benchmarks were not available at a programmatic or regional level, we
used benchmarks developed by other agencies (e.g., NOAA) or by state
agencies.
    In all cases (except for lead compounds, which were evaluated
through a comparison to the NAAQS), we searched for benchmarks at the
following three effect levels, as described in section III.A.5 of this
preamble:
    1. A no-effect level (i.e., NOAEL).
    2. Threshold-effect level (i.e., LOAEL).
    3. Probable effect level (i.e., PEL).
    For some ecological assessment endpoint/environmental HAP
combinations, we could identify benchmarks for all three effect levels,
but for most, we could not. In one case, where different agencies
derived significantly different numbers to represent a threshold for
effect, we included both. In several cases, only a single benchmark was
available. In cases where multiple effect levels were available for a
particular PB-HAP and assessment endpoint, we used all of the available
effect levels to help us to determine whether risk exists and if the
risks could be considered significant and widespread.
    The EPA evaluates the following seven HAP in the environmental risk
screening assessment: Cadmium, dioxins/furans, POM, mercury (both
inorganic mercury and methyl mercury), lead compounds, HCl, and HF,
where applicable. These seven HAP represent pollutants that can cause
adverse impacts for plants and animals either through direct exposure
to HAP in the air or through exposure to HAP that is deposited from the
air onto soils and surface waters. These seven HAP also represent those
HAP for which we can conduct a meaningful environmental risk screening
assessment. For other HAP not included in our screening assessment, the
model has not been parameterized such that it can be used for that
purpose. In some cases, depending on the HAP, we may not have
appropriate multipathway models that allow us to predict the
concentration of that pollutant. The EPA acknowledges that other HAP
beyond the seven HAP that we are evaluating may have the potential to
cause adverse environmental effects and, therefore, the EPA may
evaluate other relevant HAP in the future, as modeling science and
resources allow.
    Further information on uncertainties and the Tier 1 and 2
environmental screening methods is provided in Appendix 5 of the
document, Technical Support Document for TRIM-Based Multipathway Tiered
Screening Methodology for RTR: Summary of Approach and Evaluation.
Also, see the Residual Risk Report, available in the docket for this
action.

B. How did we consider the risk results in making decisions for this
proposal?

    As discussed in section II.A of this preamble, in evaluating and
developing standards under CAA section 112(f)(2), we apply a two-step
process to address residual risk. In the first step, the EPA

determines whether risks are acceptable. This determination ``considers
all health information, including risk estimation uncertainty, and
includes a presumptive limit on maximum individual lifetime [cancer]
risk (MIR) \25\ of approximately [1-in-10 thousand] [i.e., 100-in-1
million].'' 54 FR 38045, September 14, 1989. If risks are unacceptable,
the EPA must determine the emissions standards necessary to bring risks
to an acceptable level without considering costs. In the second step of
the process, the EPA considers whether the emissions standards provide
an ample margin of safety ``in consideration of all health information,
including the number of persons at risk levels higher than
approximately 1-in-1 million, as well as other relevant factors,
including costs and economic impacts, technological feasibility, and
other factors relevant to each particular decision.'' Id. The EPA must
promulgate emission standards necessary to provide an ample margin of
safety. After conducting the ample margin of safety analysis, we
consider whether a more stringent standard is necessary to prevent,
taking into consideration, costs, energy, safety, and other relevant
factors, an adverse environmental effect.
---------------------------------------------------------------------------

    \25\ Although defined as ``maximum individual risk,'' MIR refers
only to cancer risk. MIR, one metric for assessing cancer risk, is
the estimated risk were an individual exposed to the maximum level
of a pollutant for a lifetime.
---------------------------------------------------------------------------

    In past residual risk actions, the EPA considered a number of human
health risk metrics associated with emissions from the categories under
review, including the MIR, the number of persons in various risk
ranges, cancer incidence, the maximum non-cancer HI and the maximum
acute non-cancer hazard. See, e.g., 72 FR 25138, May 3, 2007; and 71 FR
42724, July 27, 2006. The EPA considered this health information for
both actual and allowable emissions. See, e.g., 75 FR 65068, October
21, 2010; 75 FR 80220, December 21, 2010; 76 FR 29032, May 19, 2011.
The EPA also discussed risk estimation uncertainties and considered the
uncertainties in the determination of acceptable risk and ample margin
of safety in these past actions. The EPA considered this same type of
information in support of this action.
    The Agency is considering these various measures of health
information to inform our determinations of risk acceptability and
ample margin of safety under CAA section 112(f). As explained in the
Benzene NESHAP, ``the first step judgment on acceptability cannot be
reduced to any single factor'' and, thus, ``[t]he Administrator
believes that the acceptability of risk under [previous] section 112 is
best judged on the basis of a broad set of health risk measures and
information.'' 54 FR 38046, September 14, 1989. Similarly, with regard
to the ample margin of safety determination, ``the Agency again
considers all of the health risk and other health information
considered in the first step. Beyond that information, additional
factors relating to the appropriate level of control will also be
considered, including cost and economic impacts of controls,
technological feasibility, uncertainties, and any other relevant
factors.'' Id.
    The Benzene NESHAP approach provides flexibility regarding factors
the EPA may consider in making determinations and how the EPA may weigh
those factors for each source category. In responding to comment on our
policy under the Benzene NESHAP, the EPA explained that:

``[t]he policy chosen by the Administrator permits consideration of
multiple measures of health risk. Not only can the MIR figure be
considered, but also incidence, the presence of non-cancer health
effects, and the uncertainties of the risk estimates. In this way,
the effect on the most exposed individuals can be reviewed as well
as the impact on the general public. These factors can then be
weighed in each individual case. This approach complies with the
Vinyl Chloride mandate that the Administrator ascertain an
acceptable level of risk to the public by employing [her] expertise
to assess available data. It also complies with the Congressional
intent behind the CAA, which did not exclude the use of any
particular measure of public health risk from the EPA's
consideration with respect to CAA section 112 regulations, and
thereby implicitly permits consideration of any and all measures of
health risk which the Administrator, in [her] judgment, believes are
appropriate to determining what will `protect the public health'.''

    See 54 FR at 38057, September 14, 1989. Thus, the level of the MIR
is only one factor to be weighed in determining acceptability of risks.
The Benzene NESHAP explained that ``an MIR of approximately one in 10
thousand should ordinarily be the upper end of the range of
acceptability. As risks increase above this benchmark, they become
presumptively less acceptable under CAA section 112, and would be
weighed with the other health risk measures and information in making
an overall judgment on acceptability. Or, the Agency may find, in a
particular case, that a risk that includes MIR less than the
presumptively acceptable level is unacceptable in the light of other
health risk factors.'' Id. at 38045. Similarly, with regard to the
ample margin of safety analysis, the EPA stated in the Benzene NESHAP
that: ``EPA believes the relative weight of the many factors that can
be considered in selecting an ample margin of safety can only be
determined for each specific source category. This occurs mainly
because technological and economic factors (along with the health-
related factors) vary from source category to source category.'' Id. at
38061. We also consider the uncertainties associated with the various
risk analyses, as discussed earlier in this preamble, in our
determinations of acceptability and ample margin of safety.
    The EPA notes that it has not considered certain health information
to date in making residual risk determinations. At this time, we do not
attempt to quantify those HAP risks that may be associated with
emissions from other facilities that do not include the source
categories in question, mobile source emissions, natural source
emissions, persistent environmental pollution, or atmospheric
transformation in the vicinity of the sources in these categories.
    The Agency understands the potential importance of considering an
individual's total exposure to HAP in addition to considering exposure
to HAP emissions from the source category and facility. We recognize
that such consideration may be particularly important when assessing
non-cancer risks, where pollutant-specific exposure health reference
levels (e.g., RfCs) are based on the assumption that thresholds exist
for adverse health effects. For example, the Agency recognizes that,
although exposures attributable to emissions from a source category or
facility alone may not indicate the potential for increased risk of
adverse non-cancer health effects in a population, the exposures
resulting from emissions from the facility in combination with
emissions from all of the other sources (e.g., other facilities) to
which an individual is exposed may be sufficient to result in increased
risk of adverse non-cancer health effects. In May 2010, the SAB advised
the EPA ``that RTR assessments will be most useful to decision makers
and communities if results are presented in the broader context of
aggregate and cumulative risks, including background concentrations and
contributions from other sources in the area.'' \26\
---------------------------------------------------------------------------

    \26\ The EPA's responses to this and all other key
recommendations of the SAB's advisory on RTR risk assessment
methodologies (which is available at: http://yosemite.epa.gov/sab/
sabproduct.nsf/4AB3966E263D943A8525771F00668381/$File/EPA-SAB-10-
007-unsigned.pdf) are outlined in a memorandum to this rulemaking
docket from David Guinnup titled, EPA's Actions in Response to the
Key Recommendations of the SAB Review of RTR Risk Assessment
Methodologies.

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

    In response to the SAB recommendations, the EPA is incorporating
cumulative risk analyses into its RTR risk assessments, including those
reflected in this proposal. The Agency is: (1) Conducting facility-wide
assessments, which include source category emission points, as well as
other emission points within the facilities; (2) considering sources in
the same category whose emissions result in exposures to the same
individuals; and (3) for some persistent and bioaccumlative pollutants,
analyzing the ingestion route of exposure. In addition, the RTR risk
assessments have always considered aggregate cancer risk from all
carcinogens and aggregate non-cancer HI from all non-carcinogens
affecting the same target organ system.
    Although we are interested in placing source category and facility-
wide HAP risks in the context of total HAP risks from all sources
combined in the vicinity of each source, we are concerned about the
uncertainties of doing so. Because of the contribution to total HAP
risk from emission sources other than those that we have studied in
depth during this RTR review, such estimates of total HAP risks would
have significantly greater associated uncertainties than the source
category or facility-wide estimates. Such aggregate or cumulative
assessments would compound those uncertainties, making the assessments
too unreliable.

C. How did we perform the technology review?

    Our technology review focused on the identification and evaluation
of developments in practices, processes, and control technologies that
have occurred since the MACT standards were promulgated. Where we
identified such developments, in order to inform our decision of
whether it is ``necessary'' to revise the emissions standards, we
analyzed the technical feasibility of applying these developments and
the estimated costs, energy implications, non-air environmental
impacts, as well as considering the emission reductions. We also
considered the appropriateness of applying controls to new sources
versus retrofitting existing sources.
    Based on our analyses of the available data and information, we
identified potential developments in practices, processes, and control
technologies. For this exercise, we considered any of the following to
be a ``development'':
     Any add-on control technology or other equipment that was
not identified and considered during development of the original MACT
standards;
     Any improvements in add-on control technology or other
equipment (that were identified and considered during development of
the original MACT standards) that could result in additional emissions
reduction;
     Any work practice or operational procedure that was not
identified or considered during development of the original MACT
standards;
     Any process change or pollution prevention alternative
that could be broadly applied to the industry and that was not
identified or considered during development of the original MACT
standards; and
     Any significant changes in the cost (including cost
effectiveness) of applying controls (including controls the EPA
considered during the development of the original MACT standards).
    In addition to reviewing the practices, processes, and control
technologies that were considered at the time we originally developed
(or last updated) the NESHAP, we reviewed a variety of data sources in
our investigation of potential practices, processes, or controls to
consider. Among the sources we reviewed were the NESHAP for various
industries that were promulgated since the MACT standards being
reviewed in this action. We reviewed the regulatory requirements and/or
technical analyses associated with these regulatory actions to identify
any practices, processes, and control technologies considered in these
efforts that could be applied to emission sources in the POTW source
category, as well as the costs, non-air impacts, and energy
implications associated with the use of these technologies.
Additionally, we requested information from facilities regarding
developments in practices, processes, or control technology. Finally,
we reviewed information from other sources, such as state and/or local
permitting agency databases and industry-supported databases.

IV. Analytical Results and Proposed Decisions

A. What are the results of the risk assessment and analyses?

1. Inhalation Risk Assessment Results
    Table 2 of this preamble provides an overall summary of the results
of the inhalation risk assessment.

                                                    Table 2--POTW Inhalation Risk Assessment Results
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                          Estimated
                                           Estimated population at      annual cancer      Maximum
Maximum individual cancer risk (1-in-1     increased risk levels of       incidence     chronic non-       Maximum screening acute non-cancer HQ \3\
             million) \1\                           cancer               (cases per     cancer TOSHI
                                                                            year)            \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                    Actual Emissions
--------------------------------------------------------------------------------------------------------------------------------------------------------
0.8...................................  >= 1-in-1 million: 0.........          0.0006           0.007  HQREL = 2 (formaldehyde).
                                        >= 10-in-1 million: 0
                                        >= 100-in-1 million: 0
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                 Allowable Emissions \4\
--------------------------------------------------------------------------------------------------------------------------------------------------------
2.....................................  >= 1-in-1 million: 240.......           0.001            0.01
                                        >= 10-in-1 million: 0
                                        >= 100-in-1 million: 0
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Estimated maximum individual excess lifetime cancer risk due to HAP emissions from the source category.
\2\ Maximum TOSHI. The target organ with the highest TOSHI for POTW source category for both actual and allowable emissions is the respiratory system.
\3\ See section III.A.3 of this preamble for explanation of acute dose-response values. Acute assessments are not performed on allowable emissions.
\4\ The development of allowable emission estimates can be found in the memorandum titled Inputs to the Publicly Owned Treatment Works March 2016
  Residual Risk Modeling, June 2016 (Modeling Inputs Memo), which is available in the docket.

    The results of the chronic baseline inhalation cancer risk
assessment indicate that, based on estimates of current actual
emissions, the MIR posed for the POTW source category is 0.8-in-1
million, with emissions of formaldehyde from the primary clarifier
accounting for the majority of the risk. The total estimated cancer
incidence from POTW based on actual emission levels is 0.0006 excess
cancer cases per year or one case every 1,667 years, with emissions of
formaldehyde and acrylonitrile contributing 50 percent and 21 percent,
respectively, to the cancer incidence.
    When considering MACT-allowable emissions, the MIR is estimated to
be up to 2-in-1 million, driven by emissions of formaldehyde from the
primary clarifier. The cancer incidence is estimated to be 0.001 excess
cancer cases per year, or one excess case in every 1,000 years.
Approximately 240 people are estimated to have cancer risks greater
than or equal to 1-in-1 million considering allowable emissions from
the POTW source category.
    The maximum modeled chronic non-cancer HI (TOSHI) for the source
category based on actual emissions is estimated to be 0.007, driven by
formaldehyde emissions from the primary clarifier. When considering
MACT-allowable emissions, the maximum chronic non-cancer TOSHI is
estimated to be 0.01, driven by formaldehyde emissions.
2. Acute Risk Results
    Our screening analysis for worst-case acute impacts based on actual
emissions indicates the potential for one pollutant, formaldehyde, from
one facility, to have an HQ above 1, based on the formaldehyde REL. Six
out of seven POTW treatment plants had an estimated worst-case HQ less
than or equal to 1 for all HAP.
    To better characterize the potential health risks associated with
the estimated worst-case acute exposure to HAP from the POTW source
category, and in response to a key recommendation from the SAB's peer
review of the EPA's CAA section 112(f) RTR risk assessment
methodologies, we examine a wider range of available acute health
metrics than we do for our chronic risk assessments. This is because
there generally are greater uncertainties associated with the use of
acute reference values.
    By definition, the acute CalEPA REL represents a health-protective
level of exposure, with no risk anticipated below those levels, even
for repeated exposures; however, the health risk from higher-level
exposures is unknown. Therefore, when a CalEPA REL is exceeded and an
AEGL-1 or ERPG-1 level (i.e., levels at which mild effects are
anticipated in the general public for a single exposure) is available,
we have used them as a second comparative measure. For the purpose of
characterizing public health risks in RTR assessments, we typically
have not compared estimated maximum off-site 1-hour exposure levels to
occupational levels. This is because occupational ceiling values are
not generally considered protective for the general public since they
are designed to protect the worker population (presumed healthy adults)
against short-duration (less than 15-minutes) exposures. As a result,
for most chemicals, the 15-minute occupational ceiling values are
higher than a 1-hour AEGL-1 and/or ERPG-1, making comparisons to them
irrelevant unless the AEGL-1 or ERPG-1 levels are also exceeded.
    The worst-case maximum estimated 1-hour exposure to formaldehyde
outside the POTW treatment plant fenceline exceeds the 1-hour REL by
about a factor of 2 (HQREL=2) but is substantially less than
the AEGL-1 and ERPG-1 values for formaldehyde (HQAEGL-1 =
0.2 and HQERPG-1 = 0.2). All other HAP in this analysis have
worst-case acute HQs of 1 or less, indicating little to no potential
for acute health risk.
    In characterizing the potential for acute non-cancer impacts of
concern, it is important to remember the upward bias of these exposure
estimates. First, peak 1-hour emissions were conservatively assumed to
be 10 times the annual emission rate. It was then assumed that
emissions from all emission points at a given POTW peaked concurrently,
and at the same time worst-case hourly meteorology was occurring.
Finally, it was assumed that a person would be located at the point of
maximum concentration for at least an hour. When these factors are
taken together, there is likely little potential for acute health risk
from POTW emissions.
3. Multipathway Risk Screening Results
    PB-HAP emissions of 2-methylnaphthalene (i.e., the only PB-HAP
emitted from the POTW source category) did not exceed the worst-case
Tier I screening emission rate. No other PB-HAP are emitted by any
source in the source category.
4. Environmental Risk Screening Results
    As described in section III.A of this preamble, we conducted a
screening-level evaluation of the potential for adverse environmental
effects associated with emissions of 2-methylnaphthalene.
    In the Tier 1 screening analysis for 2-methylnaphthalene, the
modeled Tier 1 concentrations of this PB-HAP did not exceed any
ecological benchmarks for any POTW in the source category.
5. Facility-Wide Risk Results
    The facility-wide chronic MIR and TOSHI were estimated based on
emissions from all sources at the identified facilities (both MACT and
non-MACT sources). The results of the facility-wide assessment of
cancer risks indicate that three facilities with POTW operations have a
facility-wide cancer MIR greater than or equal to 1-in-1 million. The
maximum facility-wide cancer MIR is 10-in-1 million, primarily driven
by formaldehyde. The maximum facility-wide TOSHI for the source
category is estimated to be 0.09, primarily driven by emissions of
formaldehyde.
6. What demographic groups might benefit from this regulation?
    To examine the potential for any environmental justice (EJ)
concerns that might be associated with the source category, we
performed a demographic analysis of the population close to the
facilities. In this analysis, we evaluated the distribution of HAP-
related cancer and non-cancer risks from the POTW source category
across different social, demographic, and economic groups within the
populations living near facilities identified as having the highest
risks. The methodology and the results of the demographic analyses are
included in a technical report, Risk and Technology Review--Analysis of
Socio-Economic Factors for Populations Living Near POTW Facilities,
available in the docket for this action.
    The results of the demographic analysis are summarized in Table 3
of this preamble. These results, for various demographic groups, are
based on the estimated risks from actual emissions levels for the
population living within 50 km of the facilities.

                                 Table 3--POTW Demographic Risk Analysis Results
----------------------------------------------------------------------------------------------------------------
                                                                                Population
                                                                                with cancer     Population
                                                                                risk at or     with chronic
                                                                    Nationwide     above 1-in-1    hazard index
                                                                                million due to  above 1 due to
                                                                                POTW            POTW
----------------------------------------------------------------------------------------------------------------
Total Population................................................     312,861,265               0               0
----------------------------------------------------------------------------------------------------------------
                                                 Race by Percent
----------------------------------------------------------------------------------------------------------------
White...........................................................              72               0               0
All Other Races.................................................              28               0               0
----------------------------------------------------------------------------------------------------------------
                                                 Race by Percent
----------------------------------------------------------------------------------------------------------------
White...........................................................              72               0               0
African American................................................              13               0               0
Native American.................................................             1.1               0               0
Other and Multiracial...........................................              14               0               0
----------------------------------------------------------------------------------------------------------------
                                              Ethnicity by Percent
----------------------------------------------------------------------------------------------------------------
Hispanic........................................................              17               0               0
Non-Hispanic....................................................              83               0               0
----------------------------------------------------------------------------------------------------------------
                                                Income by Percent
----------------------------------------------------------------------------------------------------------------
Below Poverty Level.............................................              14               0               0
Above Poverty Level.............................................             +86               0               0
----------------------------------------------------------------------------------------------------------------
                                              Education by Percent
----------------------------------------------------------------------------------------------------------------
Over 25 and without High School Diploma.........................              15               0               0
Over 25 and with a High School Diploma..........................              85               0               0
----------------------------------------------------------------------------------------------------------------

    The results of the POTW source category demographic analysis
indicate that emissions from the source category expose no person to a
cancer risk at or above 1-in-1 million or to a chronic non-cancer TOSHI
greater than 1. The demographics of the population living within 50 km
of POTW can be found in Table 2 of the document: Risk and Technology
Review--Analysis of Socio-Economic Factors for Populations Living Near
Publicly Owned Treatment Works.

B. What are our proposed decisions regarding risk acceptability, ample
margin of safety, and adverse environmental effects?

1. Risk Acceptability
    As noted in section II.A.1 of this preamble, the EPA sets standards
under CAA section 112(f)(2) using ``a two-step standard-setting
approach, with an analytical first step to determine an `acceptable
risk' that considers all health information, including risk estimation
uncertainty, and includes a presumptive limit on MIR of approximately 1
in 10 thousand.'' 54 FR 38045, September 14, 1989.
    In determining whether risks are acceptable for the POTW source
category, the EPA considered all available health information including
any uncertainty in risk estimates. Also, as noted in section IV.A of
this preamble, the Agency estimated risk from both actual and allowable
emissions. While there are uncertainties associated with both the
actual and allowable emissions, we consider the allowable emissions to
be an upper bound, based on the conservative methods we used to
calculate allowable emissions.
    The estimated inhalation cancer risk based on actual emissions is
less than 1-in-1 million. Additionally, the estimated inhalation cancer
risk based on allowable emissions is 10-in-1 million. Both of these
results are considerably less than the presumptive limit of
acceptability (i.e., 100-in-1 million). The maximum chronic inhalation
non-cancer hazard indices for both the actual and allowable emissions
are less than 1, indicating that chronic exposures are without
appreciable risk of non-cancer health effects.
    The multipathway screening analysis indicates that PB-HAP emissions
did not exceed the screening emission rates for any PB-HAP evaluated.
    The screening assessment of worst-case acute inhalation exposures
resulting from actual emissions indicates that the worst-case maximum
estimated 1-hour exposure to formaldehyde outside the facility fence
line exceeds the 1-hour REL by a factor of 2 (HQREL = 2). It
is important to note that this highest offsite HQ value assumes an
hourly emissions multiplier of 10 times the annual emissions rate,
while also assuming that a person will be present at the location of
highest exposure for at least 1 hour when emissions from all emission
points are at their peak. We further assume these peak emissions are
occurring at same time worst-case meteorology is occurring. Finally, it
is important to note that this conservatively estimated 1-hour
formaldehyde concentration is well below the AEGL-1 and ERPG-1 for
formaldehyde. Taken together, we believe there is little potential for
acute health risk from formaldehyde. All other HAP in this analysis
have worst-case acute HQ values outside facility fencelines of 1 or
less indicating little potential risk of acute health effects.
    Considering all of the health risk information and factors
discussed above, including the uncertainties discussed in section
III.A.7 of this preamble, the EPA proposes that additional standards
are not necessary to bring risk to an acceptable level because cancer
risks are well below the presumptive limit of acceptability, and

other health risk information indicates there is minimal likelihood of
adverse non-cancer (including chronic, acute, and multipathway) health
effects due to HAP emissions from this source category.
2. Ample Margin of Safety Analysis
    In the ample margin of safety analysis, we evaluate available
control technologies and other measures (including those evaluated
under the technology review, as well as the risk reductions achieved by
such potential additional measures, to determine whether additional
standards are required to reduce risks further. In conducting the ample
margin of safety analysis we consider the costs and economic impacts
and technological feasibility of additional standards.
    We are proposing that the 2002 POTW NESHAP requirements provide an
ample margin of safety to protect public health. As explained in
section IV.A of this preamble, we estimate that the MIR in the exposed
population is less than 1-in-1 million at the actual emission levels.
Additionally, the chronic non-cancer TOSHI is less than 1 and there is
negligible potential for acute risk. Thus, EPA proposes that standards
in the 2002 POTW NESHAP achieve the goal of providing the maximum
feasible protection against risks to health from HAP.
    Moreover, as noted in our discussion of the technology review in
section IV.C of this preamble, no additional measures were identified
for reducing HAP emissions from the POTW source category. Therefore, we
propose that the 2002 standards provide an ample margin of safety to
protect public health.
    Although we are proposing to find that the 2002 standards provide
an ample margin of safety to protect public health, we are proposing
additional standards under CAA section 112(d)(6) that address HAP
emissions from collection systems and all treatment units located at
the POTW treatment plant. This is described more fully in Section
IV.C.1 below. We are proposing that POTW develop and implement
pretreatment programs to reduce organic HAP emissions from collection
systems as wastewater is conveyed from an industrial user to the POTW
treatment plant. All of the POTW identified as subject to the POTW
NESHAP already have pretreatment programs in place; therefore, no
additional emission reductions are expected. However, requiring control
of emissions from collection systems by implementing pretreatment
programs will allow POTW to limit potential future increases in
emissions since the POTW will set limits on pollutants discharged to
collection systems from industrial users. As noted above, we are
proposing that the MACT standards, prior to the implementation of these
proposed standards for collection systems, provide an ample margin of
safety to protect public health. Therefore, we are proposing that,
after the implementation of these standards for collection systems, the
rule will continue to provide an ample margin of safety to protect
public health. Consequently, it will not be necessary to conduct
another residual risk review under CAA section 112(f) for this source
category 8 years following promulgation of the new standards for
collection systems, merely due to the addition of these MACT
requirements. While our decisions on risk acceptability and ample
margin of safety are supported even in the absence of these standards
for collection systems, if we finalize the proposed requirements for
these emission sources they will further strengthen our conclusions
that risk is acceptable and the standards provide an ample margin of
safety to protect public health.
    Although we did not identify any new technologies to reduce risk
for this source category, we are specifically requesting comment on
whether there are additional control measures that may be able to
reduce risks from the source category. We request any information on
potential emission reductions of such measures, as well as the cost and
health impacts of such reductions to the extent they are known.
3. Adverse Environmental Effects
    Based on the results of our environmental risk screening
assessment, we conclude that there is not an adverse environmental
effect as a result of HAP emissions from the POTW source category. We
are proposing that it is not necessary to set a more stringent standard
to prevent, taking into consideration costs, energy, safety and other
relevant factors, an adverse environmental effect.

C. What are the results and proposed decisions based on our technology
review?

    As described in section III.C of this preamble, our technology
review focused on identifying developments in the practices, processes,
and control technologies for the POTW source category. The EPA reviewed
various information sources regarding POTW emission sources that are
currently regulated by the POTW NESHAP, which include, but are not
limited to, influent waste stream conveyance channels, bar screens,
grit chambers, grinders, pump stations, aerated feeder channels,
primary clarifiers, primary effluent channels, and primary screening
stations.
    As discussed further in sections II.C and D of this preamble, we
conducted a search of the RBLC Clearinghouse, other regulatory actions
(MACT standards, area source standards, and residual risk standards)
subsequent to promulgation of the 2002 POTW NESHAP, literature related
to research conducted for emission reductions from POTW emission
sources, and state permits. Further, we reviewed the responses to the
2015 ICR to determine the technologies and practices reported by POTW.
    We reviewed these data sources for information on add-on control
technologies, other treatment units, work practices, procedures, and
process changes or pollution prevention alternatives that were not
considered during the development of the POTW NESHAP. We also looked
for information on improvements in add-on control technology, other
treatment units, work practices, procedures, and process changes or
pollution prevention alternatives that have occurred since development
of the POTW NEHSAP. Regarding work practices or pollution prevention
alternatives, we examined data provided by the POTW in the 2015 ICR for
the POTW NESHAP related to the pretreatment programs they implement.
    As found during the development of the POTW NESHAP, there are
generally two different control options that may be used at POTW:
pretreatment programs and add-on controls (i.e., covers or covers
vented to a control device). The following sections summarize our
technology review with respect to these work practices and controls as
they can be used at industrial (Group 1) POTW and non-industrial (Group
2) POTW. (See section IV.D.2 of this preamble for a discussion of the
proposed terminology change from ``industrial'' and ``non-industrial''
POTW to ``Group 1'' and ``Group 2'' POTW.)
1. Pretreatment Requirements
    The applicability of the 2002 POTW NESHAP to a particular POTW
depends in part on whether the POTW has or is required to develop a
pretreatment program. However, we are proposing to remove having a
pretreatment program as a condition for the applicability of the NESHAP
and make it a requirement of the NESHAP. See section IV.D.1 of this
preamble for a discussion of these changes. This section describes the

inclusion of pretreatment requirements as a requirement of the rule.
    In the 2015 ICR for the POTW NESHAP, the EPA requested data related
to any pretreatment programs the POTW had developed and implemented.
All 17 of the POTW that responded to the ICR included information about
their specific pretreatment programs, and all six of the sources
subject to the POTW NESHAP have pretreatment requirements established
for all industrial wastewaters they receive. The pretreatment
requirements established by the POTW are based on the National
Pretreatment Program, which was developed under the CWA to prevent
pollutants from being introduced into a POTW that could interfere with
the operation of the POTW, or could be passed through the treatment
process and impact the use or disposal of sludge or be discharged to
surface waters (40 CFR 403.5).
    Under the Pretreatment Program, POTW subject to the requirement to
develop a pretreatment program must identify their industrial users and
control, through permits, orders, or other means, the contribution of
pollutants to the POTW in order to ensure compliance with all national
pretreatment standards and requirements. The industrial discharger must
comply with the general requirements and specific prohibitions of EPA's
regulations at 40 CFR part 403.5, categorical pretreatment standards
spelled out for industrial categories at 40 CFR Subchapter N--Effluent
Guidelines and Standards, and specific local limits that must be
developed in defined circumstances. The specific prohibitions address
characteristics of the wastewater streams and include specifications
such as flashpoint, pH, solids size (to avoid obstructions), flowrates,
and temperature of the wastewater. The specific prohibitions also
prohibit ``Pollutants which result in the presence of toxic gases,
vapors, or fumes within the POTW in a quantity that may cause acute
worker health and safety problems.'' (40 CFR 403.5(b)(7).) The
categorical pretreatment standards are specific standards established
by the EPA for certain industries. These standards vary in format and
can be concentration-based limits, mass limits, production-based
limits, best management practices, discharge prohibitions, or a
combination of these formats. There are 35 different industries with
established categorical pretreatment standards. The third component in
the pretreatment requirements consists of the local limits that must be
established by the POTW in the circumstances spelled out in the
regulations. Local limits may need to be developed to address specific
concerns of the POTW, related to the general and specific prohibitions.
In addition to ensuring that industrial users' discharges to the POTW
do not pass through the POTW and result in the violation of the POTW's
discharge permit, such limits may be necessary in the following
circumstances: to protect the POTW operations, maintain the POTW's
discharge levels, avoid sludge contamination, and ensure worker health
and safety. The local limits may be expressed as case-by-case discharge
limits, management practices, or specific prohibitions.
    In this action, we are proposing that POTW develop and implement a
pretreatment program as specified in 40 CFR part 403 (General
Pretreatment Regulations for Existing and New Sources of Pollution).
CAA section 112(n)(3) provides that the EPA may include pretreatment
requirements as a control requirement when establishing standards for
POTW under CAA section 112, stating: ``When promulgating any standard
under this section applicable to publicly owned treatment works, the
Administrator may provide for control measures that include
pretreatment of discharges causing emissions of hazardous air
pollutants and process or product substitutions or limitations that may
be effective in reducing such emissions.'' We are proposing to add
pretreatment requirements in this rulemaking because pretreatment will
reduce HAP emissions from both the collection systems and the POTW
treatment plant operations (including both primary and secondary
treatment) by limiting the quantity of HAP in the wastewater before it
is even discharged to the collection system or arrives at the POTW
treatment plant. This requirement is consistent with CAA section
112(n)(3) and will serve to reduce pollutant loading into the POTW
which will reduce emissions throughout all stages of treatment.
    Adding this pretreatment requirement to the POTW NESHAP will not
add any additional required actions or increase costs or burden for the
POTW because all of the POTW that are currently subject to this rule
have established pretreatment programs under the CWA; however, it will
ensure that pretreatment is appropriately associated to HAP reduction
requirements and remains in effect even if changes occur in CWA
regulations. The pretreatment requirements are being applied to both
industrial (Group 1) and non-industrial (Group 2) POTW for existing and
new or reconstructed POTW.
    We are requesting comment on the option of having an additional
requirement that applicable POTW specifically evaluate the volatile
organic HAP specific to each applicable industrial user because organic
HAP that volatilize readily are most likely to result in air emissions
from the water as it moves through a collection system and the POTW
treatment plant. Because the CWA's National Pretreatment Program does
not traditionally address air emissions, we understand that the
existing pretreatment requirements for each industrial user do not
necessarily reduce HAP emissions. Therefore, we are requesting comment
on requiring POTW to develop pretreatment requirements that are
specifically designed to reduce HAP emissions from POTW by requiring
the POTW to evaluate and set local limits for volatile organic HAP. We
are also requesting comment on any specific controls or operational
practices that can be required to address VOC and HAP emissions from
collection systems. Additionally, we are requesting comment on ways to
harmonize the pretreatment programs as a means to meet both CAA and CWA
requirements.
2. Industrial (Group 1) POTW
    Industrial (Group 1) POTW are those POTW that receive a wastewater
stream that is subject to control under another NESHAP and the
treatment and controls at the POTW are used to comply with the other
NESHAP requirements. We are changing the name of the subcategory in
this action, which is discussed in more detail in section IV.D of this
preamble. As discussed in section II.B.1 of this preamble, the 2002
requirements for industrial (Group 1) POTW are different for existing
and new or reconstructed sources.
    Existing industrial (Group 1) sources. At the time the 2002 NESHAP
was prepared, there were no known industrial (Group 1) POTW in
existence because the compliance dates for most of the NESHAP had not
occurred yet. As a result of this technology review, two industrial
(Group 1) POTW have been identified that are existing sources under the
rule. As required, these POTW comply with the wastewater treatment
requirements as specified in the other applicable NESHAP for which they
act as control.
    In reviewing the requirements for existing industrial (Group 1)
POTW and the situations at these sources, we have identified an issue
with the 2002 NESHAP requirements that could affect existing industrial
(Group 1) POTW,

especially considering the new requirements being proposed for existing
industrial (Group 1) and non-industrial (Group 2) POTW (see section
IV.C.3 of this preamble). The two identified existing industrial (Group
1) POTW receive wastewater from several other industrial users at their
primary treatment units, in addition to the wastewater received that is
regulated by another NESHAP. Because an existing industrial (Group 1)
POTW is currently only required to comply with the other applicable
NESHAP, the requirements under the POTW NESHAP for primary treatment
units at the POTW treatment plant do not currently apply. One of the
identified existing industrial (Group 1) POTW receives wastewater from
a pulp and paper plant, subject to 40 CFR part 63, subpart S (National
Emission Standards of Hazardous Air Pollutants from the Pulp and Paper
Industry). The subpart S wastewater is hard piped to the industrial
(Group 1) POTW and is introduced into the biological treatment unit at
the industrial (Group 1) POTW, as specified in 40 CFR 63.446(e)(2).
Because the biological treatment unit is considered secondary
treatment, there are no NESHAP requirements on the primary treatment
units at this POTW. The wastewater streams entering the primary
treatment units are not specifically regulated by another NESHAP. In
this situation, the primary treatment units are an uncontrolled HAP
emissions source even though the POTW is an industrial (Group 1) POTW
and subject to another NESHAP.
    Therefore, we are proposing to revise the requirements for an
existing industrial (Group 1) POTW so that the POTW must comply with
both the requirements for existing non-industrial (Group 2) POTW (see
section IV.C.3 of this preamble) and the other applicable NESHAP. This
proposed revision to the standards ensures that the primary treatment
units are still subject to requirements, regardless of where the other
NESHAP wastewater stream initially enters the POTW treatment plant for
treatment. We believe all of the existing industrial (Group 1) POTW can
meet the proposed requirements for existing non-industrial (Group 2)
sources, and would, therefore, incur minimal cost burden associated
with recordkeeping and reporting as described in section IV.D.5 of this
preamble.
    New or reconstructed industrial (Group 1) sources. At the time the
2002 NESHAP was prepared, we anticipated one new industrial (Group 1)
POTW would become subject to the regulation. However, during this
review we did not identify any new or reconstructed industrial (Group
1) POTW. During our review of the requirements for the existing
industrial (Group 1) POTW, we identified an issue that could affect new
industrial (Group 1) POTW. The issue is with the requirement in the
2002 rule that specifies that the source should meet the most stringent
requirements of either the other applicable NESHAP, or the requirements
for new or reconstructed non-industrial (Group 2) POTW in the POTW
NESHAP (i.e., cover primary treatment units and route emissions to a
control device; or meet 0.014 HAP fraction emitted limit). Similar to
the issue identified for existing industrial (Group 1) POTW, we found
that an industrial (Group 1) POTW could send wastewater regulated by
another NESHAP directly to a secondary treatment unit, resulting in no
overlapping requirements between the other NESHAP requirements and the
new or reconstructed source non-industrial (Group 2) POTW NESHAP
requirements, which only apply to primary treatment units. Therefore,
requiring the source to comply with the provision that is the most
stringent could be confusing, and is potentially difficult to determine
because non-POTW NESHAP requirements could apply to secondary treatment
units only and not affect primary treatment units. We considered
various other possible applicable NESHAP and the requirements in those
NESHAP and decided that similar inconsistencies could occur with other
applicable NESHAP. In some cases, it is possible that the requirement
to comply with the most stringent NESHAP could be read to allow a
source to inappropriately avoid compliance with one of the applicable
NESHAP, since the demonstration of most stringent is not clear, not
obvious, or not well defined.
    Therefore, we are proposing to remove the requirement to comply
with the most stringent NESHAP and are revising the requirement for new
or reconstructed industrial (Group 1) POTW to require the POTW to meet
the requirements of both the other applicable NESHAP, and the
requirements of the POTW NESHAP. Meeting the requirements of both the
other applicable NESHAP and the POTW NESHAP makes the rule clearer and
more consistent with the standards in other applicable NESHAP and the
POTW NESHAP.
3. Non-Industrial (Group 2) POTW
    In the 2002 regulation, non-industrial (Group 2) POTW are those
POTW that receive wastewater from industrial users but do not receive
any wastewater streams that must be controlled pursuant to another
NESHAP. In this action, we are changing this terminology as discussed
in more detail in section IV.D of this preamble. As discussed in
section II.B.4 of this preamble, requirements for non-industrial (Group
2) POTW are different for existing and new or reconstructed sources.
    Existing non-industrial (Group 2) sources. During our review, four
existing non-industrial (Group 2) POTW were identified. Treatment units
at POTW can be covered, which suppresses the volatilization of HAP,
keeping the HAP in the water and preventing emissions to the air. Also,
covered units can be vented and, if vented, emissions are either routed
to the atmosphere or a control device. The use of covers and controls
has increased since the initial development of the POTW NESHAP. For
example, in the original review for development of the 2002 rule, there
was only one POTW that had covers on all primary treatment units. Other
than grate covers (which do not control emissions and which we do not
consider to be ``covers'' as we are using that term), no other covers
were identified during the initial development of the 2002 rule. During
this review, we found two POTW subject to the POTW NESHAP that cover
all treatment units to address odor concerns. Also, more POTW now have
at least some treatment units covered. There are two POTW subject to
this rule that do not have covers on any treatment units.
    When vented to an add-on control device, the exhaust stream from
under a cover may be routed to a caustic scrubber, a carbon adsorber,
or to a secondary wastewater treatment unit such as an aeration basin
where the exhaust stream is used as feed air for biological treatment.
Add-on control devices such as caustic scrubbers and carbon adsorbers
are typically used at POTW treatment plants to control odors. While
caustic scrubbers are not expected to be effective in controlling
volatile HAP, properly designed and operated carbon adsorbers are
commonly used in other industries to control volatile organic compounds
(VOC) and HAP emissions. However, as installed at POTW to assist in
odor control, carbon adsorbers are not typically designed or operated
to provide HAP emission reduction.
    Some POTW route collected gases to biological treatment processes
to control odors, and this technique has been found to reduce emissions
of HAP. To use biological treatment as a control for HAP emissions,
treatment units must be covered, and the gases collected under the
cover must be routed to the

biological treatment unit. Based on the literature search conducted as
part of the technology review, biological treatment processes employing
activated sludge basins can achieve a VOC control efficiency greater
than 85-percent under certain conditions, and in one case, a pilot-
study biological treatment system employing biofilters was able to
achieve greater than 99-percent control of certain HAP. Outside of this
one study, the literature on biological treatment using biofilters
indicated VOC and HAP control efficiencies of between 40-percent and
83-percent. The memorandum titled Technology Review Memorandum for the
Publicly Owned Treatment Works Source Category (Technology Review
Memo), November 2016 in the docket for this action presents the
literature review and information found on biological treatment
systems.
    Detailed ICR responses regarding the use of control measures to
control HAP were received for four POTW subject to the POTW NESHAP and
eight synthetic area or area sources. For these 12 sources, all except
two sources route some portion of emissions to caustic scrubbers,
caustic scrubbers followed by carbon adsorbers (2-stage control), or
route gases to biological treatment. However, covers are not used
consistently throughout the POTW; only the two POTW subject to the POTW
NESHAP mentioned previously cover all their processes and collect all
gases and route those gases to controls. These two POTW use covers and
controls to address concerns related to odor. They do not specifically
operate the controls to reduce HAP emissions and do not have any data
specific to HAP reductions that could be achieved by the controls they
currently use. Several other POTW were found to use partial covers and
send some emissions to controls. Two other POTW subject to the POTW
NESHAP and six out of eight area sources indicated the use of add-on
control devices and several reported routing gases to biological
treatment, but not all of the HAP emissions would be captured and
controlled for these sources, because not all the treatment units are
covered at these POTW. Also, of the 12 facilities that responded to the
ICR, only three sources (all area sources operated by the City of San
Diego) claimed any HAP reduction from their odor control devices. No
indication of the VOC or HAP control efficiency for these three
facilities was available. Responses to the 2015 ICR are located in the
docket. See Information Collection and Additional Data Received for the
Publicly Owned Treatment Works Source Category Risk and Technology
Review, October 2016 located in the docket for this rulemaking.
    In this action, the EPA is soliciting comments on the effectiveness
of caustic scrubbers and carbon adsorbers to co-control HAP while
primarily functioning as odor control devices. In addition, the EPA is
requesting quantitative feedback on the effectiveness of using covers
to suppress emissions, and identification of any other key operating
parameters that may affect HAP emissions levels such as ventilation
rates or control device maintenance practices.
    In addition to an evaluation of the use of covers and controls to
reduce HAP emissions, the EPA evaluated the HAP fraction emitted up to,
but not including, secondary treatment. Data were available for two of
the non-industrial (Group 2) POTW, and their HAP fractions were 0.04
and 0.03. Additionally, since we are proposing that existing industrial
(Group 1) POTW must comply with both the other applicable NESHAP and
the HAP fraction emitted standard in the POTW NESHAP, we evaluated
available primary treatment emissions data for one of the existing
industrial (Group 1) POTW. The primary treatment units at that POTW are
not currently subject to regulation under another NESHAP; therefore,
the emissions from primary treatment units at that industrial (Group 1)
POTW are comparable to emissions from primary treatment units at the
non-industrial (Group 2) POTW. That industrial (Group 1) POTW has a HAP
fraction of 0.005. See HAP Emissions from the Publicly Owned Treatment
Works Source Category, November 2016 located in the docket for this
rulemaking.
    These HAP fractions are lower than the HAP fraction found for the
sources investigated during the development of the 2002 POTW NESHAP. At
that time, the average HAP fraction of the six POTW thought to be major
sources was 0.166. The available data for this proposal provides an
average HAP fraction of 0.0225. However, because of the limited data
and the fact that these HAP fractions are based on calculations using
data from a moment in time and do not reflect the variability in
operation, we are proposing a standard at twice the highest HAP
fraction for which we have data. Therefore, with this action, we are
proposing that existing non-industrial (Group 2) POTW must operate with
an annual rolling average HAP fraction emitted from primary treatment
units of 0.08 or less. By proposing to require that POTW achieve a HAP
fraction that is twice the maximum HAP fraction reported by ICR
respondents, we intend to address variability in wastewater influent
concentrations and in treatment operations. Moreover, as proposed the
rule is expected to allow POTW the flexibility to use various control
schemes, including the use of add-on controls such as scrubbers or
biological treatment to comply with the standard. At the same time,
because the risk analysis for allowable emissions also was assessed at
twice the level of actual emissions (see section III.A of this
preamble) the proposed standards should ensure that emissions will not
exceed the level of acceptable risk found during the risk assessment.
Also, note that this proposed standard achieves at least the same level
of protection as a standard based on a MACT floor calculation. See
Memorandum Providing Calculations for Total HAP Emissions from Publicly
Owned Treatment Works Wastewater, October 2016, located in the docket
for this rulemaking.
    We believe that the existing industrial (Group 1) and existing non-
industrial (Group 2) sources identified as subject to this proposed
rule can meet this HAP fraction emission limit. However, we request
comment and data on whether this is true for the POTW that would be
subject to this proposed standard. We are also taking comment on
whether we should provide an alternative to the 0.08 HAP fraction
emitted for existing non-industrial (Group 2) sources. One alternative
under consideration is to allow POTW to choose to cover the primary
clarifier instead of meeting the 0.08 HAP fraction emitted standard.
Data collected in the 2015 ICR indicate that primary clarifiers are the
largest emission source at the POTW, and several existing sources
already have covers on their primary clarifiers.
    We also are taking comment on a second alternative that would
require existing sources to meet the same cover and control
requirements as new sources by requiring them to cover their primary
treatment units and to route the air in the headspace from all covered
units, except the primary clarifier, to a control device via a closed
vent system. The 2002 POTW NESHAP requires a cover on primary
clarifiers, but does not require routing the air collected under the
cover to a control device. When the 2002 POTW NESHAP was developed,
data from the industry indicated that the only potential major source
with covers excluded routing air from the covered primary clarifier to
a control device. A primary clarifier is designed to operate with a
quiescent surface in order to

promote the settling of solids. Pulling air could potentially cause
turbulence on the surface of the water, thus reducing the efficiency of
the primary clarifier.
    EPA has determined that cover and control of the primary treatment
units is an expensive option, and believes that the flexibility to
develop a compliance plan to meet the HAP fraction emitted standard
will allow subject facilities more latitude to develop a compliance
approach to meet the HAP fraction standard. However, EPA is aware that
many current facilities do have a cover and control system in place to
control odors, and if those systems can be modified or operated in a
manner to control HAP emissions then this alternative might be viable
for some existing sources. More details related to the costs of covers
and controls is located in the Technology Review Memo, located in the
docket for this rulemaking.
    New or reconstructed non-industrial (Group 2) POTW. There were no
new or reconstructed non-industrial (Group 2) POTW identified during
the technology review. Also, there were no new practices or control
technologies that would warrant a change in the 2002 requirements for
new or reconstructed non-industrial (Group 2) POTW. Thus, we are not
proposing any changes in the standard for new or reconstructed non-
industrial (Group 2) POTW as a result of this technology review.

D. What other actions are we proposing?

    In addition to the proposed actions described above, we are
proposing additional revisions. We are proposing to revise the
applicability criteria to clear up confusion related to what emission
sources are included in the major source calculations and to remove the
applicability condition that affected sources must have a pretreatment
program. We are also proposing to revise the subcategory names and
definitions to further clarify the difference between them. We are
proposing revisions to the startup, shutdown, and malfunction (SSM)
provisions of the MACT rule in order to ensure that they are consistent
with the court decision in Sierra Club v. EPA, 551 F. 3d 1019 (D.C.
Cir. 2008), which vacated two provisions that exempted sources from the
requirement to comply with otherwise applicable CAA section 112(d)
emission standards during periods of SSM. We are also proposing
electronic reporting for certain records. Finally, we are proposing
various other technical corrections. Our analyses and proposed changes
related to these issues are presented below.
1. Applicability Criteria
    There are currently three criteria that a POTW must meet in order
to be subject to the POTW NESHAP: (1) You must own or operate a POTW
that includes a POTW treatment plant; (2) your POTW is a major source
of HAP emissions or any industrial (Group 1) POTW regardless of whether
or not it is a major source of HAP emissions; and (3) your POTW is
required to develop and implement a pretreatment program as defined by
40 CFR 403.8.
    The EPA is proposing to revise the first and second applicability
criteria in order to clarify the original intent of the rule by
revising 40 CFR 63.1580(a)(1) and (2) to state, ``(1) You own or
operate a POTW that is a major source of HAP emissions; or (2) you own
or operate a Group 1 POTW regardless of whether or not it is a major
source of HAP.'' See section IV.D.2 of this preamble for proposed
revisions to the subcategory names.
    We are proposing this change because during our review of the 2002
POTW NESHAP, we found several instances where a POTW might not realize
they are subject to the standards, or where the applicability criteria
could be misinterpreted, thus being read as excluding facilities that
should be covered by this NESHAP. In addition, several EPA regional
offices expressed concerns that POTW were underrepresenting their HAP
emissions and raised questions about whether emissions from equipment
comprising the collection systems should be included in those
calculations. For instance, one region discussed obtaining measurements
of high concentrations of benzene and VOC from perforated manhole
covers. Upon further inspection, the elevated readings were attributed
to an industrial user that was discharging pretreated wastewater into
the collection system for treatment at a nearby POTW. However, that
POTW was not accounting for emissions from collection systems and, to
their knowledge, had not exceeded the major source threshold. In
another region, a pump station located outside the POTW treatment plant
had potential emissions that would exceed the major source threshold.
However, because these emissions were not part of the POTW treatment
plant, they had not been previously considered when determining whether
the POTW was a major source of HAP emissions.
    The 2002 applicability criteria in 40 CFR 63.1580(a)(2) state that
it is the emissions from the entire POTW, not just the POTW treatment
plant, that must be considered when determining whether the POTW is a
major source. Further, this same provision states that any
``industrial'' (Group 1) POTW, which treats a wastewater stream which
is regulated by another NESHAP or MACT, is subject to the rule whether
or not it is a major source of HAP. The EPA recognizes that the current
wording may cause confusion regarding what emissions sources must be
included in the calculation and is proposing revisions to avoid such
confusion.
    The EPA is also proposing to revise the third applicability
criterion in order to clarify the original intent of the rule by
revising 40 CFR 63.1580(a) to state, ``You are subject to this subpart
if your publicly owned treatment works (POTW) has a design capacity to
treat at least 5 million gallons of wastewater per day and treats
wastewater from an industrial user, and either paragraph (a)(1) or
(a)(2) is true:.'' This proposed revision removes the requirement that
a POTW develop and implement a pretreatment program from the
applicability criteria, and instead clarifies the original intent of
the rule, which is to limit applicability to POTW which treat at least
5 MGD.
    The EPA also identified a potential scenario that could
inadvertently allow major source POTW to avoid applicability to the
rule based on the current third criteria. The 2002 POTW NESHAP states
that in order to be subject to the rule, the POTW must be required to
develop and implement a pretreatment program (40 CFR 63.1580(a)(3)).
During review, we identified a potential scenario where a POTW is a
major source of HAP emissions, but is not required to develop a
pretreatment program by the EPA or state pretreatment program Approval
Authority. In this scenario, the POTW might interpret the third
criterion as not applying to them. For instance, 40 CFR 403.10(e)
allows a state to assume responsibility for implementing the POTW
Pretreatment Program requirements set forth in 403.8(f) in lieu of
requiring the POTW to develop a POTW. Only five states have used their
authority under this provision (Connecticut, Vermont, Alabama,
Mississippi, and Nebraska). Similarly, other approved State Programs
which implement their State Pretreatment Program traditionally by
approving POTW pretreatment program development must also have
procedures to carry out the activities set for in 403.8(f) in the
absence of a POTW Pretreatment Program. However, the third
applicability criterion in the 2002 POTW NESHAP was not intended to
exclude POTW where states or the EPA, in the absence of a POTW approved

Pretreatment Program or a state approved pretreatment program, directly
oversee the industrial pretreatment requirements. Instead, the EPA
stated in the response to comments from the previous rulemaking \27\
that the Agency added the third applicability criterion to the final
rule to limit applicability to those POTW that are required to develop
and implement a pretreatment program in order to eliminate all POTW
with a total design flow less than 5 MGD because it was not likely that
a small POTW would have sufficient emissions to trigger major source
status. The EPA continues to believe that small POTW that do not
trigger major source status should be excluded from the requirements in
the POTW NESHAP.
---------------------------------------------------------------------------

    \27\ See National Emission Standards for Hazardous Air
Pollutants (NESHAP): Publicly Owned Treatment Works--Background
Information for Final Standards Summary of Public Comments and
Responses. EPA-453/R-99-008 October 1999.
---------------------------------------------------------------------------

    We are proposing to revise the criteria to include POTW that have a
design capacity of 5 MGD or greater and that treat wastewater from
industrial users. These are equivalent criteria for which POTW are
required to develop and implement pretreatment programs as defined in
40 CFR 403.8. However, by not stating that the ``POTW is required to
develop or implement,'' we are clarifying that any POTW that is a major
source of HAP emissions and meets the general requirements for the
development of a pretreatment program is subject to the proposed rule,
regardless of whether the state has implemented its own pretreatment
program under 40 CFR 403.10(e).
    It is not our intent that the requirements apply to small POTW that
are not a major source of HAP emissions. Therefore, we are requesting
comment on whether these proposed revisions to the applicability
criteria inadvertently include POTW that would otherwise have not been
included in a major source rule or inadvertently exclude sources that
should be covered because they are a Group 1 POTW or are a major source
of HAP emissions. Finally, we are requesting comment on whether there
is a more appropriate design capacity threshold than the 5 MGD
threshold proposed in this rulemaking.
2. Definitions of Subcategories
    The EPA is proposing to revise the names and definitions for the
subcategories identified in the POTW NESHAP in order to clear up any
confusion related to applicability of the rule. The POTW NESHAP has
historically subcategorized requirements based on whether or not a POTW
is used as a control device to comply with specific requirements in
another source category's NESHAP by classifying a POTW as either an
``industrial POTW treatment plant'' or ``non-industrial POTW treatment
plant'' (40 CFR 63.1581). The 1998 proposal described how the EPA
determined these subcategories for the POTW source category by stating
that ``the industrial POTW treatment plant subcategory would include
only those POTW treatment plants that are treating a specific regulated
industrial waste stream to allow an industrial user to comply with
another NESHAP'' (63 FR 66089). We further explained that any POTW not
in the industrial POTW treatment plant subcategory would be classified
as a non-industrial POTW treatment plant, which accepts waste from
industrial users whose waste is not specifically regulated under
another NESHAP. While the intent of the subcategorization was explained
in the 1998 proposal and the terms are defined in the rule (in 40 CFR
63.1595), there is a potential for confusion related to applicability
under the subcategories because the terms ``industrial'' and ``non-
industrial'' have common, everyday meanings that are not exactly
aligned with how those terms are defined in the rule. For example, a
person might incorrectly assume that the term ``industrial POTW''
includes any POTW that accepts waste from an industrial user, even if
the industrial user is not subject to another NESHAP, and that a ``non-
industrial POTW'' is one that does not take any waste from any
industrial users.
    To clear up this confusion, we are proposing to change the names
and definitions of the subcategories in the POTW source category. A
``Group 1 POTW treatment plant'' is one that accepts a waste stream(s)
regulated under another NESHAP from an industrial user for treatment.
In this instance, the POTW acts as the control mechanism by which the
industrial user is able to comply with the specific requirements for
that waste stream in the other NESHAP. For example, a pulp mill may
choose to send a waste stream regulated by 40 CFR part 63, subpart S
(Pulp and Paper Industry NESHAP) to a local POTW for treatment in lieu
of constructing an onsite wastewater treatment facility to comply with
the requirements of subpart S. In this example, the POTW is in a
contractual agreement with the pulp mill that the POTW will meet the
specific requirements for that waste stream and becomes subject to the
Pulp and Paper Industry NESHAP in addition to the POTW NESHAP. A Group
1 POTW treatment plant does not have to have HAP emissions in excess of
the major source threshold but is instead considered subject to this
proposed rule because it is also subject to requirements in another
NESHAP. If the Group 1 POTW treatment plant accepts multiple waste
streams that are regulated under multiple NESHAP, we are proposing that
the POTW would meet the requirements of each appropriate NESHAP for
each individual waste stream.
    A ``Group 2 POTW treatment plant'' is one that accepts a waste
stream(s) that is not specifically regulated by another NESHAP or one
that accepts wastewater from an industrial facility that complies with
the specific wastewater requirements in their applicable NESHAP prior
to discharging the wastewater to the POTW collection system. These
waste streams can come from an industrial or commercial source. For
example, a chemical plant sends a waste stream to a POTW that is not
regulated by any of the chemical manufacturing source categories for
treatment as a permitted discharge through the POTW's pretreatment
program. In most cases, these waste streams are pretreated at the
industrial facility in order to meet specific water quality
requirements issued by the POTW through a Significant Industrial User
(SIU) permit. Pretreatment programs are discussed in section IV.C.1 of
this preamble.
    The EPA is proposing the ``Group 1'' and ``Group 2'' names rather
than a new pair of descriptive names because (1) the non-descriptive
names ``Group 1'' and ``Group 2'' will alert persons to the fact that
they need to look to the specific definitions of the subcategories in
the rule, and (2) we could not identify any descriptive names that did
not create the potential for confusion similar to the current
``industrial'' and ``non-industrial'' labels. The EPA requests ideas
for descriptive names for the two subcategories that would not create a
potential for confusion.
3. Startup, Shutdown, and Malfunction
    In its 2008 decision in Sierra Club v. EPA, 551 F.3d 1019 (D.C.
Cir. 2008), the United States Court of Appeals for the District of
Columbia Circuit vacated portions of two provisions in the EPA's CAA
section 112 regulations governing the emissions of HAP during periods
of SSM. Specifically, the Court vacated the SSM exemption contained in
40 CFR 63.6(f)(1) and 40 CFR 63.6(h)(1), holding that under section
302(k) of the CAA, emissions standards or limitations must

be continuous in nature and that the SSM exemption violates the CAA's
requirement that some CAA section 112 standards apply continuously.
    We are proposing the elimination of the SSM exemption in this rule.
Consistent with Sierra Club v. EPA, we are proposing standards in this
rule that apply at all times. We are also proposing several revisions
to Table 1 to Subpart VVV of Part 63 (the General Provisions
Applicability Table) as is explained in more detail below. For example,
we are proposing to eliminate the incorporation of the General
Provisions' requirement that the source develop an SSM plan. We also
are proposing to eliminate and revise certain recordkeeping and
reporting requirements related to the SSM exemption as further
described below.
    The EPA has attempted to ensure that the provisions we are
proposing to eliminate are inappropriate, unnecessary, or redundant in
the absence of the SSM exemption. We are specifically seeking comment
on whether we have successfully done so.
    In developing the standards in this rule, the EPA has taken into
account startup and shutdown periods and has not proposed alternate
standards for those periods. Periods of startup and shutdown at POTW
are highly infrequent events. At all times, a plant subject to 40 CFR
part 63, subpart VVV must comply with the pretreatment requirements and
either the cover and closed vent system standard or the HAP fraction
emissions standard.
    For pretreatment requirements, startup and shutdown at the POTW do
not impact the effect of pretreatment requirements, because these
require POTW to apply pretreatment standards on the industrial users.
The industrial users meet these standards before the wastewater enters
the collection system of the POTW and so those industrial users'
ability to meet the pretreatment requirements is not dependent on the
operational status of the POTW.
    For compliance using covers and closed vent systems routed to a
control device, startup and shutdown of the POTW does not affect
performance of the control device. The control system can and must be
operated when wastewater first enters the system. In the unlikely event
of shutdown of the POTW, the control system must be operated until the
final wastewaters are treated. Because the physical and chemical
characteristic of the gases in the closed vent system are not
sufficiently different during startup and shutdown, the emission
control system will achieve the same level of emission control that it
achieves during normal operation. Therefore, there is no need for an
alternative standard during startup and shutdown that is different from
the standards for normal operation.
    It is possible that control devices (e.g., flares, carbon
absorbers, or scrubbers) that receive emissions through the closed vent
systems could have startup and shutdown events. This equipment must
meet the requirements of 40 CFR part 63, subpart DD (because DD is
incorporated by reference into subpart VVV). Subpart DD requires that
control devices are operating to fully control emissions when emissions
are routed to them, as specified in 40 CFR 63.693 of subpart DD, except
for a limited number of hours per year for routine maintenance for
control devices controlling tank emissions (40 CFR 63.693(b)(3)).
    For compliance using the alternative HAP fraction emissions
standard, compliance may be achieved by a combination of a cover and
closed vent system to a control device, a biological treatment phase,
pretreatment, or modifications to the wastewater treatment process. The
covers, closed vents, and the range of potential control devices would
all be available throughout startup and shutdown of the POTW.
Therefore, we do not expect there to be any significant difference in
the emissions due to a startup or shutdown. In addition, compliance
with the HAP fraction emissions standard is demonstrated based on a 12-
month rolling average. Because the averaging period is annual, any
increases in the HAP fraction emitted that do occur during startup or
shutdown periods (which are short), can easily be balanced by the
longer periods of normal operation and lower HAP fraction emitted
during the rest of the averaging period.
    Periods of startup, normal operations, and shutdown are all
predictable and routine aspects of a source's operations. Malfunctions,
in contrast, are neither predictable nor routine. Instead, they are, by
definition, sudden, infrequent and not reasonably preventable failures
of emissions control, process, or monitoring equipment. (See 40 CFR
63.2, definition of Malfunction). The EPA interprets CAA section 112 as
not requiring emissions that occur during periods of malfunction to be
factored into development of CAA section 112 standards. Under CAA
section 112, emissions standards for new sources must be no less
stringent than the level ``achieved'' by the best controlled similar
source and for existing sources generally must be no less stringent
than the average emission limitation ``achieved'' by the best
performing 12 percent of sources in the category. There is nothing in
CAA section 112 that directs the Agency to consider malfunctions in
determining the level ``achieved'' by the best performing sources when
setting emission standards. As the District of Columbia Circuit Court
has recognized, the phrase ``average emissions limitation achieved by
the best performing 12 percent of'' sources ``says nothing about how
the performance of the best units is to be calculated.'' Nat'l Ass'n of
Clean Water Agencies v. EPA, 734 F.3d 1115, 1141 (D.C. Cir. 2013).
While the EPA accounts for variability in setting emissions standards,
nothing in CAA section 112 requires the Agency to consider malfunctions
as part of that analysis. A malfunction should not be treated in the
same manner as the type of variation in performance that occurs during
routine operations of a source. A malfunction is a failure of the
source to perform in a ``normal or usual manner'' and no statutory
language compels the EPA to consider such events in setting CAA section
112 standards.
    Further, accounting for malfunctions in setting emission standards
would be difficult, if not impossible, given the myriad different types
of malfunctions that can occur across all sources in the category and
given the difficulties associated with predicting or accounting for the
frequency, degree, and duration of various malfunctions that might
occur. As such, the performance of units that are malfunctioning is not
``reasonably'' foreseeable. See, e.g., Sierra Club v. EPA, 167 F.3d
658, 662 (D.C. Cir. 1999) (``The EPA typically has wide latitude in
determining the extent of data-gathering necessary to solve a problem.
We generally defer to an agency's decision to proceed on the basis of
imperfect scientific information, rather than to `invest the resources
to conduct the perfect study.' '') See also, Weyerhaeuser v Costle, 590
F.2d 1011, 1058 (D.C. Cir. 1978) (``In the nature of things, no general
limit, individual permit, or even any upset provision can anticipate
all upset situations. After a certain point, the transgression of
regulatory limits caused by `uncontrollable acts of third parties,'
such as strikes, sabotage, operator intoxication or insanity, and a
variety of other eventualities, must be a matter for the administrative
exercise of case-by-case enforcement discretion, not for specification
in advance by regulation.''). In addition, emissions during a
malfunction event can be significantly higher than emissions at any
other time of source operation. For example, if an air pollution
control

device with 99-percent removal goes off-line as a result of a
malfunction (as might happen if, for example, the bags in a baghouse
catch fire) and the emission unit is a steady state type unit that
would take days to shut down, the source would go from 99-percent
control to zero control until the control device was repaired. The
source's emissions during the malfunction would be 100 times higher
than during normal operations. As such, the emissions over a 4-day
malfunction period would exceed the annual emissions of the source
during normal operations. As this example illustrates, accounting for
malfunctions could lead to standards that are not reflective of (and
significantly less stringent than) levels that are achieved by a well-
performing non-malfunctioning source. It is reasonable to interpret CAA
section 112 to avoid such a result. The EPA's approach to malfunctions
is consistent with CAA section 112 and is a reasonable interpretation
of the statute.
    Similar to startup and shutdown events, malfunctions of the POTW do
not impact the effect of pretreatment requirements, because these
require POTW to apply pretreatment standards on the industrial users.
The industrial users meet these standards before the wastewater enters
the collection system of the POTW.
    In the case of a POTW that uses covers, closed vent systems, and
control devices, the covers and closed vents are typically constructed
without moving parts and are frequently permanent structures made of
concrete. While malfunctions are theoretically possible, the EPA found
no information from affected facilities that malfunctions have actually
happened in such systems.
    The control devices used to comply with the standards in 40 CFR
part 63, subpart VVV are subject to the control device standards in 40
CFR part 63, subpart DD (because subpart DD is incorporated by
reference into subpart VVV). A malfunction of control devices that are
subject to subpart DD that results in a failure to meet a standard
would be subject to the excess emissions recordkeeping and reporting
requirements for the relevant device under subpart DD.
    For POTW that are complying with the HAP fraction emissions
alternative standard, the standard is an annual rolling average of the
HAP fraction emitted. A malfunction event at a facility that is
properly maintained and operated is likely to result in only a small
and short-term increase in emissions that is unlikely to cause an
exceedance of the annual standard. In the event that a malfunction
causes an exceedance, the facility would report the nature of the
malfunction in the excess emission report.
    In the unlikely event that a source fails to comply with the
applicable CAA section 112(d) standards as a result of a malfunction
event, the EPA would determine an appropriate response based on, among
other things, the good faith efforts of the source to minimize
emissions during malfunction periods, including preventative and
corrective actions, as well as root cause analyses to ascertain and
rectify excess emissions. The EPA would also consider whether the
source's failure to comply with the CAA section 112(d) standard was, in
fact, sudden, infrequent, not reasonably preventable and was not
instead caused in part by poor maintenance or careless operation (see
40 CFR 63.2, definition of Malfunction).
    If the EPA determines in a particular case that an enforcement
action against a source for violation of an emission standard is
warranted, the source can raise any and all defenses in that
enforcement action and the Federal District Court will determine what,
if any, relief is appropriate. The same is true for citizen enforcement
actions. Similarly, the presiding officer in an administrative
proceeding can consider any defense raised and determine whether
administrative penalties are appropriate.
    In summary, the EPA interpretation of the CAA and, in particular,
CAA section 112 is reasonable and encourages practices that will avoid
malfunctions. Administrative and judicial procedures for addressing
exceedances of the standards fully recognize that violations may occur
despite good faith efforts to comply and can accommodate those
situations.
    The EPA is proposing changes to the SSM provisions of 40 CFR part
63, subpart VVV to comport with the Sierra Club court ruling and
harmonize with certain provisions of 40 CFR part 63, subpart DD.
Subpart VVV incorporates some requirements of subpart DD by reference.
In 2015 (see 80 FR 14248), the SSM provisions of subpart DD were
revised. The changes proposed here for the SSM provisions in subpart
VVV are congruent to the changes already promulgated under subpart DD.
This section describes how we propose to revise subpart VVV to
harmonize with the SSM changes that have already been promulgated in
subpart DD.
a. 40 CFR 63.1583 and 63.1586 General Duty
    We are proposing to revise the General Provisions Table, Table 1 to
Subpart VVV of part 63, (hereafter referred to as Table 1) entry for 40
CFR 63.6(e)(1)(i) by changing the ``yes'' in column 2 to a ``no.''
Section 63.6(e)(1)(i) describes the general duty to minimize emissions.
Some of the language in that section is no longer necessary or
appropriate in light of the elimination of the SSM exemption. We are
proposing instead to add general duty regulatory text at 40 CFR
63.1583(d) and 63.1586(e) that reflects the general duty to minimize
emissions while eliminating the reference to periods covered by an SSM
exemption in Table 1. The current language in 40 CFR 63.6(e)(1)(i)
characterizes what the general duty entails during periods of SSM. With
the elimination of the SSM exemption, there is no need to differentiate
between normal operations, startup and shutdown, and malfunction events
in describing the general duty. Therefore, the language the EPA is
proposing for 40 CFR 63.1583(d) and 63.1586(e) does not include that
language from 40 CFR 63.6(e)(1).
    We are also proposing to revise Table 1 by adding an entry for 40
CFR 63.6(e)(1)(ii) and designating in column 2 that it does not apply
with a ``no.'' Section 63.6(e)(1)(ii) imposes requirements that are not
necessary with the elimination of the SSM exemption or are redundant
with the general duty requirement being added at 40 CFR 63.1583(d) and
63.1586(e).
b. SSM Plan
    We are proposing to revise Table 1 by adding an entry for 40 CFR
63.6(e)(3) and designating that it does not apply. Generally, these
paragraphs require development of an SSM plan and specify SSM
recordkeeping and reporting requirements related to the SSM plan. As
noted, the EPA is proposing to remove the SSM exemptions. Therefore,
affected units will be subject to an emission standard during such
events. The applicability of a standard during such events will ensure
that sources have ample incentive to plan for and achieve compliance
and thus the SSM plan requirements are no longer necessary.
c. Compliance With Standards
    We are proposing to revise table 1 by adding an entry for 40 CFR
63.6(f)(1) and designating that it does not apply. The current language
of 40 CFR 63.6(f)(1) exempts sources from non-opacity standards during
periods of SSM. As discussed above, the court in Sierra Club vacated
the exemptions contained in this provision and held that the CAA
requires that some CAA section 112 standards apply

continuously. Consistent with Sierra Club, the EPA is proposing to
revise standards in this rule to apply at all times.
    We are proposing to leave unchanged the Table 1 entry for 40 CFR
63.6(h) because the existing rule indicated that opacity standards are
not applicable. The current language of 40 CFR 63.6(h)(1) exempts
sources from opacity standards during periods of SSM. Generally, POTW
do not have visible emissions.
d. 40 CFR 63.1590 Performance Testing
    We are proposing to revise the Table 1 entry for 40 CFR 63.7(e)(1)
by changing the ``yes'' in column 2 to a ``no.'' Section 63.7(e)(1)
describes performance testing requirements. The EPA is instead
proposing to revise the language used to incorporate the performance
testing requirements at 40 CFR 63.694, the performance testing
provisions for control devices in 40 CFR part 63, subpart DD. The
performance testing requirements in subpart DD differ from the General
Provisions performance testing provisions in several respects. The
performance testing provisions in 40 CFR 63.694(l) of subpart DD
(incorporated by reference) provide that performance tests be based on
representative performance (i.e., performance based on normal operating
conditions) and exclude periods of startup and shutdown unless
specified by the Administrator. And as in 40 CFR 63.7(e)(1),
performance tests conducted under this subpart should not be conducted
during malfunctions because conditions during malfunctions are often
not representative of normal operating conditions. The EPA is proposing
to revise the language incorporating those sections of subpart DD that
require the owner or operator to record the process information that is
necessary to document operating conditions during the test and include
in such record an explanation to support that such conditions represent
normal operation. Section 63.7(e) requires that the owner or operator
make available to the Administrator such records ``as may be necessary
to determine the condition of the performance test'' available to the
Administrator upon request, but does not specifically require the
information to be recorded. The regulatory text the EPA is proposing to
incorporate builds on that requirement and makes explicit the
requirement to record the information.
e. Monitoring
    We are proposing to revise the table 1 entry for 40 CFR 63.8 by
adding specific table entries for 63.8(c)(1)(i) and (iii) and
indicating ``no'' in column 2. The cross-references to the general duty
and SSM plan requirements in those subparagraphs are not necessary in
light of other requirements of 40 CFR 63.8 that require good air
pollution control practices (40 CFR 63.8(c)(1)) and that set out the
requirements of a quality control program for monitoring equipment (40
CFR 63.8(d)).
    We are proposing to revise Table 1 by adding an entry for 40 CFR
63.8(d)(3) and indicating ``no'' in column 2. The final sentence in 40
CFR 63.8(d)(3) refers to the General Provisions' SSM plan requirement
which is no longer applicable. The EPA is proposing to add language to
Table 1 that is identical to 40 CFR 63.8(d)(3), except that the final
sentence is replaced with the following sentence: ``The program of
corrective action should be included in the plan required under Sec.
63.8(d)(2).''
f. 40 CFR 63.1589 Recordkeeping
    We are proposing to revise the Table 1 entry for 40 CFR
63.10(b)(2)(i) by changing the ``yes'' in column 2 to a ``no.'' Section
63.10(b)(2)(i) describes the recordkeeping requirements during startup
and shutdown. These recording provisions are no longer necessary
because the EPA is proposing that recordkeeping and reporting
applicable to normal operations will apply to startup and shutdown. In
the absence of special provisions applicable to startup and shutdown,
such as a startup and shutdown plan, there is no reason to retain
additional recordkeeping for startup and shutdown periods.
    We are proposing to revise Table 1 to add an entry for 40 CFR
63.10(b)(2)(ii) and indicating ``no'' in column 2. Section
63.10(b)(2)(ii) describes the recordkeeping requirements during a
malfunction. The EPA is proposing that the requirements of 40 CFR
63.696(h) and 40 CFR 63.1589(d) be the applicable recordkeeping
requirements. The regulatory text we are proposing to make applicable
differs from the General Provisions it is replacing in that the General
Provisions requires the creation and retention of a record of the
occurrence and duration of each malfunction of process, air pollution
control, and monitoring equipment. The EPA is proposing that 40 CFR
63.696(h) and 40 CFR 63.1589(d) apply to any failure to meet an
applicable standard and is requiring that the source record the date,
time, and duration of the failure rather than the ``occurrence.'' The
requirements under 40 CFR 63.696(h) and 40 CFR 63.1589(d) also provide
that sources keep records that include a list of the affected source or
equipment and actions taken to minimize emissions, an estimate of the
quantity of each regulated pollutant emitted over the standard for
which the source failed to meet the standard, and a description of the
method used to estimate the emissions. Examples of such methods would
include product-loss calculations, mass balance calculations,
measurements when available, or engineering judgment based on known
process parameters. The EPA is proposing to require that sources keep
records of this information to ensure that there is adequate
information to allow the EPA to determine the severity of any failure
to meet a standard, and to provide data that may document how the
source met the general duty to minimize emissions when the source has
failed to meet an applicable standard.
    We are proposing to revise the General Provisions table (Table 1
entry for 40 CFR 63.10(b)(2)(iv) by changing the ``yes'' in column 2 to
a ``no.'' When applicable, the provision requires sources to record
actions taken during SSM events when actions were inconsistent with
their SSM plan. The requirement is no longer appropriate because SSM
plans will no longer be required. The requirement previously applicable
under 40 CFR 63.10(b)(2)(iv)(B) to record actions to minimize emissions
and record corrective actions is now applicable as a record required by
40 CFR 63.696(h) and 40 CFR 63.1589(d).
    We are proposing to revise the General Provisions Table 1 entry for
40 CFR 63.10(b)(2)(v) by adding an entry and indicating ``no'' in
column 2. When applicable, the provision requires sources to record
actions taken during SSM events to show that actions taken were
consistent with their SSM plan. The requirement is no longer
appropriate because SSM plans will no longer be required.
    We are proposing to revise Table 1 by adding an entry for 40 CFR
63.10(c)(15) and indicating ``no'' in column 2. The EPA is proposing
that 40 CFR 63.10(c)(15) no longer apply. When applicable, the
provision allows an owner or operator to use the affected source's
startup, shutdown, and malfunction plan or records kept to satisfy the
recordkeeping requirements of the startup, shutdown, and malfunction
plan specified in 40 CFR 63.6(e), to also satisfy the requirements of
40 CFR 63.10(c)(10) through (12). The EPA is proposing to eliminate
this

requirement because SSM plans would no longer be required, and
therefore 40 CFR 63.10(c)(15) no longer serves any useful purpose for
affected units.
g. 40 CFR 63.1590 Reporting
    We are proposing to revise the Table 1 entry for 40 CFR 63.10(d)(5)
by adding an entry and indicating ``no'' in column 2. Section
63.10(d)(5) describes the reporting requirements for startups,
shutdowns, and malfunctions. Rather than rely on the General Provisions
reporting requirement, the EPA is proposing that the existing
incorporation in 40 CFR 63.693 of subpart DD adequately provides for
reporting of a failure to meet a standard when control devices are
being used and 40 CFR 63.1590(a) when there is a failure to meet the
standard when other compliance methods are used. Section 63.693
requires that sources that fail to meet an applicable standard at any
time must report the information concerning such events in the semi-
annual report required for affected facilities under 40 CFR
63.697(b)(3) and (b)(4). The current provisions in subpart DD that we
are proposing, which apply when control devices are used as the
compliance measure, state that the report must contain the number,
date, time, duration, and the cause of such events (including unknown
cause, if applicable), a list of the affected source or equipment, an
estimate of the quantity of each regulated pollutant emitted over any
emission limit, and a description of the method used to estimate the
emissions. We are proposing a similar report in 40 CFR 63.1590(a) that
contains the same reporting elements, but applies when another
compliance measure other than a control device, is used. This report is
required annually.
    Examples of such methods would include product-loss calculations,
mass balance calculations, measurements when available, or engineering
judgment based on known process parameters. The EPA is proposing this
requirement to ensure that there is adequate information to determine
compliance, to allow the EPA to determine the severity of the failure
to meet an applicable standard, and to provide data that may document
how the source met the general duty to minimize emissions during a
failure to meet an applicable standard.
    We will no longer require owners or operators to determine whether
actions taken to correct a malfunction are consistent with an SSM plan,
because plans would no longer be required. The proposed amendments,
therefore, eliminate the cross reference to 40 CFR 63.10(d)(5)(i) that
contains the description of the previously required SSM report format
and submittal schedule from this section. These specifications are no
longer necessary because the events will be reported in otherwise
required reports with similar format and submittal requirements.
    We are proposing to revise the Table 1 entry for 40 CFR
63.10(d)(5)(ii) by adding an entry and indicating ``no'' in column 2.
Section 63.10(d)(5)(ii) describes an immediate report for SSM when a
source failed to meet an applicable standard but did not follow the SSM
plan. We will no longer require owners and operators to report when
actions taken during a SSM were not consistent with an SSM plan,
because plans would no longer be required.
    We are proposing to revise the Table 1 entry for 40 CFR
63.10(d)(5)(i) by changing the ``yes'' in column 2 to ``no.'' Section
63.10(d)(5)(i) describes the reporting requirements for SSM when a
source failed to meet an applicable standard and was subject to 40 CFR
63.6(e)(3). To replace the General Provisions requirement, the EPA is
proposing to revise reporting requirements in 40 CFR 63.1590(f) and
(g), which referred to SSM plans. The revised language for 40 CFR
63.1590(f) and (g) is proposed to be in 63.1590(b) and (f)
respectively. Also, a report has been added at 63.1590(a)(4) for each
failure to meet an applicable standard at an affected source, the owner
or operator must report the failure and event to the Administrator in
an annual Compliance Report. The report must contain the date, time,
duration, and the cause of each event (including unknown cause, if
applicable), and a sum of the number of events in the reporting period.
The report must list for each event the affected source or equipment,
an estimate of the quantity of each regulated pollutant emitted over
any emission limit, and a description of the method used to estimate
the emissions.
    Examples of such methods would include product-loss calculations,
mass balance calculations, measurements when available, or engineering
judgment based on known process parameters. The EPA is proposing this
requirement to ensure that there is adequate information to determine
compliance, to allow the EPA to determine the severity of the failure
to meet an applicable standard, and to provide data that may document
how the source met the general duty to minimize emissions during a
failure to meet an applicable standard.
    We are proposing to revise Table 1 by adding an entry for 40 CFR
63.10(d)(5)(ii) and indicating ``no'' in column 2. Section
63.10(d)(5)(ii) describes an immediate report for SSM when a source
failed to meet an applicable standard, was subject to 40 CFR
63.6(e)(3), but did not follow the plan. We will no longer require
owners or operators to report when actions taken during SSM were not
consistent with an SSM plan, because plans would no longer be required.
4. Electronic Reporting
    Through this proposal, the EPA is proposing that owners and
operators of POTW treatment plants submit electronic copies of required
performance test reports and annual reports through the EPA's Central
Data Exchange (CDX) using the Compliance and Emissions Data Reporting
Interface (CEDRI). The EPA believes that the electronic submittal of
the reports addressed in this proposed rulemaking will increase the
usefulness of the data contained in those reports, is in keeping with
current trends in data availability, will further assist in the
protection of public health and the environment, and will ultimately
result in less burden on the regulated community. Under current
requirements, paper reports are often stored in filing cabinets or
boxes, which make the reports more difficult to obtain and use for data
analysis and sharing. Electronic storage of such reports would make
data more accessible for review, analyses, and sharing. Electronic
reporting can also eliminate paper-based, manual processes, thereby
saving time and resources, simplifying data entry, eliminating
redundancies, minimizing data reporting errors, and providing data
quickly and accurately to the affected facilities, air agencies, the
EPA, and the public.
    In 2011, in response to Executive Order 13563, the EPA developed a
plan \28\ to periodically review its regulations to determine if they
should be modified, streamlined, expanded, or repealed in an effort to
make regulations more effective and less burdensome. The plan includes
replacing outdated paper reporting with electronic reporting. In
keeping with this plan and the White House's Digital Government
Strategy,\29\ in 2013 the EPA issued an Agency-wide policy specifying
that new regulations will require reports to be electronic to the
maximum extent

possible. By requiring electronic submission of specified reports in
this proposed rule, the EPA is taking steps to implement this policy.
---------------------------------------------------------------------------

    \28\ EPA's Final Plan for Periodic Retrospective Reviews, August
2011. Available at: https://www.epa.gov/sites/production/files/2015-09/documents/eparetroreviewplan-aug2011_0.pdf.
    \29\ Digital Government: Building a 21st Century Platform to
Better Serve the American People, May 2012. Available at: https://www.whitehouse.gov/sites/default/files/omb/egov/digital-government/digital-government-strategy.pdf.
---------------------------------------------------------------------------

    The EPA Web site that stores the submitted electronic data,
WebFIRE, will be easily accessible to everyone and will provide a user-
friendly interface that any stakeholder could access. By making data
readily available, electronic reporting increases the amount of data
that can be used for many purposes. One example is the development of
emissions factors. An emissions factor is a representative value that
attempts to relate the quantity of a pollutant released to the
atmosphere with an activity associated with the release of that
pollutant (e.g., kilograms of particulate emitted per megagram of coal
burned). Such factors facilitate the estimation of emissions from
various sources of air pollution and are an important tool in
developing emissions inventories, which in turn are the basis for
numerous efforts, including trends analysis, regional and local scale
air quality modeling, regulatory impact assessments, and human exposure
modeling. Emissions factors are also widely used in regulatory
applicability determinations and in permitting decisions.
    The EPA has received feedback from stakeholders asserting that many
of the EPA's emissions factors are outdated or not representative of a
particular industry emission source. While the EPA believes that the
emissions factors are suitable for their intended purpose, we recognize
that the quality of emissions factors varies based on the extent and
quality of underlying data. We also recognize that emissions profiles
on different pieces of equipment can change over time due to a number
of factors (fuel changes, equipment improvements, industry work
practices), and it is important for emissions factors to be updated to
keep up with these changes. The EPA is currently pursuing emissions
factor development improvements that include procedures to incorporate
the source test data that we are proposing be submitted electronically.
By requiring the electronic submission of the reports identified in
this proposed action, the EPA would be able to access and use the
submitted data to update emissions factors more quickly and
efficiently, creating factors that are characteristic of what is
currently representative of the relevant industry sector. Likewise, an
increase in the number of test reports used to develop the emissions
factors will provide more confidence that the factor is of higher
quality and representative of the whole industry sector.
    Additionally, by making the records, data, and reports addressed in
this proposed rulemaking readily available, the EPA, the regulated
community, and the public will benefit when the EPA conducts its CAA-
required technology and risk-based reviews. As a result of having
performance test reports and air emission reports readily accessible,
our ability to carry out comprehensive reviews will be increased and
achieved within a shorter period of time. These data will provide
useful information on control efficiencies being achieved and
maintained in practice within a source category and across source
categories for regulated sources and pollutants. These reports can also
be used to inform the technology-review process by providing
information on improvements to add-on control technology and new
control technology.
    Under an electronic reporting system, the EPA's Office of Air
Quality Planning and Standards (OAQPS) would have air emissions and
performance test data in hand; OAQPS would not have to collect these
data from the EPA Regional Offices or from delegated air agencies or
industry sources in cases where these reports are not submitted to the
EPA Regional Offices. Thus, we anticipate fewer or less substantial
ICRs in conjunction with prospective CAA-required technology and risk-
based reviews may be needed. We expect this to result in a decrease in
time spent by industry to respond to data collection requests. We also
expect the ICRs to contain less extensive stack testing provisions, as
we will already have stack test data electronically. Reduced testing
requirements would be a cost savings to industry. The EPA should also
be able to conduct these required reviews more quickly, as OAQPS will
not have to include the ICR collection time in the process or spend
time collecting reports from the EPA Regional Offices. While the
regulated community may benefit from a reduced burden of ICRs, the
general public benefits from the Agency's ability to provide these
required reviews more quickly, resulting in increased public health and
environmental protection.
    Electronic reporting could minimize submission of unnecessary or
duplicative reports in cases where facilities report to multiple
government agencies and the agencies opt to rely on the EPA's
electronic reporting system to view report submissions. Where air
agencies continue to require a paper copy of these reports and will
accept a hard copy of the electronic report, facilities will have the
option to print paper copies of the electronic reporting forms to
submit to the air agencies, and, thus, minimize the time spent
reporting to multiple agencies. Additionally, maintenance and storage
costs associated with retaining paper records could likewise be
minimized by replacing those records with electronic records of
electronically submitted data and reports.
    Air agencies could benefit from more streamlined and automated
review of the electronically submitted data. For example, because the
performance test data would be readily-available in a standard
electronic format, air agencies would be able to review reports and
data electronically rather than having to conduct a review of the
reports and data manually. Having reports and associated data in
electronic format will facilitate review through the use of software
``search'' options, as well as the downloading and analyzing of data in
spreadsheet format. Additionally, air agencies would benefit from the
reported data being accessible to them through the EPA's electronic
reporting system wherever and whenever they want or need access (as
long as they have access to the Internet). The ability to access and
review air emission report information electronically will assist air
agencies to more quickly and accurately determine compliance with the
applicable regulations, potentially allowing a faster response to
violations which could minimize harmful air emissions. This benefits
both air agencies and the general public.
    The proposed electronic reporting of data is consistent with
electronic data trends (e.g., electronic banking and income tax
filing). Electronic reporting of environmental data is already common
practice in many media offices at the EPA. The changes being proposed
in this rulemaking are needed to continue the EPA's transition to
electronic reporting.
5. Reporting
    In addition to the changes made to reporting to address the court
decision in Sierra Club v. EPA, 551 F. 3d 1019 (D.C. Cir. 2008) on SSM
requirements described in section IV.D.3 of this preamble, we are
proposing several other changes to the reporting requirements. We are
proposing to add an annual report; to remove language that is redundant
with 40 CFR part 63, subpart A, general provision requirements; and to
not delegate the approval of the Inspection and Monitoring Plan. We are
also asking for comment on requiring specific test methods and modeling
procedures instead of allowing the POTW to specify

their methods in the Inspection and Monitoring Plan. Our analyses and
proposed changes related to these issues are presented below.
    Annual Report. EPA is proposing to add a requirement to submit an
annual report. The proposed contents for the annual report include
general identification information for the POTW; information on the
monthly HAP fraction emitted calculation results; and cover inspection
results for new or reconstructed POTW, depending on which compliance
method the POTW selects. Also, we are proposing to include a
requirement to report information about periods when the POTW has a
failure to meet a standard as part of the annual report. The failure to
meet report is discussed in more detail in section IV.D.3.g. We are
also proposing that the annual report be submitted electronically. The
rationale and benefits of having this report submitted electronically
is discussed in section IV.D.4 of this preamble.
    EPA is proposing the annual report to address the changes in SSM
requirements as described in section IV.D.3.g, to receive timely
compliance information from the POTW, and as a method to collect
additional information to enhance our ability to carry out
comprehensive reviews within a shorter period of time. These data will
provide useful information on HAP fraction emissions and inspection
results across regulated POTW. These reports can be used to inform the
technology-review process, reduce the need for complex ICRs, and could
result in a decrease in time spent by industry in responding to data
collection requests.
    For existing POTW, it is proposed that the initial annual report
will cover the first year after the compliance date, which is one year
after promulgation, and 3 months are proposed to allow time for the
POTW to compile and prepare the information for submittal. Therefore,
the first annual report for existing POTW must be submitted to the
Administrator 27 months after the promulgation of this rulemaking. For
new POTW, the initial annual report must be submitted 15 months after
the POTW becomes subject to the rule. The initial annual report must
cover the 12-month period following the day the new POTW becomes
subject, with 3 months proposed to allow the POTW time to compile and
prepare the submittal. All subsequent annual reports, for new or
existing POTW, must be submitted annually thereafter.
    General Provision requirements. EPA is proposing to revise the
reporting and notification requirements in 40 CFR 63.1590 and 63.1591
by removing those requirements that are redundant to requirements that
are included in the General Provisions (40 CFR 63, subpart A) and
marked as applicable in Table 1 of the POTW NESHAP. Specifically, much
of the language in the 2002 POTW NESHAP requirements in 40 CFR
63.1590(a), (b), (d), and 40 CFR 63.1591(a) and (b) is the same or very
similar to the requirements in the general provisions at 40 CFR
63.9(h)(2), (h)(3), (a)(4), (a)(4), and (b)(2), respectively. EPA has
simplified the language by removing these redundant requirements and
removed possible confusion caused by two sets of requirements.
    In addition to removing these redundant requirements, EPA is
proposing to add provisions that provide specific information on what
is required in the Notification of Compliance Status for POTW, see
63.1591(b). We have proposed that submitting an Inspection and
Monitoring Plan required for POTW meeting the HAP fraction emitted
standard satisfies the requirement for submitting a Notification of
Compliance Status. We have also clarified in the proposed rule, for new
or reconstructed POTW that select the cover and control compliance
option, the Notification of Compliance Status report must include a
description of the POTW treatment units and installed covers, in
addition to the performance test results.
    Inspection and Monitoring Plan. The Inspection and Monitoring Plan
is required in 40 CFR 63.1588(c) for a POTW meeting the HAP fraction
emitted standard. It requires the POTW to document their plan for
determining the HAP faction emitted, including the test methods and
equipment to be used to collect the necessary data, the method for
calculating the HAP fraction emitted, and the method that will be used
to demonstrate continuous compliance with the HAP fraction emitted
standard. The Inspection and Monitoring Plan must be submitted for
approval. EPA is proposing in this rulemaking that the Inspection and
Monitoring Plan can only be approved by the EPA and the authority to
approve this plan cannot be delegated to a state, local or tribal
agency. Because the methods and procedures used to determine the HAP
fraction emitted are critical in accurately determining whether the
POTW is in compliance, and the continuous compliance monitoring methods
proposed by the POTW in their Inspection and Monitoring Plan could vary
widely, EPA is retaining this authority to ensure that consistent and
accurate test and monitoring methods are used. EPA considers it
necessary to keep this approval authority so that all Inspection and
Monitoring Plans can be reviewed consistently by one agency.
    Test Methods and Modeling Procedures/Software. In the Inspection
and Monitoring Plans, the POTW must specify the test methods they will
use to determine flowrates and HAP concentrations of incoming
wastewater streams, as well as how they will model and determine their
HAP emissions. We are considering requiring specific test methods that
must be used to determine the flowrate of wastewater to the POTW and
the HAP concentrations in incoming wastewater streams. We are also
considering requiring specific modeling procedures and/or software to
be used to determine HAP emissions. By specifying the specific test
methods and modeling procedures to be used for this data and not
allowing POTW to select any method they choose, EPA can ensure
consistency and accuracy of the data used to determine compliance with
the rule. EPA requests comment on whether we should require specific
test methods and modeling procedures/software in the final regulation.
We request comment on which test methods or modeling procedures/
software should be required. We are interested in information on test
methods and modeling procedures/software with respect to their
accuracy, what are typically used at POTW, and whether there are
specific methods that are required in Title V or NPDES permit
requirements.
6. Other Corrections or Clarifications
    The EPA is also proposing the following technical corrections:
     Revising all references to ``new or reconstructed POTW''
to refer to ``new POTW'' because the definition of ``new'' includes
reconstructed POTW.
     Combining text from 40 CFR 63.1581 and 63.1582 because the
language was redundant and confusing. Revising 40 CFR 63.1581 to
include all combined text. Revising 40 CFR 63.1583(c) to include the
text from the current 40 CFR 63.1582(c).
     Revising 40 CFR 63.1586(b)(1) to require covers ``designed
and operated to prevent exposure of the wastewater to the atmosphere.''
instead of ``designed and operated to minimize exposure of the
wastewater to the atmosphere.'' This clarification has also been made
to the definition of ``cover'' in 40 CFR 63.1595.
     Revising 40 CFR 63.1587 to include compliance requirements
that are currently found in 40 CFR 63.1584 and 63.1587 and deleting 40
CFR 63.1584.
     Revising all references to ``annual'' rolling average to
``12-month'' rolling

average to clarify that the HAP fraction must be determined on a
monthly basis and not an annual basis.
     Revising all references to ``annual HAP mass loadings''
and ``annual HAP emissions'' to now state ``monthly HAP mass loadings''
and ``monthly HAP emissions'' to further clarify that the HAP faction
must be determined on a monthly basis.
     Clarifying method for calculating the HAP fraction
emitted. Moving the detailed instructions about how the HAP fraction
emitted should be calculated from 40 CFR 63.1588(c)(4) to 40 CFR
63.1588(c)(3). The requirements in 40 CFR 63.1588(c)(3) specifically
address how the HAP fraction emitted should be calculated, while the
requirements in 40 CFR 63.1588(c)(4) are about monitoring for
continuous compliance.
     Revising 40 CFR 63.1588(a)(3) to clarify that a cover
defect must be repaired within 45 ``calendar'' days; currently the
paragraph says ``45 days.''
     Adding definitions of existing source/POTW and new source/
POTW to 40 CFR 63.1595 to clarify the date that determines whether a
POTW is existing or new.
     Revising the definition of ``affected source'' in 40 CFR
63.1595 to clarify that the affected source is the source that is
subject to the rule.
     Revising references to ``POTW treatment plant'' to refer
to ``POTW'' to clarify that the rule applies to all parts of the POTW
and not just the treatment plant portion. Updating the title of 40 CFR
63.1588 to ``How do Group 1 and Group 2 POTW demonstrate compliance?''
from ``What inspections must I conduct?'' The new title better reflects
the contents of this section.
     Removing the details on how to calculate the HAP fraction
emitted from the definition of HAP fraction emitted. The procedure for
how to calculate the HAP fraction emitted is provided within the text
of the rule. Having a summarized version of this procedure in the
definition was redundant and could cause confusion where the language
was not the same.
     Revising two references to dates to insert the actual
date. The phrase ``six months after October 26, 1999'' was replaced
with ``April 26, 2000''; and the phrase ``60 days after October 26,
1999'' was replaced with ``December 27, 1999''. These changes do not
result in a change in the date, it only clarifies the specific dates
being referenced.
     Clarifying that the reports required in 40 CFR
63.1589(b)(1) include the records associated with the HAP loading and
not just the records associated with the HAP emissions determination.
     Removing definition of ``Reconstruction'' in 40 CFR
63.1595 as ``Reconstruction'' is already defined in the General
Provisions of 40 CFR 63.2.

E. What compliance dates are we proposing?

    The EPA is proposing that all of the amendments being proposed in
this action would be effective on the date 30 days after these proposed
amendments are final, see 40 CFR 63.1587. Additionally, the EPA is
proposing a 12-month compliance schedule so that existing non-
industrial (Group 2) POTW treatment plants have time to develop the
recordkeeping and reporting systems needed to comply with the
requirements of the HAP fraction emission limit. Likewise, industrial
(Group 1) POTW treatment plants need time to develop methods to
demonstrate compliance with both the POTW NESHAP and the other
applicable NESHAP, including development of the recordkeeping and
reporting systems, and 12 months will provide industrial (Group 1) POTW
the time needed to make these changes. Finally, POTW need time to
examine their SIU pretreatment permits and evaluate if additional
limits should be incorporated, and issue those revised permits. We
estimate that 12 months should provide the time necessary to perform
this evaluation and revise permits, as needed. Table 4 below describes
the compliance dates and applicable standards for new and existing
sources based on their subcategory and date of construction or
reconstruction.