated with 
the amalgam separator required for this rule. Because these offices 
have separators, EPA only included a one-time cost for a One-Time 
Compliance Report ($23/office). Annual costs for such offices include 
visual inspection, replacement of the amalgam-retaining unit, separator 
maintenance and repair, recycling (preparation and services), and 
recordkeeping. Because these offices have amalgam separators in place, 
they are already incurring the majority of these costs irrespective of 
this final rule. As such, for those components (e.g., replacement of 
the cartridge and operation and maintenance), EPA calculated their 
incremental costs as a portion (percentage) of annual costs for dental 
offices without technology in place. Recordkeeping costs include 
documentation of inspection, separator maintenance and repair, and 
recycling (preparation and services). EPA also estimated periodic 
recordkeeping costs associated with repairs and One-Time Compliance 
Reports for new offices, which are included in the total of 
recordkeeping costs. EPA did not include the cost offset in this model, 
as

[[Page 27168]]

described above. A summary of these annual costs may be found in Table 
VII-3, see the TEDD for more details.

    Table VII-3--Summary of Annual Model Facility Costs ($2016) for Dental Offices That Currently Use Amalgam
                                                   Separators
----------------------------------------------------------------------------------------------------------------
                                                    Number of chairs in the model dental office
                                 -------------------------------------------------------------------------------
          Cost element                              3, 4, or 5
                                      1 or 2           \14\              6            7 to 14           15
----------------------------------------------------------------------------------------------------------------
Replacement Parts...............            $138            $193            $280            $366            $539
Separator Maintenance...........              58              58              58              58              58
Recycling.......................              45              45              45              45              45
Inspection......................              18              18              18              18              18
Recordkeeping...................              62              62              62              62              62
----------------------------------------------------------------------------------------------------------------

    In assessing the long term costs of rule compliance for these model 
offices (those with and without existing separators), EPA assumed that 
amalgam separators would have a service life of 10 years, at which time 
the amalgam separators would need to be replaced (DCN DA00163). 
Furthermore, the cost model assumes all dental amalgam separators 
installed prior to this rule would need to be replaced within 10 years 
of the effective date of this rule. Therefore, for the purposes of 
estimating compliance costs, EPA assumed that all offices subject to 
this rule would incur the cost of installing a new amalgam separator 10 
years after the effective date of this rule. However, because various 
modifications needed by the office for initial amalgam separator 
installation would have already been completed, EPA has projected the 
installation costs for amalgam separators would be one-half of the cost 
of the original installation. EPA assumed that all dental offices would 
continue to incur recurring expenses such as O&M beyond year 10 in the 
same way as described for the initial installation. To the extent 
dental offices either close or certify they no longer remove or place 
amalgam, the costs are likely overstated.
---------------------------------------------------------------------------

    \14\ 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.
---------------------------------------------------------------------------

    EPA projects that there will be no incremental costs associated 
with the required BMPs because (1) costs for non-oxidizing, pH neutral 
line cleaners are roughly equivalent to other line cleaners; and (2) 
dental offices will not incur additional costs by changing the location 
for flushing waste amalgam.

B. Costs for Larger Institutional Dental Offices

    Institutional dental offices (e.g., military clinics or dental 
schools) have a larger number of chairs than the typical dental office. 
For these institutional dental offices, EPA developed a costing 
methodology based on the methodology for offices described above. For 
purposes of costs, consistent with the proposal, EPA assumed the 
average institutional office has 15 chairs.\15\ As shown in Chapter 9 
of the TEDD, EPA has cost information for five amalgam separators that 
have a maximum design ranging from 17-22 chairs. EPA also has costs for 
a unit that can be custom sized for chair sizes of 16 or greater. EPA 
used the information for these six separators to estimate costs for 
institutional facilities. See DCN DA00454. These costs are likely 
overstated as they do not reflect opportunities the largest offices may 
have to share costs,\16\ and they do not assume any economies of scale. 
In addition, it is possible that the largest offices have multiple 
plumbing lines, allowing the installation of dental amalgam separators 
(or equivalent devices) only for those chairs used for placing or 
removing amalgam. See the proposed preamble and the TEDD for additional 
details on the costing methodology for institutional offices.
---------------------------------------------------------------------------

    \15\ This represents the number of chairs that can be used for 
the placement and/or removal of amalgam at a particular location. 
EPA received comments for institutional facilities indicating they 
had 7, 15, or 25 chairs. EPA selected the median of these values for 
purposes of this analysis.
    \16\ 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.
---------------------------------------------------------------------------

VIII. Pollutant Loads

    As was the case for costing, EPA does not have office-specific 
discharge data for the approximately 117,000 dental offices potentially 
subject to this rule. Instead, EPA modeled the baseline, pre-rule 
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.\17\ The 
technology basis used to estimate the compliance costs of this rule 
includes 2008 ISO 11143 amalgam separators available on the market 
today, and certain BMPs. The median performance of these separators is 
99.3 percent. EPA assumes all offices have chair-side traps or a 
combination of chair-side traps and vacuum filters that result in 68 
percent and 78 percent collection of dental amalgam, respectively (DCN 
DA00163). After accounting for mercury reductions achieved through 
existing chair-side traps and vacuum pump filters, EPA's analysis 
reduces remaining mercury loads to reflect the combination of chair-
side traps, vacuum filters, and amalgam separators. Therefore, EPA 
assumed a post-rule reduction in mercury loads to POTWs based on a 99.8 
percent removal rate. This is the same approach and data that EPA 
presented in the proposal (79 FR 623275; October 22, 2014).
---------------------------------------------------------------------------

    \17\ Because this approach is based on the number of dentists, 
it includes those dentists both at offices and institutional 
offices.
---------------------------------------------------------------------------

    Amalgam is comprised of roughly 49 percent mercury, 35 percent 
silver, 9 percent tin, 6 percent copper and 1 percent zinc (DCN 
DA00131). As explained earlier in Section VI, EPA concludes that the 
technology basis would be equally effective in reducing discharges of 
silver, tin, copper, and zinc as it is in reducing mercury. EPA 
therefore applied the same approach to estimating reductions of other 
metals found in dental amalgam. In other words, EPA assumes chair-side 
traps and the combination of chair-side traps and vacuum filters will 
result in 68 percent and 78 percent collection of these metals, 
respectively. Remaining amalgam metals are further reduced by an 
amalgam separator, as discussed above.

[[Page 27169]]

A. National Estimate of Annual Pollutant Reductions to POTWs Associated 
With This Rule \18\

1. Mercury
    EPA estimates the approximately 55,000 offices that install 
separators would obtain 99.3 percent removal of particulate mercury 
through the use of amalgam separators (median removal efficiency of 
amalgam separators; see Chapter 7 of the TEDD). This would result in 
reduction of particulate mercury discharges to POTWs by approximately 
5.1 tons. Amalgam separators are not effective in removing dissolved 
mercury. However, dissolved mercury accounts for much less than 1 
percent of the total mercury, so the form of mercury removed from 
discharges to POTWs is assumed to consist of particulate (solids) only.
---------------------------------------------------------------------------

    \18\ EPA's approach is not dynamic, as it does not account for 
declining use of dental amalgam. See additional discussion in V.B.
---------------------------------------------------------------------------

2. Other Metals
    As explained earlier in Section VI, EPA concludes that the 
technology basis for this final rule would be equally effective in 
reducing discharges of silver, tin, copper, and zinc as it is in 
reducing mercury. Accordingly, EPA estimates a reduction of these metal 
discharges to POTWs of approximately 5.3 tons.
3. Total Reductions
    EPA estimates this final rule would annually reduce particulate 
mercury and other metal particulate discharges by a total of 10.3 tons.

B. National Estimate of Annual Pollutant Reductions to Surface Waters 
Associated With This Rule

    In order to evaluate final discharges of mercury (and other metals) 
to waters of the U.S. by the POTW, EPA used its 50 POTW Study to 
calculate POTW removals of each metal. As explained above, at baseline 
and prior to implementation of this rule, EPA estimates 5.1 tons of 
dental mercury particulates are collectively discharged annually to 
POTWs. Based on the 50 POTW Study, EPA estimates POTWs remove 90.2 
percent of dental mercury from the wastewater. Thus, POTWs collectively 
discharge 1,003 pounds of mercury from dental amalgam to surface waters 
annually. Under this final rule, 99.8 percent of mercury particulates 
currently discharged annually to POTWs will be removed prior to the 
POTW. The POTWs then further remove 90.2 percent of the remaining 
particulate mercury from the wastewater. This reduces the total amount 
of dental mercury particulates discharged from POTWs nationwide to 
surface water to 11 pounds of mercury annually. In other words, 
discharges of dental mercury to waters of the U.S. from POTWs are 
expected to be reduced by 992 pounds per year.\19\ Similarly, EPA's 50 
POTW Study data shows 42.6 percent to 88.3 percent of other metals in 
the wastewater are removed by POTWs. As explained above, EPA estimates 
5.3 tons of other metals are also collectively discharged annually from 
dental offices to POTWs. Thus, POTWs collectively discharge 
approximately 2,178 pounds of other dental metals to surface waters 
annually. Following compliance with this rule, the total amount of 
other dental metal discharges from POTWs nationwide to surface waters 
will be approximately 24 pounds or a reduction of 2,153. See Chapter 11 
of the TEDD for more details.
---------------------------------------------------------------------------

    \19\ Dissolved mercury accounts for a portion of surface water 
discharges, because amalgam separators do not remove dissolved 
mercury.
---------------------------------------------------------------------------

IX. Economic Impact Analysis

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

A. Social Cost Estimates

    As described earlier in Section VI of this preamble, EPA based the 
technology standard for the final rule on a widely available 
technology, amalgam separators, and employment of readily available 
BMPs. Section VII provides a detailed explanation of how EPA estimated 
compliance costs for model dental offices. As applicable, EPA 
annualized the capital costs over a 20-year period at a discount rate 
of 7 percent and 3 percent \20\ and summed these costs with the O&M and 
reporting/recordkeeping costs to determine an annual compliance cost 
estimate for each model facility. See the TEDD for more details.
---------------------------------------------------------------------------

    \20\ See the TEDD for the reported analyses using both a 7 
percent and 3 percent discount rate.
---------------------------------------------------------------------------

    In order to develop a national estimate of social costs \21\ based 
on these model offices, EPA estimated the number of dental offices 
represented by each model office. EPA categorized dental offices based 
on the number of chairs in each office.\22\ The 2012 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, estimate distribution of dentist 
offices by number of chairs (DCN DA00141 and DCN DA00149). EPA used 
these two data sources to correlate the number of chairs per office to 
the revenue range of dental offices. EPA averaged the correlation of 
these two studies to estimate the number of dental offices by the 
number of chairs. The results are reported in table IX-1:
---------------------------------------------------------------------------

    \21\ 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.
    \22\ Amalgam separators are typically designed based on the 
number of chairs.

                            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......................................................          16,606          12,976          14,791
3 chairs........................................................          57,841          33,738          31,329
4 chairs........................................................  ..............          38,928          33,924
5 chairs........................................................          35,638          19,032          18,425
6 chairs........................................................  ..............           7,786          12,802
7+ chairs.......................................................          23,136          20,762          21,949
                                                                 -----------------------------------------------

[[Page 27170]]

 
    Total.......................................................         133,221         133,221         133,221
----------------------------------------------------------------------------------------------------------------

    To estimate nationwide social costs, EPA multiplied the estimated 
total annualized costs of rule compliance for each model office 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). In EPA's analysis, for dental offices that do not place or 
remove amalgam, EPA assigned them costs for a baseline-compliance 
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 offices by 
multiplying the compliance cost for its model institutional offices 
(15-chair model) by the number of estimated institutional offices 
indicated in Section V. Lastly, EPA estimated costs for Control 
Authorities to administer the final rule. Details of this cost analysis 
can be found in the TEDD. See Table IX-2 for EPA's estimate of total 
nationwide annualized social costs for this final rule using a 3 
percent discount rate.\23\
---------------------------------------------------------------------------

    \23\ As a point of clarification, social costs equal the sum of 
compliance costs and administrative costs. Also, EPA used a 3 
percent discount rate for the social costs analysis.

      Table IX-2--Total Annualized Social Costs by Number of Chairs
                       [Millions of 2016 dollars]
------------------------------------------------------------------------
                                             Total annualized costs by
                                                  chair size \1\
            Number of chairs             -------------------------------
                                             Colorado
                                              survey        ADA survey
------------------------------------------------------------------------
1-2 chairs..............................            $4.2            $5.4
3 chairs................................            13.6            23.3
4 chairs................................            15.7  ..............
5 chairs................................             7.7            16.4
6 chairs................................             4.0  ..............
7-14 chairs.............................            13.1            14.6
15 chairs...............................             0.3             0.3
Cost to Control Authorities.............             0.8             0.8
                                         -------------------------------
    Total Annualized Social Costs.......            59.4            60.8
------------------------------------------------------------------------
\1\ These costs reflect estimated costs discounted to the year of
  promulgation. 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 percent
  discount rate was used for the analysis reported in this table; see
  the TEDD for the analysis reported with a 7% discount rate.

B. Economic Impact

    EPA devised a set of tests for analyzing economic achievability. As 
is often EPA's practice, the Agency conducted a cost-to-revenue 
analysis to examine the relationship between the costs of the rule to 
current (or pre-rule) dental office revenues as a screening analysis. 
In addition, EPA chose to examine the financial impacts of the rule 
using two measures that utilize the data EPA has on dental office 
baseline assets and estimated replacement capital costs: (1) Ratio of 
the Final Rule's Capital Costs to Total Dental Office Capital Assets 
and (2) Ratio of the Final Rule's Capital Costs to Annual Dental Office 
Capital Replacement Costs.
    EPA did not conduct a traditional closure analysis for this final 
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, and 
such accounting measures are difficult to implement for businesses that 
are organized as sole proprietorships or partnerships, as typically is 
the case in the dental industry. EPA considered whether it should 
exclude these offices from the analyses, which is described further in 
EPA's proposal (79 FR 63272; October 22, 2014). Because EPA did not 
receive any comments to the contrary, EPA used the same assumptions for 
this final rule as it did at proposal with regard to low-revenue 
offices. EPA concluded that offices making less than $25,400 were 
baseline closures as traditionally accounted for in cost and economic 
impact analysis for effluent guidelines rulemakings. Using the Economic 
Census, EPA estimated that to be approximately 531 offices. Still, 
because 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. For each of the three analyses 
conducted below, EPA used the same methodology for the final rule's 
impact analysis as described in the proposal because EPA did not 
receive any comments to suggest a different approach for each impact 
analysis. Lastly, EPA used a 7 percent discount rate for the costs used 
in these three analyses described below. See the proposed rule for 
further description of the analyses below (79 FR 63272; October 22, 
2014).

[[Page 27171]]

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 
when looking at impacts to small businesses 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. The 
cost-to-revenue analysis compares the total annualized compliance cost 
of each regulatory option with the revenue of the entities.
    EPA estimated the occurrence of annualized compliance costs 
exceeding the 1 percent and 3 percent of revenue thresholds for the 
final rule twice: (1) Excluding dental offices that could represent 
baseline closures (excluding baseline set-aside offices), and (2) 
including all offices in the analysis (including baseline set-aside 
offices).
    Table IX-3 summarizes the results from this analysis. As shown 
there, under either scenario, over 99 percent of dental offices subject 
to this rule would incur annualized compliance costs of less than 1 
percent of revenue. With baseline set-asides excluded from the 
analysis, 808 offices (0.7 percent of offices using dental amalgam and 
exceeding the set-aside revenue threshold) are estimated to incur costs 
exceeding 1 percent of revenue; no offices are estimated to incur costs 
exceeding 3 percent of revenue. With baseline set-asides included in 
the analysis, 1,217 offices (1 percent of offices using dental amalgam) 
are estimated to incur costs exceeding 1 percent of revenue; 174 
offices (0.1 percent of offices using dental amalgam) are estimated to 
incur costs exceeding 3 percent of revenue.

                               Table IX-3--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......................          12,914             808             6.3               0             0.0
3 chairs........................          27,353               0             0.0               0             0.0
4 chairs........................          29,619               0             0.0               0             0.0
5 chairs........................          16,087               0             0.0               0             0.0
6 chairs........................          11,177               0             0.0               0             0.0
7-14 chairs.....................          19,163               0             0.0               0             0.0
                                 -------------------------------------------------------------------------------
    Total.......................         116,313             808             0.7               0             0.0
----------------------------------------------------------------------------------------------------------------
                                Including Baseline Set-Aside Offices in Analysis
----------------------------------------------------------------------------------------------------------------
1-2 chairs......................          12,914           1,217             9.4             174             1.4
3 chairs........................          27,353               0             0.0               0             0.0
4 chairs........................          29,619               0             0.0               0             0.0
5 chairs........................          16,087               0             0.0               0             0.0
6 chairs........................          11,177               0             0.0               0             0.0
7-14 chairs.....................          19,163               0             0.0               0             0.0
                                 -------------------------------------------------------------------------------
    Total.......................         116,313           1,217             1.0             174             0.1
----------------------------------------------------------------------------------------------------------------

2. Ratio of the 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 final rule. A high ratio may still 
allow costs to be financed but could imply a need to change capital 
planning and budgeting.
    Table IX-4 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 0.4 
percent to 0.7 percent for the no technology in-place case and zero 
percent 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 0.4 percent to 0.7 
percent for the no technology in-place case and 0 percent for the 
technology in-place case.

          Table IX-4--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 Offices from Analysis
----------------------------------------------------------------------------------------------------------------
1-2 chairs......................................             0.1             0.0             2.4             1.2
3 chairs........................................             0.0             0.0             0.9             0.5
4 chairs........................................             0.0             0.0             0.6             0.4
5 chairs........................................             0.0             0.0             0.3             0.2
6 chairs........................................             0.0             0.0             0.3             0.2
7-14 chairs.....................................             0.0             0.0             0.2             0.1

[[Page 27172]]

 
Weighted Average................................             0.0             0.0             0.7             0.4
----------------------------------------------------------------------------------------------------------------
                                Including Baseline Set-Aside Offices in Analysis
----------------------------------------------------------------------------------------------------------------
1-2 chairs......................................             0.1             0.0             3.0             1.5
3 chairs........................................             0.0             0.0             0.9             0.5
4 chairs........................................             0.0             0.0             0.6             0.4
5 chairs........................................             0.0             0.0             0.3             0.2
6 chairs........................................             0.0             0.0             0.3             0.2
7-14 chairs.....................................             0.0             0.0             0.2             0.1
Weighted Average................................             0.0             0.0             0.7             0.4
----------------------------------------------------------------------------------------------------------------
\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 final rule compliance costs, as
  described in Section IX above, were assigned to each number-of-chairs category as the numerator for the ratio.

3. Comparison of the 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 rule to the estimated capital 
replacement costs for a dental office business (e.g., computer systems, 
chairs, x-ray machines, etc.) across all chair sizes. 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 final rule. A high ratio may still allow costs to be 
financed but could imply a need to change capital planning and 
budgeting. As expected, the results for this ratio are higher than the 
previous ratio in the test above, given that EPA expects replacement 
costs would be smaller than total capital assets. EPA performed this 
test because this ratio is based on a different data source, and so it 
provides an independent check that abstracts from the limitations of 
the data used in the test above. The resulting values for the final 
rule range from 2.0 percent to 2.8 percent, with a weighted average of 
2.4 percent across all chair size ranges.

  Table IX-5--Initial Spending as Percentage of Estimated Annual Dental
                  Office Capital Replacement Costs \1\
------------------------------------------------------------------------
                       Number of chairs                         Percent
------------------------------------------------------------------------
1-2 chairs...................................................        2.7
3 chairs.....................................................        2.8
4 chairs.....................................................        2.3
5 chairs.....................................................        2.0
6 chairs.....................................................        2.3
7 chairs.....................................................        2.5
8 chairs.....................................................        2.3
9 chairs.....................................................        2.1
Weighted Average.............................................        2.4
------------------------------------------------------------------------
\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. EPA assigned total final rule
  compliance costs, as described above in Section IX, to each number-of-
  chairs as the numerator for the ratio.

C. Economic Achievability

    The analyses performed above inform the potential economic impact 
of this final rule on the dental office sector. In the cost-to-revenue 
analysis, EPA found that no more than 0.1 percent of offices, mostly in 
the lower revenue ranges, would potentially incur costs in excess of 3 
percent of revenue. The two financial ratios reported in Tables IX-3 
and IX-4 show that the final rule will not cause dental offices to 
encounter difficulty in financing initial spending on capital costs of 
the final rule. Based on the combined results of the three analyses and 
that EPA had no data since proposal to suggest otherwise, EPA 
determined that the final rule is economically achievable. Regarding 
large offices, EPA notes that, due to a lack of data, the economic 
impact analyses did not include large institutional offices. EPA did 
not receive comments indicating large offices would be impacted more or 
less than other dental offices subject to this rule. Given the results 
of the economic analysis performed on a range of office sizes 
indicating that the rule is economically achievable, EPA finds the rule 
would similarly be achievable for large institutional offices.
    EPA determined that the final pretreatment standard for new sources 
will not be 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 
offices as described in Section VII) comprised 0.2 percent to 0.3 
percent of the cost of starting a dental practice as shown in Table IX-
6 and, therefore, does not pose a barrier to entry.

  Table IX-6--Initial Spending as Percentage of Estimated Dental Office
                             Start-Up Costs
------------------------------------------------------------------------
                       Number of chairs                         Percent
------------------------------------------------------------------------
1-2 chairs...................................................        0.3
3 chairs.....................................................        0.3
4 chairs.....................................................        0.3
5 chairs.....................................................        0.2
6 chairs.....................................................        0.3
7 chairs.....................................................        0.3
8 chairs.....................................................        0.3
9 chairs.....................................................        0.3
Weighted Average.............................................        0.3
------------------------------------------------------------------------

X. Cost-Effectiveness Analysis

    EPA often uses cost-effectiveness analysis in the development and 
revision of ELGs to evaluate the relative efficiency of alternative 
regulatory options in removing toxic pollutants from effluent 
discharges to our nation's waters. Although not required by the CWA, 
and not a determining factor for establishing PSES or PSNS, cost-
effectiveness analysis can be a useful

[[Page 27173]]

tool for describing regulatory options that address toxic pollutants.
    EPA defines the cost-effectiveness of a regulatory option as the 
incremental annual cost (in 1981 constant dollars to facilitate 
comparison to ELGs for other industrial categories promulgated over 
different years) per incremental toxic-weighted pollutant removals for 
that option. For more information about the methodology, data, and 
results, see Chapter 12 of the TEDD. EPA determines toxic-weighted 
pollutant removals for a particular pollutant by multiplying the number 
of pounds of a pollutant removed by an option by a toxic weighting 
factor (TWF). The toxic weighting factor for each pollutant measures 
its toxicity relative to copper,\24\ with more toxic pollutants having 
higher toxic weights. The use of toxic weights allows EPA to express 
the removals of different pollutants on a constant toxicity basis as 
toxic-pound- equivalents (lb-eq). In the case of indirect dischargers, 
the removal also accounts for the effectiveness of treatment at POTWs 
and reflects the toxic-weighted pounds after POTW treatment. The TWFs 
for the pollutants of concern are shown in Table X-1.
---------------------------------------------------------------------------

    \24\ When EPA first developed TWFs in 1981, it chose the copper 
freshwater chronic aquatic life criterion of 5.6 [mu]g/L as the 
benchmark scaling factor for deriving TWFs because copper was a 
common and well-studied toxic chemical in industrial waste streams. 
Consequently, the basic equation for deriving the TWF for any 
chemical is: TWF = 5.6 [mu]g/L/Aquatic Life Value ([mu]g/L) + 5.6 
[mu]g/L/Human Health Value ([mu]g/L). The chronic freshwater aquatic 
life criterion for copper, however, has been revised three times 
since it was first published in 1980 due to advances in the 
scientific understanding of its toxic effects. Thus, when 
calculating the TWF for copper, EPA normalizes the 1998 chronic 
freshwater aquatic life copper criterion of 9.0 [mu]g/L to the 
original 1980 copper criterion of 5.6 [mu]g/L by dividing 5.6 [mu]g/
L by 9.0 [mu]g/L and adding the quotient to 5.6 [mu]g/L divided by 
the copper human health value of 4444 [mu]g/L, which results in a 
copper TWF of 0.623.

   Table X-1--Toxic Weighting Factors for Pollutants in Dental Amalgam
------------------------------------------------------------------------
 
------------------------------------------------------------------------
Mercury.................................................             110
Silver..................................................           16.47
Tin.....................................................           0.301
Copper..................................................           0.623
Zinc....................................................           0.047
------------------------------------------------------------------------

    The costs used in the cost-effectiveness analyses are the estimated 
annual pre-tax costs described in Section IX, restated in 1981 dollars 
as a convention to allow comparisons with the reported cost 
effectiveness of other effluent guidelines. Collectively, the final 
PSES requirements have a cost-effectiveness ratio of $190-$195/lb-
equivalent as shown in Table X-2 below. This cost-effectiveness ratio 
falls within the range of cost-effectiveness ratios for PSES 
requirements in other industries. A review of approximately 25 of the 
most recently promulgated or revised categorical pretreatment standards 
shows PSES cost-effectiveness ranges from less than $1/lb-equivalent 
(Inorganic Chemicals) to $380/lb-equivalent (Transportation Equipment 
Cleaning) in 1981 dollars.

                                   Table X-2--PSES Cost Effectiveness Analysis
----------------------------------------------------------------------------------------------------------------
                                                                   Pre-tax total
                                                                    annualized    Removals  (lbs-  Average cost
                          Final option                             costs  ($1981        eq)        effectiveness
                                                                        M)
----------------------------------------------------------------------------------------------------------------
Colorado Survey.................................................           $23.5         123,552            $190
ADA National Survey.............................................            24.1         123,552             195
----------------------------------------------------------------------------------------------------------------

XI. Environmental Assessment

A. Environmental Impacts

    EPA conducted a literature review concerning potential 
environmental impacts associated with mercury in dental amalgam 
discharged to surface water by POTWs (DCN DA00148). As discussed above, 
studies indicate that dental offices are the largest source of mercury 
entering POTWs. The total annual baseline discharge of dental mercury 
to POTWs is approximately 10,239 pounds (5.1 tons): 10,198 pounds are 
in the form of solid particles (99.6 percent) and 41 pounds (0.4 
percent) are dissolved in the wastewater (DCN DA00018). Through POTW 
treatment, approximately 90 percent of dental mercury is removed from 
the wastewater and transferred to sewage sludge. The 10 percent of 
dental mercury not removed by POTW treatment is discharged to surface 
water. EPA estimates that POTWs annually discharge approximately 1,003 
pounds of dental mercury nationwide.
    The CWA regulations known as Standards for Use and Disposal of 
Sewage Sludge, 40 CFR part 503, control the land application, surface 
disposal, and incineration of sewage sludge generated by POTWs. Of the 
11.2 billion dry pounds of sewage sludge generated annually, about 60 
percent, or 6.7 billion pounds, are treated to produce biosolids for 
beneficial use as a soil amendment and applied to about 0.1 percent of 
agricultural lands in the United States (DCN DA00257). Approximately 
5,500 pounds per year of dental mercury are contained in land- applied 
biosolids.
    Approximately 18 percent, or 2 billion pounds, of the sewage sludge 
generated annually by POTWs are surface disposed in sewage sludge mono-
fills or municipal landfills. Approximately 1,700 pounds per year of 
dental mercury are contained in surface disposed sewage sludge. 
Pollutant limits and monitoring requirements for surface disposed 
sewage sludge mono-fills are set by 40 CFR part 503 and by 40 CFR part 
258 for municipal landfills. There may be additional state or local 
regulations that are more stringent than the federal biosolids 
regulations.
    The remaining 22 percent, or 2.5 billion pounds, of sewage sludge 
generated annually by POTWs is disposed of through incineration. 
Approximately 2,000 pounds per year of dental mercury are contained in 
incinerated sewage sludge. 40 CFR part 503, subpart E sets requirements 
for the incineration of mercury and other toxic metals in sludge. For 
mercury, subpart E provides that incineration of sludge must meet the 
requirements of the National Emissions Standards for Mercury in subpart 
E of 40 CFR part 61.
    Environmental assessment of impacts associated with POTW discharges 
of dental mercury is complicated by uncertainties about the fate and 
transport of mercury in aquatic environments. The elemental form of 
mercury used in dentistry has low water solubility and is not readily 
absorbed when ingested by humans, fish, or wildlife. However, elemental 
mercury may be converted into highly toxic methylmercury in aquatic 
environments by certain forms of anaerobic sulfate-reducing bacteria. 
Methylmercury has high potential to become increasingly concentrated up 
through aquatic food chains as larger fish eat smaller fish.

[[Page 27174]]

Fish commonly eaten by humans may have methylmercury levels 100,000 
times that of ambient water. The neurological effects of consumption of 
methylmercury-contaminated fish are well documented. Developmental 
effects to fetuses, infants, children, and fish consumption by women of 
childbearing age are of special concern. Neurological effects from 
predation of methylmercury-contaminated fish have been documented to 
occur in wild populations of fish, birds, and mammals in many areas of 
the United States (DCN DA00202). A plausible link has been identified 
between anthropogenic sources of mercury in the United States and 
methylmercury in fish. However, fish methylmercury concentrations also 
result from existing background concentrations of mercury which may 
consist of mercury from natural sources and atmospheric deposition of 
mercury in the United States from sources in other countries. Given the 
current scientific understanding of the environmental fate and 
transport of mercury, it is not possible to quantify how much of the 
methylmercury in fish consumed by the U.S. population is contributed by 
U.S. emissions relative to international mercury sources or natural 
mercury sources.
    EPA was unable to assess the specific environmental impacts of 
dental mercury discharged by POTWs due to insufficient data needed to 
evaluate several fundamental factors about the discharge, fate, and 
transport of dental mercury in aquatic environments, including: the 
degree and geographic extent of dental mercury methylation in aquatic 
environments, the amount of methylated dental mercury that is taken up 
by fish and wildlife, the human consumption rates of fish contaminated 
with methylated dental mercury, and the extent and magnitude of 
naturally- occurring mercury in aquatic environments.

B. Environmental Benefits

    While EPA did not perform a quantitative environmental benefits 
analysis of the final rule, due to insufficient data about the aquatic 
fate and transport of dental mercury discharged by POTWs, EPA was able 
to assess the qualitative environmental benefits based on existing 
information. For example, EPA identified studies that show that 
decreased point-source discharges of mercury to surface water result in 
lower methylmercury concentrations in fish. Moreover, several studies 
quantify economic benefits from improved human health and ecological 
conditions resulting from lower fish concentrations of methylmercury 
(DCN DA00148). The final pretreatment standards will produce human 
health and ecological benefits by reducing the estimated annual 
nationwide POTW discharge of dental mercury to surface water from 1,003 
pounds to 11 pounds.

XII. Non-Water Quality Environmental Impacts Associated With the 
Technology Basis of the Rule

    Eliminating or reducing one form of pollution may cause other 
environmental problems. Sections 304(b) and 306 of the Clean Water Act 
require EPA to consider non-water quality environmental impacts 
(including energy requirements) associated with effluent limitations 
guidelines and standards. To comply with these requirements, EPA 
considered the potential impact of the technology basis on energy 
consumption, air pollution, and solid waste generation. As shown below, 
EPA anticipates that the rule would produce minimal non-water quality 
environmental impacts and as such determined they are acceptable. 
Additional information about the analysis of these non-water quality 
impacts is contained in the TEDD.

A. Energy Requirements

    Net energy consumption considers the incremental electrical 
requirements associated with operating and maintaining dental amalgam 
separators used in combination with BMPs that form the technology basis 
for the standards. As described in Section V, most amalgam separators 
use sedimentation, either alone or in conjunction with filtration to 
remove solids in the waste stream. Most separators rely on gravity or 
the suction of the existing vacuum system to operate, and do not 
require an additional electrical power source. As noted in Section V, 
some separators have warning indicators that require a battery or power 
source. EPA does not anticipate this would pose any considerable energy 
requirements. Moreover, the addition of an amalgam separator is likely 
to reduce energy consumption at dental offices that do not currently 
employ an amalgam separator as it will prevent small particles from 
impeding the vacuum pump impeller. A clean impeller is more efficient 
than a dirty impeller, and thus will draw less energy (DCN DA00465). 
Upon consideration of all of these factors, EPA concludes there will be 
no significant energy requirements associated with this final rule.

B. Air Emissions

    Unbound mercury is highly volatile and can easily evaporate into 
the atmosphere. An estimated 99.6 percent of dental mercury discharges 
are in solid bound form; i.e. elemental mercury bound to amalgam 
particles (DCN DA00018). Because the majority of dental mercury is 
bound to solid particles, it likely will not volatize to the 
atmosphere. Therefore, EPA expects the final PSES and PSNS will not 
pose any increases in air pollution.

C. Solid Waste Generation

    In the absence of amalgam separators, a portion of the amalgam 
rinsed into chair-side drains is collected by chair-side traps. The 
remainder is discharged to the POTW where the vast majority is removed 
from the wastewater and becomes part of the POTW sludge that may be 
land-applied, disposed of in landfills or mono-fills, or incinerated. 
EPA expect the final rule to increase the use of amalgam separators 
nationwide by one and a half times with a corresponding increase in 
collection and recycling of used amalgam from the spent separator 
canisters. EPA expects the operation and maintenance requirements 
associated with the amalgam separator compliance option included in the 
final rule will further promote recycling as the primary means of 
amalgam waste management, because many amalgam separator manufactures 
and dental office suppliers have begun offering waste handling services 
that send dental amalgam waste to retorting and recycling facilities. 
Nationally, EPA expects less dental amalgam will be discharged to POTWs 
leading to reductions in the amount of mercury discharged to surface 
waters and land-applied, landfilled, or released to the air during 
incineration of sludge. Instead, EPA expects that the waste will be 
collected in separator canisters and recycled. After the amalgam 
containing waste has been recycled, the canisters are either recycled 
or landfilled. For purposes of assessing the incremental solid waste 
generation, EPA conservatively assumes all of the canisters are 
landfilled. EPA finds that if each dental office generated an average 
of 2 pounds of spent canisters per year, the total mass of solid waste 
generated would still comprise less than 0.0001 percent of the 254 
million tons of solid waste generated by Americans annually (DCN 
DA00496). Based on this evaluation of incremental solid waste 
generation, EPA concludes there will not be a significant incremental 
non-water quality impact associated with

[[Page 27175]]

solid waste generation as a result of this final rule.

XIII. Standards for Reference

    This rule references standards from the American National Standards 
Institute/American Dental Association and the International 
Organization for Standardization, and in compliance with the National 
Technology Transfer and Advancement Act (see Section XIV). They are 
available either at EPA's Water Docket (see ADDRESSES section above) 
for inspection, or on their respective Web sites to everyone at a cost 
determined by the respective Web site, generally from $100 to $150. The 
cost of obtaining these standards is not a significant financial burden 
for a discharger or environmental laboratory, making the standards 
reasonably available. The individual standards are discussed in greater 
detail below.
    The installation, operation, and maintenance of one or more amalgam 
separators compliant with either the ADA 2009 standard with the 2011 
addendum, or the ISO standard when removing dental amalgam solids from 
all amalgam process wastewater:
     ANSI/ADA Specification No. 108:2009, American National 
Standard/American Dental Association Specification No. 108 Amalgam 
Separators.
     ANSI/ADA Specification No. 108:2009 Addendum, American 
National Standard/American Dental Association Specification No. 108 
Amalgam Separators, Addendum.
     International Standard ISO 11143;2008, Dentistry--Amalgam 
Separators.

XIV. Statutory and Executive Order Reviews

    Additional information about these statutes and Executive Orders 
can be found at https://www.epa.gov/laws-regulations/laws-and-executive-orders.

A. Executive Order 12866: Regulatory Planning and Review and Executive 
Order 13563: Improving Regulation and Regulatory Review

    This action is a significant regulatory action that was submitted 
to the Office of Management and Budget (OMB) for review because it 
raises novel legal or policy issues. Any changes made in response to 
OMB recommendations have been documented in the docket. The economic 
analysis is available in the docket (DCN DA00458) and is briefly 
summarized in Section IX. The benefits are summarized in Section XI.

B. Paperwork Reduction Act

    The information collection requirements in this final rule have 
been submitted for approval to the OMB under the Paperwork Reduction 
Act, 44 U.S.C. 3501 et seq. The Information Collection Request (ICR) 
document prepared by EPA has been assigned EPA ICR number 2514.02. You 
can find a copy of the ICR in the docket for this rule, and it is 
briefly summarized here. The information collection requirements are 
not enforceable until OMB approves them.
    EPA estimates it would take a total annual average of 402,000 hours 
and $7.2 million for affected dental offices to collect and report the 
information required in the final rule. This estimate includes effort 
for each dental office associated with completing a one-time compliance 
report. EPA based this estimate on average labor rates from the Bureau 
of Labor Statistics for the dental office personnel involved in 
collecting and reporting the information required. EPA estimates it 
would take a total annual average of 34,000 hours and $2.02 million for 
Control Authorities to review the information submitted by dental 
offices. EPA estimates that there would be no start-up or capital costs 
associated with the information described above. Burden is defined at 5 
CFR 1320(b).
    An agency may not conduct or sponsor, and a person is not required 
to respond to, a collection of information unless it displays a 
currently valid OMB control number. The OMB control numbers for EPA's 
regulations are listed in 40 CFR part 9. When OMB approves this ICR, 
the Agency will announce the approval in the Federal Register and 
publish a technical amendment to 40 CFR part 9 to display the OMB 
control number for the approved information collection activities in 
this final rule.

C. Regulatory Flexibility Act

    I certify that this action will not have a significant economic 
impact on a substantial number of small entities under the RFA. The 
small entities subject to the requirements of this action are defined 
as: (1) A small business in the Dental Office sector (NAICS 621210) 
with annual receipts of 7.5 million dollars or less (based on SBA size 
standards); (2) a small governmental jurisdiction that is a government 
of a city, county, town, school district or special district with a 
population of less than 50,000; and (3) a small organization that is 
any not-for- profit enterprise which is independently owned and 
operated and is not dominant in its field.
    The Agency has determined that 116,014 dental offices out of 
116,720 dental offices potentially subject to this final rule meet the 
small business definition. EPA's analysis of projected impacts on small 
dental offices is described in detail in Section IX. EPA projects less 
than 1 percent of 116,720 affected dental offices would incur 
compliance costs exceeding 1 percent of revenue and no more than 0.2 
percent would incur compliance costs exceeding 3 percent of revenue.
    Although this final rule will not have a significant economic 
impact on a substantial number of small entities, EPA nonetheless has 
tried to reduce the impact of this final rule on small entities. First, 
this final rule will allow dental offices with existing separators to 
satisfy the requirements for a period of up to 10 years. Second, EPA 
significantly reduced the rule's reporting requirements for all 
affected dental offices as compared to the reporting requirements for 
other industries with categorical pretreatment standards.

D. Unfunded Mandates Reform Act (UMRA)

    This action does not contain an unfunded mandate of $100 million or 
more as described in UMRA, 2 U.S.C. 1531-1538, and does not 
significantly or uniquely affect small governments. The annual cost of 
the final rule is $59 to $61 million; thus, this final rule is not 
subject to the requirements of sections 202 or 205 of UMRA.
    This final rule is also not subject to the requirements of section 
203 of UMRA, because it contains no regulatory requirements that may 
significantly or uniquely affect small governments. EPA has not 
identified any dental offices that are owned by small governments. 
While this final rule impacts government entities required to 
administer pretreatment standards, small governments will generally not 
be affected. By statute, a small government jurisdiction is defined as 
a government of a city, county, town, school district or special 
district with a population of less than 50,000 (5 U.S.C 601). Control 
authorities are responsible for oversight and administration associated 
with this final rule. A POTW is required to become a Control Authority 
when it (or a combination of POTWs operated by the same authority) has 
a design flow of at least 5 million gallons per day and receives 
pollutants from industrial users that would pass through or interfere 
with the operations and cause a violation of the POTW's NPDES permit. 
The average water use per person is 100 gallons per day so a POTW with 
a

[[Page 27176]]

population less than 50,000 would likely have a flow less than 5 MGD. 
Therefore, EPA does not expect small government owned POTWs to be 
required to become a Control Authority. EPA is aware that some small 
POTWs have approved pretreatment programs so they serve as a Control 
Authority. To the extent small POTWs with pre-existing approved 
pretreatment programs receive dental discharges subject to this rule, 
they would incur some incremental oversight requirements as described 
in Section VI. However, EPA expects such cases to be limited.

E. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have 
substantial direct effects on the states, on the relationship between 
the national government and the states, or on the distribution of power 
and responsibilities among the various levels of government.

F. Executive Order 13175: Consultation and Coordination With Indian 
Tribal Governments

    This final rule does not have tribal implications, as specified in 
Executive Order 13175. It does not have substantial direct effects on 
Tribal governments, on the relationship between the Federal government 
and Indian Tribes, or on the distribution of power and responsibilities 
between the Federal government and Indian Tribes. This final rule 
contains no Federal mandates for Tribal governments and does not impose 
any enforceable duties on Tribal governments. Thus, Executive Order 
13175 does not apply to this final rule.

G. Executive Order 13045: Protection of Children From Environmental 
Health and Safety Risks

    This action is not subject to Executive Order 13045 because it is 
not economically significant as defined in Executive Order 12866, and 
because EPA does not project the environmental health or safety risks 
addressed by this action present a disproportionate risk to children. 
This final rule will reduce the amount of mercury from dental amalgam 
entering POTW's and eventually the nation's waters, which will reduce 
impacts to the neurological development of children.

H. Executive Order 13211: Energy Effects

    This action is not a ``significant energy action'' because it is 
not likely to have a significant adverse effect on the supply, 
distribution or use of energy. EPA determined that any additional 
energy usage would be insignificant to the total energy usage of Dental 
Offices and total annual U.S. energy consumption.

I. National Technology Transfer and Advancement Act

    This final rule involves technical standards. The Agency decided to 
use the American National Standards Institute (ANSI) American National 
Standard/American Dental Association (ADA) Specification 108 for 
Amalgam Separators (2009) with Technical Addendum (2011) or the 
International Organization for Standardization (ISO) 11143 Standard 
(2008) or the International Organization for Standardization (ISO) 
efficiency standards for amalgam separators (ISO 11143) developed in 
1999 and updated in 2008. One approach to meet the standards in this 
rule is to install and operate an amalgam separator(s) compliant with 
one of these standards or their equivalent. These voluntary standard 
setting organizations established a standard for measuring amalgam 
separator efficiency by evaluating the retention of amalgam mercury 
using specified test procedures in a laboratory setting. They also 
include requirements for instructions for use and operation and 
maintenance.

J. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations

    EPA determined that this action does not have disproportionately 
high and adverse human health or environmental effects on minority 
populations, low-income populations, and/or indigenous peoples, as 
specified in Executive Order 12898 (59 FR 7629, February 16, 1994). 
While EPA was unable to perform a detailed environmental justice 
analysis because it lacks data on the location of POTWs to which dental 
discharges currently occur, this final rule will increase the level of 
environmental protection for all affected populations without having 
any disproportionately high and adverse human health or environmental 
effects on any population, including any minority or low-income 
population. This final rule will reduce the amount of mercury from 
dental amalgam entering POTW's and eventually the nation's waters, to 
benefit all of society, including minority communities.

K. Congressional Review Act (CRA)

    This action is subject to the CRA, and EPA will submit a rule 
report to each House of the Congress and to the Comptroller General of 
the United States. This action is not a ``major rule'' as defined by 5 
U.S.C. 804(2).

List of Subjects in 40 CFR Part 441

    Environmental protection, Dental, Dental office, Dentist, Mercury, 
Pretreatment, Waste treatment and disposal, Water pollution control.

    Dated: June 9, 2017.
Michael H. Shapiro,
Acting Assistant Administrator.
    Therefore, 40 CFR part 441 is amended by adding part 441 to read as 
follows:

PART 441--DENTAL OFFICE POINT SOURCE CATEGORY

Sec.
441.10 Applicability.
441.20 General definitions.
441.30 Pretreatment standards for existing sources (PSES).
441.40 Pretreatment standards for new sources (PSNS).
441.50 Reporting and recordkeeping requirements.

    Authority: 33 U.S.C. 1251, 1311, 1314, 1316, 1317, 1318, 1342, 
and 1361. 42 U.S.C. 13101-13103.


Sec.  441.10  Applicability.

    (a) Except as provided in paragraphs (c), (d), and (e) of this 
section, this part applies to dental dischargers.
    (b) Unless otherwise designated by the Control Authority, dental 
dischargers subject to this part are not Significant Industrial Users 
as defined in 40 CFR part 403, and are not ``Categorical Industrial 
Users'' or ``industrial users subject to categorical pretreatment 
standards'' as those terms and variations are used in 40 CFR part 403, 
as a result of applicability of this rule.
    (c) This part does not apply to dental dischargers that exclusively 
practice one or more of the following dental specialties: Oral 
pathology, oral and maxillofacial radiology, oral and maxillofacial 
surgery, orthodontics, periodontics, or prosthodontics.
    (d) This part does not apply to wastewater discharges from a mobile 
unit operated by a dental discharger.
    (e) This part does not apply to dental dischargers that do not 
discharge any amalgam process wastewater to a POTW, such as dental 
dischargers that collect all dental amalgam process wastewater for 
transfer to a Centralized Waste Treatment facility as defined in 40 CFR 
part 437.
    (f) Dental Dischargers that do not place dental amalgam, and do not 
remove amalgam except in limited emergency or unplanned, unanticipated 
circumstances, and that certify such to

[[Page 27177]]

the Control Authority as required in Sec.  441.50 are exempt from any 
further requirements of this part.


Sec.  441.20  General definitions.

    For purposes of this part:
    (a) Amalgam process wastewater means any wastewater generated and 
discharged by a dental discharger through the practice of dentistry 
that may contain dental amalgam.
    (b) Amalgam separator means a collection device designed to capture 
and remove dental amalgam from the amalgam process wastewater of a 
dental facility.
    (c) Control Authority is defined in 40 CFR 403.3(f).
    (d) Dental amalgam means an alloy of elemental mercury and other 
metal(s) that is used in the practice of dentistry.
    (e) Dental Discharger means a facility where the practice of 
dentistry is performed, including, but not limited to, institutions, 
permanent or temporary offices, clinics, home offices, and facilities 
owned and operated by Federal, state or local governments, that 
discharges wastewater to a publicly owned treatment works (POTW).
    (f) Duly Authorized Representative is defined in 40 CFR 
403.12(l)(3).
    (g) Existing Sources means a dental discharger that is not a new 
source.
    (h) Mobile unit means a specialized mobile self-contained van, 
trailer, or equipment used in providing dentistry services at multiple 
locations.
    (i) New Sources means a dental discharger whose first discharge to 
a POTW occurs after July 14, 2017.
    (j) Publicly Owned Treatment Works is defined in 40 CFR 403.3(q).


Sec.  441.30  Pretreatment standards for existing sources (PSES).

    No later than July 14, 2020, any existing source subject to this 
part must achieve the following pretreatment standards:
    (a) Removal of dental amalgam solids from all amalgam process 
wastewater by one of the following methods:
    (1) Installation, operation, and maintenance of one or more amalgam 
separators that meet the following requirements:
    (i) Compliant with either the American National Standards Institute 
(ANSI) American National Standard/American Dental Association (ADA) 
Specification 108 for Amalgam Separators (2009) with Technical Addendum 
(2011) or the International Organization for Standardization (ISO) 
11143 Standard (2008) or subsequent versions so long as that version 
requires amalgam separators to achieve at least a 95% removal 
efficiency. Compliance must be assessed by an accredited testing 
laboratory under ANSI's accreditation program for product certification 
or a testing laboratory that is a signatory to the International 
Laboratory Accreditation Cooperation's Mutual Recognition Arrangement. 
The testing laboratory's scope of accreditation must include ANSI/ADA 
108-2009 or ISO 11143.
    (ii) The amalgam separator(s) must be sized to accommodate the 
maximum discharge rate of amalgam process wastewater.
    (iii) A dental discharger subject to this part that operates an 
amalgam separator that was installed at a dental facility prior to June 
14, 2017, satisfies the requirements of paragraphs (a)(1)(i) and (ii) 
of this section until the existing separator is replaced as described 
in paragraph (a)(1)(v) of this section or until June 14, 2017, 
whichever is sooner.
    (iv) The amalgam separator(s) must be inspected in accordance with 
the manufacturer's operating manual to ensure proper operation and 
maintenance of the separator(s) and to confirm that all amalgam process 
wastewater is flowing through the amalgam retaining portion of the 
amalgam separator(s).
    (v) In the event that an amalgam separator is not functioning 
properly, the amalgam separator must be repaired consistent with 
manufacturer instructions or replaced with a unit that meets the 
requirements of paragraphs (a)(i) and (ii) of this section as soon as 
possible, but no later than 10 business days after the malfunction is 
discovered by the dental discharger, or an agent or representative of 
the dental discharger.
    (vi) The amalgam retaining units must be replaced in accordance 
with the manufacturer's schedule as specified in the manufacturer's 
operating manual or when the amalgam retaining unit has reached the 
maximum level, as specified by the manufacturer in the operating 
manual, at which the amalgam separator can perform to the specified 
efficiency, whichever comes first.
    (2) Installation, operation, and maintenance of one or more amalgam 
removal device(s) other than an amalgam separator. The amalgam removal 
device must meet the following requirements:
    (i) Removal efficiency of at least 95 percent of the mass of solids 
from all amalgam process wastewater. The removal efficiency must be 
calculated in grams recorded to three decimal places, on a dry weight 
basis. The removal efficiency must be demonstrated at the maximum water 
flow rate through the device as established by the device 
manufacturer's instructions for use.
    (ii) The removal efficiency must be determined using the average 
performance of three samples. The removal efficiency must be 
demonstrated using a test sample of dental amalgam that meets the 
following particle size distribution specifications: 60 percent by mass 
of particles that pass through a 3150 [micro]m sieve but which do not 
pass through a 500 [micro]m sieve, 10 percent by mass of particles that 
pass through a 500 [micro]m sieve but which do not pass through a 100 
[micro]m sieve, and 30 percent by mass of particles that pass through a 
100 [micro]m sieve. Each of these three specified particle size 
distributions must contain a representative distribution of particle 
sizes.
    (iii) The device(s) must be sized to accommodate the maximum 
discharge rate of amalgam process wastewater.
    (iv) The devices(s) must be accompanied by the manufacturer's 
manual providing instructions for use including the frequency for 
inspection and collecting container replacement such that the unit is 
replaced once it has reached the maximum filling level at which the 
device can perform to the specified efficiency.
    (v) The device(s) must be inspected in accordance with the 
manufacturer's operation manual to ensure proper operation and 
maintenance, including confirmation that amalgam process wastewater is 
flowing through the amalgam separating portion of the device(s).
    (vi) In the event that a device is not functioning properly, it 
must be repaired consistent with manufacturer instructions or replaced 
with a unit that meets the requirements of paragraphs (a)(2)(i) through 
(iii) of this section as soon as possible, but no later than 10 
business days after the malfunction is discovered by the dental 
discharger, or an agent or representative of the dental discharger.
    (vii) The amalgam retaining unit(s) of the device(s) must be 
replaced as specified in the manufacturer's operating manual, or when 
the collecting container has reached the maximum filling level, as 
specified by the manufacturer in the operating manual, at which the 
amalgam separator can perform to the specified efficiency, whichever 
comes first.
    (viii) The demonstration of the device(s) under paragraphs 
(a)(2)(i) through (iii) of this section must be documented in the One-
Time Compliance Report.
    (b) Implementation of the following best management practices 
(BMPs):

[[Page 27178]]

    (1) Waste amalgam including, but not limited to, dental amalgam 
from chair-side traps, screens, vacuum pump filters, dental tools, 
cuspidors, or collection devices, must not be discharged to a POTW.
    (2) Dental unit water lines, chair-side traps, and vacuum lines 
that discharge amalgam process wastewater to a POTW must not be cleaned 
with oxidizing or acidic cleaners, including but not limited to bleach, 
chlorine, iodine and peroxide that have a pH lower than 6 or greater 
than 8.
    (c) All material is available for inspection at EPA's Water Docket, 
EPA West, 1301 Constitution Avenue NW., Room 3334, Washington, DC 
20004, Telephone: 202-566-2426, and is available from the sources 
listed below.
    (1) The following standards are available from the American Dental 
Association (ADA), 211 East Chicago Ave., Chicago IL 60611-2678, 
Telephone 312-440-2500, https://www.ada.org.
    (i) ANSI/ADA Specification No. 108:2009, American National 
Standard/American Dental Association Specification No. 108 Amalgam 
Separators. February 2009.
    (ii) ANSI/ADA Specification No. 108:2009 Addendum, American 
National Standard/American Dental Association Specification No. 108 
Amalgam Separators, Addendum. November 2011.
    (2) The following standards are available from the American 
National Standards Institute (ANSI), 25 West 43rd Street, 4th Floor, 
New York, NY 10036, Telephone 212-642-4900, https://webstore.ansi.org.
    (i) International Standard ISO 11143:2008, Dentistry--Amalgam 
Separators. Second edition, July 1, 2008.
    (ii) [Reserved]


Sec.  441.40  Pretreatment standards for new sources (PSNS).

    As of July 14, 2017, any new source subject to this part must 
comply with the requirements of Sec.  441.30(a) and (b) and the 
reporting and recordkeeping requirements of Sec.  441.50.


Sec.  441.50  Reporting and recordkeeping requirements.

    (a) Dental Dischargers subject to this part must comply with the 
following reporting requirements in lieu of the otherwise applicable 
requirements in 40 CFR 403.12(b), (d), (e), and (g).
    (1) One-Time Compliance Report deadlines. For existing sources, a 
One-Time Compliance Report must be submitted to the Control Authority 
no later than October 12, 2020, or 90 days after a transfer of 
ownership. For new sources, a One-Time Compliance Report must be 
submitted to the Control Authority no later than 90 days following the 
introduction of wastewater into a POTW.
    (2) Signature and certification. The One-Time Compliance Report 
must be signed and certified by a responsible corporate officer, a 
general partner or proprietor if the dental discharger is a partnership 
or sole proprietorship, or a duly authorized representative in 
accordance with the requirements of 40 CFR 403.12(l).
    (3) Contents. (i) The One-Time Compliance Report for dental 
dischargers subject to this part that do not place or remove dental 
amalgam as described at Sec.  441.10(f) must include the: facility 
name, physical address, mailing address, contact information, name of 
the operator(s) and owner(s); and a certification statement that the 
dental discharger does not place dental amalgam and does not remove 
amalgam except in limited circumstances.
    (ii) The One-Time Compliance Report for dental dischargers subject 
to the standards of this part must include:
    (A) The facility name, physical address, mailing address, and 
contact information.
    (B) Name(s) of the operator(s) and owner(s).
    (C) A description of the operation at the dental facility 
including: The total number of chairs, the total number of chairs at 
which dental amalgam may be present in the resulting wastewater, and a 
description of any existing amalgam separator(s) or equivalent 
device(s) currently operated to include, at a minimum, the make, model, 
year of installation.
    (D) Certification that the amalgam separator(s) or equivalent 
device is designed and will be operated and maintained to meet the 
requirements specified in Sec.  441.30 or Sec.  441.40.
    (E) Certification that the dental discharger is implementing BMPs 
specified in Sec.  441.30(b) or Sec.  441.40(b) and will continue to do 
so.
    (F) The name of the third-party service provider that maintains the 
amalgam separator(s) or equivalent device(s) operated at the dental 
office, if applicable. Otherwise, a brief description of the practices 
employed by the facility to ensure proper operation and maintenance in 
accordance with Sec.  441.30 or Sec.  441.40.
    (4) Transfer of ownership notification. If a dental discharger 
transfers ownership of the facility, the new owner must submit a new 
One-Time Compliance Report to the Control Authority no later than 90 
days after the transfer.
    (5) Retention period. As long as a Dental Discharger subject to 
this part is in operation, or until ownership is transferred, the 
Dental Discharger or an agent or representative of the dental 
discharger must maintain the One-Time Compliance Report required at 
paragraph (a) of this section and make it available for inspection in 
either physical or electronic form.
    (b) Dental Dischargers or an agent or representative of the dental 
discharger must maintain and make available for inspection in either 
physical or electronic form, for a minimum of three years:
    (1) Documentation of the date, person(s) conducting the inspection, 
and results of each inspection of the amalgam separator(s) or 
equivalent device(s), and a summary of follow-up actions, if needed.
    (2) Documentation of amalgam retaining container or equivalent 
container replacement (including the date, as applicable).
    (3) Documentation of all dates that collected dental amalgam is 
picked up or shipped for proper disposal in accordance with 40 CFR 
261.5(g)(3), and the name of the permitted or licensed treatment, 
storage or disposal facility receiving the amalgam retaining 
containers.
    (4) Documentation of any repair or replacement of an amalgam 
separator or equivalent device, including the date, person(s) making 
the repair or replacement, and a description of the repair or 
replacement (including make and model).
    (5) Dischargers or an agent or representative of the dental 
discharger must maintain and make available for inspection in either 
physical or electronic form the manufacturers operating manual for the 
current device.

[FR Doc. 2017-12338 Filed 6-12-17; 11:15 am]
 BILLING CODE 6560-50-P