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[[pp. 52877-52926]] NESHAPS: Final Standards for Hazardous Air Pollutants for
Note: EPA no longer updates this information, but it may be useful as a reference or resource.
[Federal Register: September 30, 1999 (Volume 64, Number 189)]
[Rules and Regulations]
[Page 52877-52926]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr30se99-25]
[[pp. 52877-52926]] NESHAPS: Final Standards for Hazardous Air Pollutants for
Hazardous Waste Combustors
[[Continued from page 52876]]
[[Page 52877]]
97% since 1990, from 431 g TEQ/yr to 13.1 g TEQ/yr.123
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\123\ USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume V: Emission Estimates and Engineering Costs'',
July 1999. See also 63 FR 17338, April 10, 1998.
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c. What Is the MACT Floor for New Sources? At proposal, we
identified floor control for new sources as temperature control at the
inlet to the particulate matter control device at 409 deg.F. The
proposed floor emission level was 0.20 ng TEQ/dscm, or temperature at
the inlet to the particulate matter control device not to exceed
409 deg.F. In the May 1997 NODA, we identified an alternative data
analysis method to identify floor control and the floor emission level.
The May 1997 NODA dioxin/furan floor control for new sources was
defined as temperature control at the inlet to the electrostatic
precipitator or fabric filter at 400 deg.F, which was based on an
engineering evaluation of the emissions data and other available
information. That analysis resulted in a floor emission level of 0.20
ng TEQ/dscm, or 0.40 ng TEQ/dscm and temperature at the inlet to the
electrostatic precipitator or fabric filter not to exceed 400 deg.F. We
continue to believe that the floor methodology is appropriate for new
sources and we adopt this approach in this final rule.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
both the April 1996 proposal and May 1997 NODA, we proposed activated
carbon injection as beyond-the-floor control and a beyond-the-floor
standard of 0.20 ng TEQ/dscm for new sources. For reasons discussed
above for existing sources, we conclude that it is also not cost-
effective for new cement kilns to achieve this level. Thus, we do not
adopt a beyond-the-floor dioxin/furan standard for new cement kilns.
3. What Are the Mercury Standards?
In today's rule, we establish a standard for existing and new
cement kilns that limits mercury emissions to 120 and 56 g/
dscm, respectively. The rationale for these standards is discussed
below.
a. What Is the MACT Floor for Existing Sources? All cement kilns
use either electrostatic precipitators or fabric filters for
particulate matter control. However, since mercury is generally in the
vapor form in and downstream of the combustion chamber, including the
air pollution control device, electrostatic precipitators and fabric
filters do not achieve good mercury control. Mercury emissions from
cement kilns are currently regulated by the Boiler and Industrial
Furnace rule, which establishes limits on the maximum feedrate of
mercury in total feedstreams (e.g., hazardous waste, raw materials,
coal). Thus, MACT floor control is based on hazardous waste feed
control.
In the April 1996 proposal, we identified floor control as
hazardous waste feedrate control not to exceed a feedrate level of 110
g/dscm, expressed as a maximum theoretical emission
concentration, and proposed a floor standard of 130 g/dscm
based on an analysis of data from all cement kilns with a hazardous
waste mercury feedrate of this level or lower. (61 FR at 17393.) In May
1997 NODA, we conducted a breakpoint analysis on low to high ranked
mercury emissions data from sources floor control and established the
floor level as the test condition average emission of the breakpoint
source. The breakpoint analysis was intended to reflect an engineering-
based evaluation of the data so that the few cement kilns spiking
mercury during compliance testing did not drive the floor standard to
levels higher than the preponderance of the emissions data. We reasoned
that sources with emissions higher than the breakpoint source were not
controlling the hazardous waste feedrate of mercury to levels
representative of MACT. This analysis resulted in a MACT floor level of
72 g/dscm. (62 FR at 24227.)
For today's rule, in response to comments questioning our May 1997
NODA approach, we use a revised engineering evaluation and data
analysis method to establish the MACT floor for mercury. As discussed
in greater detail in the methodology section previously, we use an
aggregate feedrate approach to establish MACT floors for the three
metal hazardous air pollutant groups and hydrochloric acid/chlorine
gas. The aggregate feedrate approach first identifies a MACT floor
feedrate level for mercury and then establishes the floor emission
level as the highest emissions level achieved by any cement kilns using
floor control or better. Using this approach, the resulting mercury
floor emission level is 120 g/dscm.
We received comments on several overarching issues including the
appropriateness of considering feedrate control of mercury in hazardous
waste as a MACT floor control technique and the specific procedure of
identifying breakpoints in arrayed emissions data. These issues and our
response to them are discussed in the floor methodology section in Part
Four, Section V. In addition, we received comment on a special
provision that would allow cement kilns (and lightweight aggregate
kilns) to petition the Administrator for an alternative mercury
standard for kilns with mercury concentrations in their mineral and
related process raw materials that causes an exceedance of the emission
standard. This issue and the alternative standard promulgated in the
final rule is fully discussed in Part Five, Section X.A.
We also received comments from the cement manufacturing industry
indicating that cement kilns with in-line raw mills have unique design
and operating procedures that necessitate the use of emission averaging
when demonstrating compliance with the emission standards. These
commenters stated that the mercury standard is not achievable without a
procedure for kilns to emissions average. The commenters supported a
provision allowing cement kilns with in-line raw mills to demonstrate
compliance with the emission standards on a time-weighted average basis
to account for different emission characteristics when the raw mill is
active as opposed to when it is inactive. After fully considering
comments received, we adopt an emission averaging provision in the
final rule. This provision is fully discussed in Part Five, Section
X.E.
Several commenters expressed concern that the mercury emissions
data base for cement kilns is comprised of normal data, that is, cement
kilns did not spike mercury during RCRA compliance testing as they did
for other metals and chlorine. Thus, commenters stated that an
emissions variability factor should be added to a floor level derived
directly from the emissions data to ensure that the floor emission
level is being achieved in practice. As discussed in Section V.D.1
above, we conclude that emissions variability is adequately accounted
for by the MACT floor methodology finalized today.
We estimate that 85 percent of cement kilns currently meet the
floor level. The national annualized compliance cost for cement kilns
to reduce mercury emissions to comply with the floor level is $1.1
million for the entire hazardous waste burning cement industry and will
reduce mercury emissions by 0.2 Mg/yr or 15 percent from current
baseline emissions.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the April 1996 NPRM, we proposed a beyond-the-floor
standard of 50 g/dscm based on flue gas temperature reduction
to 400 deg.F followed by activated carbon injection for mercury
capture. (61 FR at 17394.) In the May 1997 NODA, we considered a
beyond-the-floor standard of 30 g/dscm based on activated
carbon
[[Page 52878]]
injection; however, an evaluation was not conducted to determine if
such a level would be cost-effective. (62 FR at 24227.)
In developing the final rule, we identified three techniques for
control of mercury as a basis to evaluate a beyond-the-floor standard:
(1) Activated carbon injection; (2) limiting the feed of mercury in the
hazardous waste; and (3) limiting the feed of mercury in the raw
materials. The results of each analysis are discussed below.
i. Activated Carbon Injection. To investigate activated carbon
injection, we applied a carbon injection capture efficiency of 80
percent to the floor emission level of 120 g/dscm. Our basis
for selecting a capture efficiency of 80 percent 124 is
discussed in the support document.125 The resulting beyond-
the-floor emission level is 25 g/dscm.
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\124\ We received many comments on the use of activated carbon
injection as a beyond-the-floor control technique at cement kilns.
Since we do not adopt a beyond-the-floor standard based on activated
carbon injection in the final rule, these comments and our responses
to them are only discussed in our document that responds to public
comments.
\125\ USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies.'' July 1999.
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We then determined the cost of achieving this reduction to
determine if a beyond-the-floor standard of 25 g/dscm would be
appropriate. The national incremental annualized compliance cost for
the remaining cement kilns to meet this beyond-the-floor level, rather
than comply with the floor controls, would be approximately $11.1
million for the entire hazardous waste burning cement kiln industry and
would provide an incremental reduction in mercury emissions nationally
beyond the MACT floor controls of 0.7 Mg/yr. Based on these costs of
approximately $16 million per additional Mg of mercury removed, we
conclude that this mercury beyond-the-floor option for cement kilns is
not acceptably cost-effective nor otherwise justified. Therefore, we do
not adopt this beyond-the-floor standard.
ii. Limiting the Feedrate of Mercury in the Hazardous Waste. We
also considered a beyond-the-floor standard of 50 g/dscm based
on limiting the feedrate of mercury in the hazardous waste. An emission
level of 50 g/dscm represents the practicable extent that
additional feedrate control of mercury in hazardous waste (beyond
feedrate control needed to achieve the floor emission level) can be
used and still achieve modest emissions reductions. We investigated the
cost of achieving this reduction to determine if this beyond-the-floor
standard would be appropriate. The national incremental annualized
compliance cost for cement kilns to meet a beyond-the-floor level of 50
g/dscm, rather than comply with the floor controls, would be
approximately $4.2 million for the entire hazardous waste burning
cement kiln industry and would provide an incremental reduction in
mercury emissions nationally beyond the MACT floor controls of 0.4 Mg/
yr. Based on these costs of approximately $10.9 million per additional
Mg of mercury removed, we conclude that this mercury beyond-the-floor
option for cement kilns is not warranted. Therefore, we did not adopt
this mercury beyond-the-floor standard.
iii. Limiting the Feedrate of Mercury in Raw Materials. Finally, we
considered a beyond-the-floor standard based on limiting the feedrate
of mercury in the raw materials. Cement manufacturing involves the
heating of raw materials such as limestone, clay, shale, sand, and iron
ore. Limestone, shale, and clay comprise the vast majority of raw
material feed to the kiln, and these materials are typically mined at
quarries nearby the cement kiln. Since feed materials can contain
significant quantities of hazardous air pollutants, we considered
establishing a beyond-the-floor standard based on limiting the feedrate
of mercury in these raw materials. A source can achieve a reduction in
mercury emissions by substituting a feed material containing lower
levels of mercury for a primary raw material with higher mercury
levels. For example, shale is the primary feed material used as a
source of silica. Under this beyond-the-floor option, a source using a
high mercury-containing shale could substitute a feed material lower in
mercury such as a coal ash to achieve lower mercury emissions. This
beyond-the-floor option appears to be less cost-effective compared to
either of the options evaluated above, however. This conclusion is
based on the fact that cement kilns are sited proximate to primary raw
material supply and transporting large quantities of an alternative
source of raw material(s) is likely to be cost-prohibitive, thereby
making a beyond-the-floor standard not cost-effective. Therefore, we do
not adopt this mercury beyond-the-floor standard.
Thus, the promulgated mercury standard for existing hazardous waste
burning cement kilns is the floor level of 120 g/dscm.
c. What Is the MACT Floor for New Sources? In the April 1996
proposal, we identified floor control for new sources as hazardous
waste mercury feedrate control not to exceed a feedrate level of 28
g/dscm expressed as a maximum theoretical emission
concentration. We proposed a floor level of 82 g/dscm. We
discussed a floor emission level for new cement kilns in the May 1997
NODA of 72 g/dscm, based on a floor feedrate control level of
110 g/dscm.
Today we identify floor control for new cement kilns as feedrate
control of mercury in the hazardous waste, expressed as a maximum
theoretical emission concentration, based on the single source with the
best aggregate feedrate of mercury in hazardous waste. Using the
aggregate feedrate approach to establish this floor level of control
and the corresponding floor emission level, we identify a MACT floor
emission level of 56 g/dscm for new hazardous waste burning
cement kilns.126
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\126\ Given that the emission level is substantially higher than
the feedrate level expressed as a maximum theoretical emission
concentration, 56 vs 7 g/dscm, the contributions of mercury
from raw materials and coal for the floor-setting source must be
substantial.
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d. What Are Our Beyond-the-Floor Considerations for New Sources? At
proposal, we based beyond-the-floor control for new cement kilns on
activated carbon injection and proposed a standard of 50 g/
dscm. In the May 1997 NODA we considered a beyond-the-floor standard of
30 g/dscm based on activated carbon injection as done for
existing sources.
We identified two techniques for control of mercury as a basis to
evaluate a beyond-the-floor standard for new sources: (1) Activated
carbon injection; and (2) limiting the feedrate of mercury in the
hazardous waste. The results of each analysis are discussed below.
i. Activated Carbon Injection. As discussed above, we conclude that
flue gas temperature reduction to 400 deg.F followed by activated
carbon injection to remove mercury is an appropriate beyond-the-floor
control option for improved mercury control at cement kilns. Based on
the MACT floor emission level of 56 g/dscm and assuming a
carbon injection capture efficiency of 80 percent, we identified a
beyond-the-floor emission level of 10 g/dscm. We then
determined the cost of achieving this reduction to determine if a
beyond-the-floor standard of 10 g/dscm would be appropriate.
The incremental annualized compliance cost for one new large cement
kiln to meet this beyond-the-floor level, rather than comply with floor
controls, would be approximately $2.3 million and would provide an
incremental reduction in mercury emissions beyond the MACT floor
controls of approximately 0.17 Mg/yr. For a new small cement kiln, the
[[Page 52879]]
incremental annualized compliance cost would be approximately $0.9
million and would provide an incremental reduction in mercury emissions
beyond the MACT floor controls of approximately 0.04 Mg/yr. Based on
these costs of approximately $13-22 million per additional Mg of
mercury removed, we concluded that a beyond-the-floor standard of 10
g/dscm is not justified due to the high cost of compliance and
relatively small mercury emissions reductions.
ii. Limiting the Feedrate of Mercury in Hazardous Waste. We also
considered a beyond-the-floor standard based on limiting the feedrate
of mercury in the hazardous waste. Considering that the floor emission
level for new cement kilns is approximately half of the floor emission
level for existing kilns (56 versus 120 g/dscm), we conclude
that a mercury beyond-the-floor standard for cement kilns is not
warranted. This conclusion is based on the limited incremental
emissions reductions achieved 127 and because the cost-
effectiveness of beyond-the-floor controls for new cement kilns would
be even higher than for existing sources, which we found unacceptable
in paragraph (b) above. Therefore, we do not adopt a mercury beyond-
the-floor standard based on limiting feedrate of mercury in hazardous
waste.
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\127\ Achieving substantial additional mercury emissions
reductions by further controls on hazardous waste feedrate may be
problematic because the mercury contribution from raw materials and
coal represents an even larger proportion of the total mercury fed
to the kiln.
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Thus, the promulgated mercury standard for new hazardous waste
burning cement kilns is the floor emissions level of 56 g/
dscm.
4. What Are the Particulate Matter Standards?
We establish standards for both existing and new cement kilns which
limit particulate matter emissions to 0.15 kg/Mg dry
feed.128 In addition, opacity cannot exceed 20 percent. We
chose the particulate matter standard as a surrogate control for the
metals antimony, cobalt, manganese, nickel, and selenium. We refer to
these five metals as ``nonenumerated metals'' because standards
specific to each metal have not been established. The rationale for
adopting these standards is discussed below.
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\128\ Approximately equivalent to a particulate matter
concentration of 0.03 gr/dscf (69 mg/dscm) as expressed in the April
1996 NPRM and May 1997 NODA. The calculation is approximate due to
the different types of cement kilns and their associated flow rates.
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a. What Is the MACT Floor for Existing Sources? In the April 1996
proposal, we discussed particulate matter floor control based upon the
performance of a fabric filter with an air-to-cloth ratio of 2.3 acfm/
f, 2 resulting in a nominal floor emission level of 0.065
gr/dscf. However, we believed it more appropriate to establish the
floor standard based on the cement kiln 1971 New Source Performance
Standard. (See discussion in 61 FR at 17392.) The 1971 New Source
Performance Standard is 0.15 kg/Mg dry feed (0.30 lb/ton of dry feed).
(see 40 CFR 60.60.) Cement kilns currently achieve this standard with
well-designed and properly operated electrostatic precipitators and
fabric filters.
In the May 1997 NODA, we considered two data analysis methods to
identify the particulate matter floor emission level. The first method
established and expressed the floor level equivalent to the existing
New Source Performance Standard promulgated in 1971. We subsequently
proposed and finalized this approach for nonhazardous waste burning
cement kilns. See 63 FR at 14198-199 and 64 FR 31898, respectively. The
second approach discussed expressed the New Source Performance Standard
as a stack gas concentration limit, as opposed to a production-based
emission limit format. The May 1997 reevaluation suggested that the
1971 New Source Performance Standard was approximately equivalent to a
particulate matter concentration of 0.03 gr/dscf (69 mg/
dscm).129 We indicated a preference for expressing the
particulate matter standard on a concentration basis because we also
proposed that sources would comply with the particulate matter standard
with a particulate matter continuous emissions monitoring system.
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\129\ See USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999 for a discussion of the approximate
equivalency.
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However, we now conclude that basing the floor on the 1971 New
Source Performance Standard is the most appropriate approach. Cement
kilns achieve the 1971 New Source Performance Standard with well-
designed and properly operated fabric filters and electrostatic
precipitators. Since approximately 20% of hazardous waste burning
cement kilns now are subject to the 1971 New Source Performance
Standard, consideration of this existing federal regulation as a floor
is appropriate because greater than 12% of existing sources are
achieving it. The available emissions test data show a wide range of
particulate matter results--some emissions data are well below while
other data are at the 1971 New Source Performance Standard
level.130 Even though the hazardous waste burning cement
kiln particulate matter data span two orders of
magnitude,131 we have limited data on design parameters of
the particulate matter control device and could not identify a cause
(i.e., differentiate among control equipment) for the wide range in
particulate matter emissions. We thus believe that the variation
reflects normal operating variability. Therefore, the MACT floor
emission level for existing cement kilns is the 1971 New Source
Performance Standard.
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\130\ The variation in the particulate matter data is consistent
with data from nonhazardous waste burning cement kilns. We neither
expect nor have any data indicating that waste-burning operations
increase particulate matter emissions at a cement kiln. An estimated
30% of existing nonhazardous waste burning cement kilns are subject
to the requirements of the new Source Performance Standard for
cement plants. The particulate matter data for these kilns also
exhibit a wide range in measurements. (63 FR at 14198.)
\131\ USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999.
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The New Source Performance Standard at Sec. 60.62 also specifies
that opacity must be monitored continuously and establishes an opacity
standard of 20 percent as a measure to ensure compliance with the
particulate matter standard. We are therefore also adopting this
opacity standard for today's rule.132 We are adopting it for
the final rule because: (1) We proposed to base the particulate matter
standard for hazardous waste burning cement kilns on the New Source
Performance Standard, and the opacity standard is an integral component
of that standard; and (2) we proposed to base the MACT particulate
matter standard for nonhazardous waste burning cement kilns on the New
Source Performance Standard and explicitly identified both the
particulate emission and opacity components of the standard. Hazardous
waste burning cement kiln stakeholders have commented on both the
nonhazardous waste and hazardous waste cement kiln proposed rules and
suggest that there is little or no difference in emissions from the two
classes of kilns and that they should be regulated the same. Although
we do not agree that emissions of all hazardous pollutants are the same
for both classes of kilns and should be regulated the same, we agree
that particulate
[[Page 52880]]
emissions are comprised largely of entrained raw material and are not
significantly affected by burning hazardous waste. Thus, we concur that
the standard for particulate matter should be the same for both classes
of sources and are therefore adopting the New Source Performance
Standard opacity standard for the final rule.133 In the NPRM
and the May 1997 NODA, we proposed to express the particulate matter
standard on a concentration basis rather than express it as the same
format as the 1971 New Source Performance Standard, which is a
production-based emission limit format. However, because we are not yet
requiring sources to document compliance with the particulate matter
standard by using a particulate matter continuous emissions monitoring
system in this final rule 134, we establish and express the
floor emission level equivalent to the 1971 New Source Performance
Standard. Thus, the particulate matter floor is 0.15 kg/Mg dry feed
based on the performance of a well-designed and operated fabric filter
or electrostatic precipitator.
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\132\ Given that we adopt the New Source Performance Standard
for particulate matter and opacity for the MACT standards for
hazardous waste burning cement kilns, we exempt these sources from
the New Source Performance Standard to avoid duplicative regulation.
See Sec. 63.1204(h).
\133\ We are not adopting the opacity standard component of the
New Source Performance Standard for hazardous waste burning
lightweight aggregate kilns, however. This is because that opacity
standard (see Sec. 60.732) is a measure to ensure compliance with
the particulate emissions component of that standard, which is
substantially higher than the MACT standard that we promulgate
today. Thus, the NSPS opacity standard for lightweight aggregate
kilns would not be a useful measure of compliance with today's
particulate matter standard for lightweight aggregate kilns.
\134\ We anticipate rulemaking on a particulate matter
continuous emissions monitoring system requirement for hazardous
waste combustors in the near future. Under this rulemaking,
combustors would be required to document compliance with national
emission standards by complying with continuous emissions monitoring
system-based particulate matter levels that are being achieved by
sources equipped with MACT controls. See Part Five, Section VII.C.
for details.
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Several commenters expressed concern in their comments to the NPRM
that the Agency identified separate, different MACT pools and
associated MACT controls for particulate matter, semivolatile metals,
and low volatile metals, even though all three are controlled, at least
in part, by a particulate matter control device. Commenters stated that
our approach is likely to result in three different design
specifications. We agree with the need to use the same pool for
particulate matter, semivolatile metals, and low volatile metals and
used the same initial MACT pool to establish the floor levels for these
pollutants. See Part Four, Section V for a detailed discussion of our
floor methodology.
We estimate that over 60 percent of cement kilns currently meet the
floor emission level. The national annualized compliance cost for
cement kilns to reduce particulate matter emissions to comply with the
floor level is $6.2 million for the entire hazardous waste burning
cement industry and will reduce nonenumerated metals and particulate
matter emissions by 1.1 Mg/yr and 873 Mg/yr, respectively, or over 30
percent from current baseline emissions.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the proposal and May 1997 NODA, we considered a beyond-the-
floor level of 34 mg/dscm (0.015 gr/dscf) based on improved particulate
matter control. However, after examining the costs of such control and
the relatively low incremental reductions in air emissions that would
result, we determined that a beyond-the-floor standard would not likely
be cost-effective. (61 FR at 17393.)
Several commenters support a beyond-the-floor option for
particulate matter because some cement kilns are readily achieving
particulate matter levels well below the floor emission level based on
the New Source Performance Standard. Other commenters oppose a beyond-
the-floor option for cement kilns because of the high costs and
anticipated poor cost-effectiveness. In the final rule, we evaluated a
beyond-the-floor emission level for existing cement kilns to determine
if such a level would be appropriate.
Improved particulate matter control for existing cement kilns would
require the use of high efficiency electrostatic precipitators and
fabric filters. These may include fabric filters with low air-to-cloth
ratios, high performance fabrics, electrostatic precipitators with
large specific collection areas, and advanced control systems.
Currently, the majority of hazardous waste burning cement kilns use
electrostatic precipitators for particulate matter control and usually
achieve removal efficiencies greater than 99.8%. Cement kilns can meet
the MACT floor with well designed and properly operated particulate
matter control equipment that for many kilns may require only minor
system upgrades from their current systems. A beyond-the-floor
standard, however, would likely involve more than a minor system
upgrade, and may require new control equipment or retrofitting a
baghouse with new higher performance fabric materials. The total
annualized costs associated with such major system upgrades would be
significant, while only achieving modest incremental emissions
reductions in particulate matter and nonenumerated metals.
In the final rule, we considered a beyond-the-floor level of 34 mg/
dscm, approximately one-half the New Source Performance Standard, for
existing cement kilns based on improved particulate matter control. For
analysis purposes, improved particulate matter control entails the use
of higher quality fabric filter bag material. We then determined the
cost of achieving this level of particulate matter, with corresponding
reductions in the nonenumerated metals for which particulate matter is
a surrogate, to determine if this beyond-the-floor level would be
appropriate. The national incremental annualized compliance cost for
cement kilns to meet this beyond-the-floor level, rather than comply
with the floor controls, would be approximately $7.4 million for the
entire hazardous waste burning cement kiln industry and would provide
an incremental reduction in nonenumerated metals emissions nationally
beyond the MACT floor controls of 0.7 Mg/yr. Based on these costs of
approximately $10.7 million per additional Mg of nonenumerated metals
emissions removed, we conclude that this beyond-the-floor option for
cement kilns is not acceptably cost-effective nor otherwise justified.
Therefore, we do not adopt this beyond-the-floor standard. The
promulgated particulate matter standard for existing hazardous waste
burning cement kilns is the floor emission level of 0.15 kg/Mg dry feed
and opacity not to exceed 20 percent.
c. What Is the MACT Floor for New Sources? In the proposal, we
defined floor control based on the performance of a fabric filter with
an air-to-cloth ratio of less than 1.8 acfm/ft2. As discussed for
existing sources, we proposed the floor level based on the existing
cement kiln New Source Performance Standard. 61 FR at 17400. In the May
1997 NODA, we again considered basing the floor emission level on the
New Source Performance Standard and solicited comment on the two
alternatives to express the standard identical to those discussed above
for existing cement kilns. (62 FR at 24228.)
All cement kilns use fabric filters and electrostatic precipitators
to control particulate matter. As discussed earlier, we have limited
detailed information on the design and operation characteristics of
existing control equipment currently used by cement kilns. As a result,
we are unable to identify a specific design or technology that can
consistently achieve lower emission levels than the controls used by
cement kilns achieving the New Source Performance Standard. Cement
kilns meet the New Source Performance Standard with well-
[[Page 52881]]
designed and properly operated fabric filters and electrostatic
precipitators. Thus, floor control for new cement kilns is also a well-
designed and properly operated fabric filter and electrostatic
precipitator. As discussed for existing sources, we conclude that
expressing the floor based on the New Source Performance Standards is
appropriate for the final rule. Therefore, the MACT floor level for new
cement kilns is 0.15 kg/Mg dry feed and opacity not to exceed 20
percent.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the April 1996 NPRM and May 1997 NODA, we considered a beyond-the-floor
standard based on improved particulate matter control to be consistent
with existing sources. However, we proposed that such a beyond-the-
floor level was not likely cost-effective.
As discussed for existing sources, we considered a beyond-the-floor
level of 34 mg/dscm, approximately one-half the New Source Performance
Standard, for new cement kilns based on improved particulate matter
control. For analysis purposes, improved particulate matter control
entails the use of higher quality fabric filter bag material. We then
determined the cost of achieving this level of particulate matter, with
corresponding reductions in the nonenumerated metals for which
particulate matter is a surrogate, to determine if this beyond-the-
floor level would be appropriate. The incremental annualized compliance
cost for one new large cement kiln to meet this beyond-the-floor level,
rather than comply with floor controls, would be approximately $309,000
and would provide an incremental reduction in nonenumerated metals
emissions of approximately 0.18 Mg/yr.135 For a new small
cement kiln, the incremental annualized compliance cost would be
approximately $120,000 and would provide an incremental reduction in
nonenumerated metals emissions of approximately 0.04 Mg/yr. Based on
these costs of approximately $1.7-3.0 million per additional Mg of
nonenumerated metals removed, we conclude that a beyond-the-floor
standard of 0.015 gr/dscf is not justified due to the high cost of
compliance and relatively small nonenumerated metals emission
reductions. Thus, the particulate matter standard for new cement kilns
is the floor level of 0.15 kg/Mg dry feed and opacity not to exceed 20
percent.
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\135\ Based on the data available, the average emissions in sum
of the five nonenumerated metals from cement kilns using MACT
particulate matter control is approximately 80 g/dscm. To
estimate emission reductions of the nonenumerated metals, we assume
a linear relationship between a reduction in particulate matter and
these metals.
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5. What Are the Semivolatile Metals Standards?
Today's rule establishes standards for existing and new cement
kilns that limit semivolatile metals emissions to 240 and 180
g/dscm, respectively. The rationale for these standards is
discussed below.
a. What Is the MACT Floor for Existing Sources? In the April 1996
proposal, we defined floor control as a fabric filter with an air-to-
cloth ratio less than 2.1 acfm/ft 2 and a hazardous waste
feedrate level of 84,000 g/dscm, expressed as a maximum
theoretical emission concentration. The proposed floor emission level
was 57 g/dscm, based on the level a source with properly
designed and operated floor technology could achieve. In the proposed
rule, we also solicited comment on an alternative floor approach
whereby ``equivalent technology'' to MACT control is identified and
evaluated. This approach resulted in an emission level of 160
g/dscm (See 61 FR at 17395.) In the May 1997 NODA, we
discussed a floor methodology where we used a breakpoint analysis to
identify sources that were not using floor control with respect either
to semivolatile metals hazardous waste feedrate or emissions control.
Under this approach, we ranked semivolatile metals emissions data from
sources that were using MACT floor particulate matter control, i.e.,
sources achieving the New Source Performance Standard or better. We
identified the floor level as the test condition average associated
with the breakpoint source. Thus, sources with atypically high
emissions because of high semivolatile metals feedrates or poor
semivolatile metals control even though they appeared to be using floor
control for particulate matter were screened from the pool of sources
used to define the floor emission level. Based on this analysis, we
identified a floor level in the May 1997 NODA of 670 g/dscm.
(See 62 FR at 24228.)
As discussed previously in the methodology section, we use a
revised engineering evaluation and data analysis method to establish
the MACT floor for semivolatile metals based on the same underlying
data previously noticed for comment. The aggregate feedrate approach,
in conjunction with floor control for particulate matter, identified a
semivolatile metals floor emission level of 650 g/dscm.
In addition, several commenters stated strongly that the feedrate
of semivolatile metals in hazardous waste cannot be considered MACT
floor control in conjunction with particulate matter control. These
commenters believe that floor control for semivolatile metals is
control of particulate matter only. We disagree with these commenters
for reasons we discuss in Part Four, Section V of the preamble, mainly
that feedrate is currently control for hazardous waste combustors under
RCRA regulations, and conclude that control of the feedrate of
semivolatile metals in hazardous waste is floor control, in conjunction
with particulate matter control.
We estimate that approximately 60 percent of cement kilns currently
meet this floor level. The national annualized compliance cost for
cement kilns to reduce semivolatile metal emissions to comply with the
floor level is $1.3 million for the entire hazardous waste burning
cement industry and will reduce semivolatile metal emissions by 19.5
Mg/yr or 65 percent from current baseline emissions.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the proposal, we considered a beyond-the-floor standard for
semivolatile metals based on improved particulate matter control below
the New Source Performance Standard. However, we concluded that a
beyond-the-floor standard would not be cost-effective, given that the
semivolatile metal floor level of 57 g/dscm alone resulted in
an estimated 94 percent semivolatile metal reduction in emissions. (see
61 FR at 17396.) In the May 1997 NODA, we considered a lower
particulate matter emissions level of 0.015 gr/dscf, based on improved
particulate matter control, as a beyond-the-floor standard to further
reduce semivolatile and low volatile metals. Even though we did not
quantify cost-effectiveness values, we expressed concern that a beyond-
the-floor standard would not likely be cost-effective. (see 62 FR at
24229.)
Commenters believed there were several control techniques that
should be considered, therefore, we identified three potential beyond-
the-floor control techniques in developing the final rule: (1) Limiting
the feedrate of semivolatile metals in hazardous waste; (2) improved
particulate matter control; and (3) limiting the feedrate of
semivolatile metals in raw materials. We conclude that a beyond-the-
floor standard is warranted based on limiting the feedrate of
semivolatile metals in hazardous waste. The results of each analysis
are discussed below.
i. Limiting the Feedrate of Semivolatile Metals in Hazardous Waste.
Under this approach, we selected a beyond-the-floor emission level of
240
[[Page 52882]]
g/dscm from among the range of possible levels that reflect
improved feedrate control. This emission level represents a significant
increment of emission reduction from the floor of 650 g/dscm,
it is within the range of levels that are likely to be reasonably
achievable using feedrate control, and it is consistent with the
incinerator standard thereby advancing a potential policy objective of
essentially common standards among combustors of hazardous waste.
The national incremental annualized compliance cost for the
remaining cement kilns to meet this beyond-the-floor level, rather than
comply with the floor controls, would be approximately $2.7 million for
the entire hazardous waste burning cement kiln industry and would
provide an incremental reduction, beyond emissions at the MACT floor,
in semivolatile metal emissions nationally of 5.5 Mg/yr. The cost-
effectiveness of this standard would be approximately $500,000 per
additional Mg of semivolatile metals removed. Notwithstanding the
relatively poor cost-effectiveness of this standard on a dollar per Mg
removed basis, we conclude that additional beyond-the-floor control of
the feedrate of semivolatile metals in hazardous waste to achieve an
emission level of 240 g/dscm is warranted because this
standard would reduce lead and cadmium emissions which are particularly
toxic hazardous air pollutants. See Health Human Effects discussion in
USEPA, ``Technical Background Document for HWC MACT Standards: Health
and Ecological Risk Assessment'', July 1999. Further, approximately 90%
of the lead and cadmium fed to the cement kiln is from the hazardous
waste,136 not the raw material (about 9%) or coal (about
1%). We are willing to accept a more marginal cost-effectiveness to
ensure that hazardous waste combustion sources are using the best
controls for pollutants introduced almost exclusively for the burning
of hazardous waste. We do so to provide a strong incentive for waste
minimization of lead and cadmium sent for combustion. By providing
stringent limits, we can help assure that hazardous waste with lead
does not otherwise move from better controlled units in other
subcategories to units in this subcategory because of a lesser degree
of control. Moreover, this beyond-the-floor semivolatile metal standard
supports our Children's Health Initiative in that lead emissions, which
are of highest significance to children's health, will be reduced by
another 20-25 percent from today's baseline. As part of this
initiative, we are committed to reducing lead emissions wherever and
whenever possible. Finally, this beyond-the-floor standard is
consistent with European Union standards for hazardous waste
incinerators of approximately 200 g/dscm for lead and cadmium
combined. For all these reasons, we accept the cost-effectiveness of
this level of feedrate control and adopt a beyond-the-floor standard of
240 g/dscm for existing cement kilns.
---------------------------------------------------------------------------
\136\ USEPA, ``Final Technical Support document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies'', July 1999.
---------------------------------------------------------------------------
Additionally, we received comments shortly before promulgation from
the cement kiln industry that expressed their achievability and
economic concerns with a beyond-the-floor standard in the range of 240
g/dscm based on limiting the feedrate of semivolatile metals
in the hazardous waste. We considered their comments in adopting the
240 g/dscm beyond-the-floor standard and included a copy of
their November 18, 1998 presentation to the Office of Management and
Budget in the docket along with our responses to their concerns, many
of which are addressed above.
ii. Improved Particulate Matter Control. We also evaluated improved
particulate matter control as a beyond-the-floor control option for
improved semivolatile metals control. Cadmium and lead are volatile at
the high temperatures within the cement kiln itself, but typically
condense onto the fine particulate at control device temperatures,
where they are collected. As a result, control of semivolatile metals
emissions is closely associated with particulate matter control.
Examples of improved particulate matter control include the use of more
expensive fabric filter bags, optimizing the design and operation
features of the existing control equipment, and the addition to or the
replacement of control equipment with a new fabric filter.
We evaluated the costs to achieve a beyond-the-floor emission level
of 240 g/dscm based on improved particulate matter control.
The national incremental annualized compliance cost for cement kilns to
meet this beyond-the-floor level, rather the floor level, would be
approximately $4.1 million for the entire hazardous waste burning
cement kiln industry and would provide an incremental reduction in
semivolatile metal emissions beyond the MACT floor controls of 5.5 Mg/
yr. Because this beyond-the-floor control option would have a cost-
effectiveness of approximately $800,00 per additional Mg of
semivolatile metal removed, contrasted to a cost-effectiveness of
approximately $500,000 using hazardous waste feedrate control and
remove an identical amount of semivolatile metals, we conclude that
basing the beyond-the-floor standard on improved particulate matter
control is not warranted.
iii. Limiting the Feedrate of Semivolatile Metals in Raw Materials.
A source can achieve a reduction in semivolatile metal emissions by
substituting a feed material containing lower levels of lead and/or
cadmium for a primary raw material with higher levels of these metals.
We expect this beyond-the-floor option to be less cost-effective
compared to either of the options evaluated above. Cement kilns are
sited proximate to primary raw material supply and transporting large
quantities of an alternative source of raw material(s) is likely to be
cost-prohibitive. Therefore, we are not adopting a semivolatile metal
beyond-the-floor standard based on limiting the feedrate of
semivolatile metals in raw materials.137
---------------------------------------------------------------------------
\137\ We, however, reject the proposition in comments that we
are without legal authority to regulate HAPs in raw materials
processed in cement kilns based on legislative history to the 1990
amendments. This legislative history is not reflected in the
statutory text, which unambiguously gives us that authority.
---------------------------------------------------------------------------
Thus, the promulgated semivolatile metals standard for existing
hazardous waste burning cement kilns is a beyond-the-floor standard of
240 g/dscm based on limiting the feedrate of semivolatile
metals in the hazardous waste.
c. What Is the MACT Floor for New Sources? In the proposal, we
defined floor control as a fabric filter with an air-to-cloth ratio
less than 2.1 acfm/ft 2 and a hazardous waste feedrate level
of 36,000 g/dscm, expressed as a maximum theoretical emission
concentration. The proposed floor emission level for new cement kilns
was 55 g/dscm. (See 61 FR at 17400.) In the May 1997 NODA, we
concluded that the floor control and emission level for existing
sources for semivolatile metals also would be appropriate for new
sources. Floor control was based on a combination of good particulate
matter control and limiting hazardous waste feedrate of semivolatile
metals. We used a breakpoint analysis of the semivolatile metal
emissions data to exclude sources achieving substantially poorer
semivolatile metal control than the majority of sources because of
atypically high semivolatile metals feedrates or poor emission control.
We established the floor level at the test condition average of the
breakpoint source: 670 g/dscm. (See 62 FR at 24229.)
As discussed above for existing sources, we developed the final
rule
[[Page 52883]]
using the aggregate feedrate approach to identify MACT floors for the
metals. See Methodology Section for detailed discussion of aggregate
feedrate approach. Using this approach, we establish the semivolatile
metal floor emission level for new sources at 180 g/dscm.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the April 1996 NPRM and May 1997 NODA, we considered a semivolatile
metal beyond-the-floor emission level for new sources, but determined
that it would not be cost-effective.
For the final rule, we do not consider a beyond-the-floor level for
new cement kilns because the MACT floor for new cement kilns is already
lower than the beyond-the-floor emission standard for existing sources.
As a result, a beyond-the-floor standard for new cement kilns is not
warranted due to the likely significant costs of control and the
minimal incremental emissions reductions. In addition, our policy goal
of state of the art control of lead is achieved at the floor standard
for new sources. We, therefore, adopt a semivolatile metal floor
standard of 180 g/dscm for new hazardous waste burning cement
kilns.
6. What Are the Low Volatile Metals Standards?
We establish standards for existing and new cement kilns in today's
rule that limit low volatile metal emissions to 56 and 54 g/
dscm, respectively. The rationale for these standards is discussed
below.
a. What Is the MACT Floor tor Existing Sources? In the April 1996
NPRM, we defined floor control as either: (1) A fabric filter with an
air-to-cloth ratio less than 2.3 acfm/ft \2\ and a hazardous waste
feedrate level of 140,000 g/dscm, expressed as a maximum
theoretical emission concentration; or (2) an electrostatic
precipitator with a specific collection area of 350 ft \2\/kacfm and
the same hazardous waste feedrate level of 140,000 g/dscm. The
proposed floor level was 130 g/dscm. (See 61 FR at 17396.) In
the May 1997 NODA, we used a breakpoint analysis to identify sources
that were not using floor control with respect either to low volatile
metals hazardous waste feedrate or emissions control. Under this
approach, we ranked low volatile metals emissions data from sources
that were achieving the particulate matter floor of 69 mg/dscm or
better. We identified the floor level as the test condition average
associated with the breakpoint source. Thus, sources with atypically
high emissions because of high low volatile metals feedrates or poor
low volatile metals control, even though they were using floor control
for particulate matter, were screened from the pool of sources used to
define the floor emission level. The May 1977 NODA MACT floor level was
63 g/dscm. (See 62 FR at 24229.)
We received limited comments in response to the NPRM and May 1997
NODA concerning the low volatile metals floor standard. We received
comments, however, on several overarching issues including the
appropriateness of considering feedrate control of metals including low
volatile metals in hazardous waste as a MACT floor control technique
and the specific procedure of identifying breakpoints in arrayed
emissions data. These issues and our responses to them are discussed in
the floor methodology section in Part Four, Section V.
Today we use a revised engineering evaluation and data analysis
method to establish the MACT floor for low volatile metals on the same
underlying data previously noticed for comment. As explained earlier,
the aggregate feedrate approach, in conjunction with floor control for
particulate matter, replaces the breakpoint analysis for metals and
results in a low volatile metal floor emission level of 56 g/
dscm.
We estimate that over 76 percent of cement kilns in our data base
meet the floor level. The national annualized compliance cost for
cement kilns to reduce low volatile metal emissions to comply with the
floor level is $0.8 million for the entire hazardous waste burning
cement industry, and will reduce low volatile metal emissions by 0.2
Mg/yr or approximately 25 percent from current baseline emissions.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the proposal, we considered a beyond-the-floor standard for
low volatile metals based on improved particulate matter control.
However, we concluded that a beyond-the-floor standard would not likely
be cost-effective based on the limited emissions reductions of low
volatility metals. In the May 1997 NODA, we considered a lower
particulate matter emissions level, based on improved particulate
matter control, as a beyond-the-floor standard with corresponding
beyond-the-floor reductions in low volatile and semivolatile metals.
Even though we did not quantify cost-effectiveness values, we expressed
concern that a beyond-the-floor standard would not likely be cost-
effective. (62 FR at 24229.)
For today's final rule, we identified three potential beyond-the-
floor techniques for control of low volatile metals: (1) Improved
particulate matter control; (2) limiting the feedrate of low volatile
metals in the hazardous waste; and (3) limiting the feedrate of low
volatile metals in the raw materials. We discuss the results of our
analysis of each option below.
Improved Particulate Matter Control. Our judgment is that a beyond-
the-floor standard based on improved particulate matter control would
be less cost-effective than a beyond-the-floor standard based on
limiting the feedrate of low volatile metals in the hazardous waste.
First, our data show that all cement kilns are already achieving
greater than a 99% system removal efficiency for low volatile metals,
with most attaining 99.99% removal. Thus, equipment retrofit costs for
improved control would be significant and result in only a small
increment in reduction of emissions. Our beyond-the-floor analysis for
semivolatile metals supports this conclusion. There, the semivolatile
metals analysis showed that the beyond-the-floor option based on
limiting the feedrate of semivolatile metals was approximately 30% more
cost-effective than a beyond-the-floor option based on improved
particulate matter control. We believe the low volatile metals would
require similar particulate matter control device retrofits at cement
kilns as for semivolatile metals. However, the total emissions
reduction achieved would be less because hazardous waste burning cement
kilns emit less low volatile metals than semivolatile metals. We do not
have any of the serious concerns present for semivolatile metals that
suggest we should accept a more marginal cost-effectiveness. Thus, we
conclude that a beyond-the-floor standard for low volatile metals based
on improved particulate matter control is not warranted.
Limiting the Feedrate of Low Volatile Metals in the Hazardous
Waste. We also considered a beyond-the-floor standard of 40 g/
dscm for low volatile metals based on additional feedrate control of
low volatile metals in the hazardous waste. This would reduce the floor
emission level by approximately 30 percent. Our investigation shows
that this beyond-the-floor option would achieve an incremental
reduction in low volatile metals of only 0.1 Mg/yr. Given that this
beyond-the-floor level would not achieve appreciable emissions
reductions, we conclude that cost-effectiveness considerations would
likely come into play suggesting that this beyond-the-floor standard is
not warranted.
[[Page 52884]]
Limiting the Feedrate of Low Volatile Metals in the Raw Materials.
Sources can achieve a reduction in low volatile metal emissions by
substituting a feed material containing lower levels of arsenic,
beryllium, and/or chromium for a primary raw material with higher
levels of these metals. We believe that this beyond-the-floor option
would be even less cost-effective than either of the options evaluated
above, however. Cement kilns are sited proximate to primary raw
material supply and transporting large quantities of an alternative
source of raw material(s) is likely to be cost-prohibitive. Therefore,
we do not adopt a low volatile metal beyond-the-floor standard based on
limiting the feedrate of low volatile metals in raw materials.
For the reasons discussed above, we do not adopt a beyond-the-floor
level for low volatile metals and establish the emission standard for
existing hazardous waste burning cement kilns at 56 g/dscm.
c. What Is the MACT Floor for New Sources? In the proposal, we
defined floor control as a fabric filter with an air-to-cloth ratio
less than 2.3 acfm/ft2 and a hazardous waste feedrate
control level of 25,000 g/dscm, expressed as a maximum
theoretical emission concentration. The proposed floor for new cement
kilns was 44 g/dscm. (61 FR at 17400.) In the May 1997 NODA,
we concluded that the floor control and emission level for existing
sources for low volatile metals would also be appropriate for new
sources. Floor control was based on a combination of good particulate
matter control and limiting hazardous waste feedrate of low volatile
metals. We used a breakpoint analysis of the low volatile metal
emissions data to exclude sources achieving substantially poorer low
volatile metal control than the majority of sources. We established the
floor level at the test condition average of the breakpoint source. The
NODA floor was 63 g/dscm. (62 FR at 24230.)
As discussed above for existing sources, in developing the final
rule we use the aggregate feedrate approach to identify MACT floors for
the metals and hydrochloric acid/chlorine gas in combination with MACT
floor control for particulate matter. Based on the low volatile metal
feedrate in hazardous waste from the single best performing cement kiln
using floor control for particulate matter, the MACT floor for new
hazardous waste burning cement kilns is 54 g/dscm.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the proposal and May 1997 NODA, we considered a low volatile metal
beyond-the-floor level for new sources, but determined it would not be
cost effective. For reasons similar to those discussed for existing
sources, we do not believe that a beyond-the-floor standard is
warranted for new cement kilns due to the high expected compliance cost
and relatively low reductions in emissions of low volatile metals.
Therefore, we adopt a low volatile metals standard of 54 g/
dscm for new hazardous waste burning cement kilns.
7. What Are the Hydrochloric Acid and Chlorine Gas Standards?
In today's rule, we establish standards for existing and new cement
kilns that limit hydrochloric acid and chlorine gas emissions to 130
and 86 ppmv, respectively. The rationale for these standards is
discussed below.
a. What Is the MACT Floor for Existing Sources? In the proposal, we
identified floor control for hydrochloric acid/chlorine gas as feedrate
control of chlorine in the hazardous waste and proposed a floor
standard of 630 ppmv. (61 FR at 17396.) In the May 1997 NODA, we used a
data analysis method similar to that at proposal and discussed a floor
emission level of 120 ppmv. (62 FR at 24230.)
Some commenters to the May 1997 NODA expressed concern that cement
kilns may not be able to meet the hydrochloric acid/chlorine gas
standard while making low alkali cement. Commenters noted that chlorine
is sometimes added specifically to volatilize potassium and sodium
compounds that must be removed to produce low alkali cement. One
commenter manufacturing a low alkali cement submitted data showing a
large range in hydrochloric acid/chlorine gas emissions while operating
under varying conditions and production requirements. This commenter
stated that they may not be able to meet the NODA hydrochloric acid/
chlorine gas standard of 120 ppmv while making low alkali cement. We
conclude, however, that the data they submitted do not adequately
support this ultimate conclusion. The commenter's emissions data range
from 6 ppmv to 83 ppmv while operating under RCRA compliance testing
conditions. These emission levels are well below the final standard of
130 ppmv, and the expected operational range in this rule is 70% of the
standard. We conclude that the hydrochloric acid/chlorine gas standard
of 130 ppmv finalized today is readily achievable by all cement kilns
irrespective of the type of cement manufactured.
For today's rule, we use a revised engineering evaluation and data
analysis method to establish the MACT floor for hydrochloric acid and
chlorine gas on the same underlying data previously noticed for
comment. Using the aggregate feedrate approach discussed previously, we
establish a hydrochloric acid/chlorine gas floor emission level of 130
ppmv.
We estimate that approximately 88 percent of cement kilns in our
data base currently meet the floor level. The national annualized
compliance cost for cement kilns to reduce hydrochloric acid/chlorine
gas emissions to comply with the floor level is $1.4 million for the
entire hazardous waste burning cement industry and will reduce
hydrochloric acid/chlorine gas emissions by 383 Mg/yr or 12 percent
from current baseline emissions.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the proposal, we defined beyond-the-floor control as wet
scrubbing with a 99 percent removal efficiency, but determined that a
beyond-the-floor standard would not be cost-effective. (61 FR at
17397.) In the May 1997 NODA, we identified a more stringent floor
standard and therefore reasoned that a beyond-the-floor standard based
on wet scrubbing would likely also not be cost-effective. (62 FR at
24230.)
For today's rule, we identified three potential beyond-the-floor
techniques for control of hydrochloric acid/chlorine gas emissions: (1)
Scrubbing; (2) limiting the feedrate of chlorine in the hazardous
waste; and (3) limiting the feedrate of chlorine in the raw materials.
We discuss our analysis of each option below.
Scrubbing. We continue to believe that a beyond-the-floor standard
based on dry or wet scrubbing is not likely to be cost-effective.
Cement kilns achieve control of hydrochloric acid/chlorine gas
emissions from alkaline raw materials in the kiln. Control
effectiveness varies among kilns based on the alkalinity of the raw
materials. Thus, the cement manufacturing process serves essentially as
a dry scrubber. We conclude, therefore, that the addition of a dry
scrubber will only marginally improve hydrochloric acid/chlorine gas
removal and is not warranted as beyond-the-floor control.
It is also our judgment that a beyond-the-floor standard based on
wet scrubbing is not warranted. The total estimated engineering
retrofit costs would be approximately equivalent to those identified at
proposal for this option. However, emissions reductions would be less
given that the final MACT floor level is more stringent than the
[[Page 52885]]
level proposed. Therefore, the cost-effectiveness of a beyond-the-floor
standard would be less attractive than the number we rejected at
proposal. As a result, we must reaffirm that conclusion here.
Limiting the Feedrate of Chlorine in the Hazardous Waste. We also
considered a beyond-the-floor standard for hydrochloric acid/chlorine
gas based on additional feedrate control of chlorine in the hazardous
waste. We are concerned, however, that cement kilns making low alkali
cement may not be able to achieve a beyond-the-floor standard by
controlling feedrate of chlorine in the hazardous waste. As noted
above, chlorine is sometimes added specifically to volatilize potassium
and sodium compounds that must be removed from the clinker to produce
low alkali cement. Based on limited data submitted by a cement facility
manufacturing low alkali cement, achievability of a beyond-the-floor
standard of 70 ppmv, representing a 45% reduction from the floor level,
may not be feasible for this source using feedrate control and others
by inference. Therefore, we conclude that a beyond-the-floor standard
based on chlorine feedrate control in the hazardous waste is not
appropriate.
Limiting the Feedrate of Chlorine in the Raw Materials. A source
can achieve a reduction in hydrochloric acid/chlorine gas emissions by
substituting a feed material containing lower levels of chlorine for a
primary raw material with higher levels of chlorine. This beyond-the-
floor option is less cost-effective compared to the scrubbing options
evaluated above because cement kilns are sited proximate to the primary
raw material supply and transporting large quantities of an alternative
source of raw material(s) is not technically achievable. Therefore, we
do not adopt a hydrochloric acid/chlorine gas beyond-the-floor standard
based on limiting the feedrate of chlorine in raw materials.
In summary, we establish the hydrochloric acid/chlorine gas
standard for existing hazardous waste burning cement kilns at the floor
level of 130 ppmv.
c. What Is the MACT Floor for New Sources? At proposal, we defined
floor control for new sources as hazardous waste feedrate control for
chlorine and the proposed floor level was 630 ppmv. (See 61 FR at
17401.) In the May 1997 NODA, we concluded that the floor control and
emission level for existing sources for hydrochloric acid/chlorine gas
would also be appropriate for new sources. Floor control was based on
limiting hazardous waste feedrates of chlorine. After screening out
some data with anomalous system removal efficiencies compared to the
majority of sources, we established the floor level at the test
condition average of the breakpoint source. We identified a floor level
for new kilns of 120 ppmv. (See 62 FR at 24230.)
As discussed above for existing sources, in developing the final
rule, we use the aggregate feedrate approach to identify MACT floors
for hydrochloric acid/chlorine gas. The resulting MACT emissions floor
for new hazardous waste burning cement kilns is 86 ppmv.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the proposal, we considered a beyond-the-floor standard for new cement
kilns of 67 ppmv based on wet scrubbing and concluded that it would not
be cost-effective. In the May 1997 NODA, we also concluded that a
beyond-the-floor standard based on wet scrubbing would likewise not be
cost-effective. Considering the level of the floor standard for new
kilns, we do not believe that a more stringent beyond-the-floor
standard is warranted for the final rule, especially considering our
concerns for cement kilns manufacturing low alkali cements.
In summary, we adopt the floor level of 86 ppmv as the standard for
hydrochloric acid/chlorine gas for new sources.
8. What Are the Hydrocarbon and Carbon Monoxide Standards for Kilns
Without By-Pass Sampling Systems? 138
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\138\ See USEPA, ``Final Technical Support Document for
Hazardous Waste Combustor MACT Standards, Volume I: Description of
Source Categories,'' July 1999, for further explanation of by-pass
and midkiln sampling systems. Hydrocarbon and carbon monoxide
standards for kilns equipped with by-pass sampling systems are
discussed in Section VI.D.9 f the text.
---------------------------------------------------------------------------
See Sec. 63.1205(a)(5) and (b)(5).
In today's rule, we establish hydrocarbon and carbon monoxide
standards for new and existing cement kilns without by-pass sampling
systems as surrogates to control emissions of nondioxin organic
hazardous air pollutants. The standards for existing sources limit
hydrocarbon or carbon monoxide concentrations to 20 ppmv \139\ or 100
ppmv, \140\ respectively. The standards for new sources limit: (1)
Hydrocarbons to 20 ppmv; or (2) carbon monoxide to 100. New, greenfield
\141\ kilns that elect to comply with the 100 ppmv carbon monoxide
standard, however, must also comply with a 50 ppmv \142\ hydrocarbon
standard. New and existing sources that elect to comply with the 100
ppmv carbon monoxide standard, including new greenfield kilns that
elect to comply with the carbon monoxide standard and 50 ppmv
hydrocarbon standard, must also demonstrate compliance with the 20 ppmv
hydrocarbon standard during the comprehensive performance test.\143\
(See Part Four, Section IV.B of the preamble for the rationale for this
requirement.) We discuss the rationale for these standards below.
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\139\ Hourly rolling average, reported as propane, dry basis,
and corrected to 7% oxygen.
\140\ Hourly rolling average, dry basis, corrected to 7% oxygen.
\141\ A greenfield cement kiln is a kiln that commenced
construction or reconstruction after April 19, 1996 at a site where
no cement kiln previously existed, irrespective of the class of kiln
(i.e., nonhazardous waste or hazardous waste burning). A newly
constructed or reconstructed cement kiln at an existing site would
not be classified as a greenfield cement kiln, and would be subject
to the same carbon monoxide and hydrocarbon standards as an existing
cement kiln.
\142\ Thirty day block average, reported as propane, dry basis,
and corrected to 7 percent oxygen.
\143\ As discussed in Part 5, Section X.F, sources that feed
hazardous waste at a location other than the end where products are
normally discharged and where fuels are normally fired must comply
with the 20 ppmv hydrocarbon standard i.e., these sources do not
have the option to comply with the carbon monoxide standard).
---------------------------------------------------------------------------
a. What Is the MACT Floor for Existing Sources? As discussed in
Part Four, Section II.B.2, we proposed limits on hydrocarbon emissions
for kilns without by-pass sampling systems as a surrogate to control
nondioxin organic hazardous air pollutants. In the April 1996 proposal
(61 FR at 17397), we identified a hydrocarbon floor emission level of
20 ppmv for cement kilns not equipped with by-pass sampling systems,
and proposed that floor control be based on the current federally-
enforceable RCRA boiler and industrial furnace standards, control of
organics in raw materials coupled with operating under good combustion
practices to minimize fuel-related hydrocarbon. In the May 1997 NODA,
we also indicated that this approach was appropriate.
Some commenters stated that a carbon monoxide limit of 100 ppmv was
necessary for these cement kilns to better control organic hazardous
air pollutants. Commenters also wrote that, alone, neither carbon
monoxide nor hydrocarbons is an acceptable surrogate for organic
hazardous air pollutant emissions. Additionally, commenters suggested
that by requiring both carbon monoxide and hydrocarbon limits, we would
further reduce emissions of organic hazardous air pollutants.
We conclude that continuous compliance with both a carbon monoxide
and hydrocarbon standard is unwarranted for the following reasons.
First, stack gas carbon monoxide levels are not a universally reliable
indicator
[[Page 52886]]
of combustion intensity and efficiency for kilns without by-pass
sampling systems. This is due to carbon monoxide generation by
disassociation of carbon dioxide to carbon monoxide at the high
sintering zone temperatures and evolution of carbon monoxide from the
trace organic constituents in raw material feedstock.\144\ (See 56 FR
at 7150, 7153-55). Thus, carbon monoxide can be a too conservative
surrogate for this type of kiln for potential emissions of hazardous
air pollutants from combustion of hazardous waste. There are other
sources of carbon monoxide unrelated to combustion of hazardous
waste.\145\
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\144\ Raw materials enter the upper end of the kiln and move
counter-current to the combustion gas. Thus, as the raw materials
are heated in the kiln, organic compounds can evolve from trace
levels of organics in the raw materials. These organic compounds can
be measured as hydrocarbons and, when only partially oxidized,
carbon monoxide. This process is not related to combustion of
hazardous waste or other fuels in the combustion zone at the other
end of the kiln.
\145\ Of course, if a source elects to comply with the carbon
monoxide standard, then we are more assured of good combustion
conditions in the combustion zone, and thus good control of organic
hazardous air pollutants that could be potentially emitted from
feeding hazardous waste in the combustion zone.
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Second, requiring continuous compliance with both a carbon monoxide
and hydrocarbon emission limitation in the stack can be redundant for
control of organic emissions from combustion of hazardous waste
because: (1) Hydrocarbon alone is a direct and reliable surrogate for
organic hazardous air pollutants; and (2) in most cases carbon monoxide
is a conservative indicator of good combustion conditions and thus good
control of organic hazardous air pollutants. As discussed in the
following paragraphs, however, we have concluded that a source must
demonstrate compliance with the hydrocarbon standard during the
comprehensive performance test if it elects to continuously comply with
the carbon monoxide standard to ensure that carbon monoxide is an
adequate continuously monitored indicator of combustion efficiency. See
Part Four, Section IV of the preamble for a discussion of the merits of
using limits on stack gas concentrations of carbon monoxide and
hydrocarbon to control organic emissions.
One commenter suggested cement kilns be given the option to comply
with a carbon monoxide limit of 100 ppmv instead of the 20 ppmv
hydrocarbon limit. The commenter emphasized that this option is
currently allowed under the RCRA boiler and industrial furnace
regulations, and that it would be conservative because hydrocarbon
levels would always be below 20 ppmv when carbon monoxide levels are
below 100 ppmv. As discussed below, we agree that cement kilns should
be given the option to comply with either standard, but do not agree
that compliance with the carbon monoxide standard ensures compliance
with the hydrocarbon standard.
We have determined that it is necessary to require a source that
elects to continuously comply with the carbon monoxide standard to also
demonstrate compliance with the 20 ppmv hydrocarbon standard during the
comprehensive performance test. We concluded that this requirement is
necessary because we have limited data that shows a source can produce
high hydrocarbon emissions while simultaneously producing low carbon
monoxide emissions. This requirement to demonstrate compliance with the
hydrocarbon standard during the performance test is sufficient to
ensure that carbon monoxide alone is an appropriate continuously
monitored indicator of combustion efficiency. See Part 4, Section IV.B,
for a more detailed discussion. Consistent with this principle,
incinerators and lightweight aggregate kilns are also required to
demonstrate compliance with hydrocarbon standard during the
comprehensive performance test if they elect to comply with the carbon
monoxide standard.
In today's final rule, we are identifying a carbon monoxide level
of 100 ppmv and a hydrocarbon level of 20 ppmv as floor control for
existing sources because they are currently enforceable Federal
standards for hazardous waste burning cement kilns. See Sec. 266.104(b)
and (c). As current rules allow, sources would have the option of
complying with either limit. However, sources that elect to comply with
the carbon monoxide standard must also demonstrate compliance with the
hydrocarbon standard during the comprehensive performance test.
Given that these are current RCRA rules, all cement kilns without
by-pass sampling systems can currently achieve these emission levels.
Thus, we estimate no emissions reductions (or new costs) for compliance
with these floor levels.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the April 1996 proposal, we identified beyond-the-floor
control levels for carbon monoxide and hydrocarbon in the main stack of
50 ppmv and 6 ppmv, respectively. (See 61 FR at 17397.) These beyond-
the-floor levels were based on the use of a combustion gas afterburner.
We indicated in the proposal, however, that the beyond-the-floor
control was not practical since no kilns currently achieved these
emission levels, and because of the high costs to retrofit a kiln with
an afterburner.
One commenter wrote that we rejected the 50 ppmv and 6 ppmv beyond-
the-floor carbon monoxide and hydrocarbon standards, respectively,
without providing any justification. In order to confirm the reasoning
discussed above, we have now estimated that the annualized cost for an
afterburner for cement kilns will range from $3-8 million dollars per
facility.\146\ As proposed, and as we reiterated in the May 1997 NODA a
beyond-the-floor standard based on an afterburner would be not be cost-
effective due to the high retrofit costs and minimal incremental
emissions reductions, and we do not adopt a beyond-the-floor standard
for existing cement kilns.
---------------------------------------------------------------------------
\146\ See `Final Technical Support Document for Hazardous Waste
Combustor MACT Standards, Volume V: Emission Estimates and
Engineering Costs'', February, 1999.
---------------------------------------------------------------------------
In summary, we adopt the floor emission levels as standards for
carbon monoxide, 100 ppmv, and hydrocarbons, 20 ppmv.
c. What Is the MACT Floor for New Sources? In the April 1996
proposal (see 61 FR at 17401) and the May 1997 NODA, we identified a
new source hydrocarbon floor emission level of 20 ppmv for new cement
kilns not equipped with by-pass sampling systems based on the current
Federally-enforceable BIF standards. The hydrocarbon limit is based on
control of organics in raw materials coupled with good combustion
practices.
In developing the final rule, we considered the comment discussed
above that the rule should allow compliance with either a carbon
monoxide standard of 100 ppmv or a hydrocarbon standard of 20 ppmv.
Given that this option is available under the current BIF rule for new
and existing sources, we now conclude that it represents MACT floor for
new sources, except as discussed below.
As discussed previously, we have also proposed MACT standards for
nonhazardous waste burning cement kilns. See 63 FR 14182, March 24,
1998. In that proposal, we determined that some existing sources have
used the combination of feed material selection, site location, and
feed material blending to optimize operations. We then concluded that
site selection based on availability of acceptable raw material
hydrocarbon content is a feasible approach to control hydrocarbon
emissions at new sources. See 63 FR at 14202-03. We proposed a new
source
[[Page 52887]]
floor hydrocarbon emission level of 50 ppmv at nonhazardous waste
burning Portland cement kilns because it is being consistently achieved
during thirty-day block averaging periods when high hydrocarbon content
raw materials are avoided. We have since promulgated a standard of 50
ppmv for hydrocarbons for new nonhazardous waste burning cement kilns.
64 FR 31898.
We now conclude for the same reasons that site selection is floor
control for new source, greenfield hazardous waste burning cement kilns
\147\ and that the floor hydrocarbon emission level is 50 ppmv.\148\
Sources must document compliance with this standard for each thirty-day
block period of operation. We reconcile this hydrocarbon floor level of
50 ppmv with the floor levels discussed above of 20 ppmv hydrocarbons
or 100 ppmv carbon monoxide by establishing the floor as follows. For
new source greenfield kilns, the floor is either: (1) 20 ppmv
hydrocarbons; or (2) 100 ppmv carbon monoxide and 50 ppmv hydrocarbons.
For other new sources not located at greenfield sites, the floor is
either 20 ppmv hydrocarbons or 100 ppmv carbon monoxide, which is
identical to the standards for existing sources.
---------------------------------------------------------------------------
\147\ At least one hazardous waste burning cement kiln in our
data base used raw material substitution to control hydrocarbon
emissions.
\148\ We concluded that this new source hydrocarbon standard of
50 ppms should not apply to new sources that are not located at
greenfield sites since these kilns are not capable of using site-
selection to control hydrocarbon emissions.
---------------------------------------------------------------------------
The combined 20 ppmv hydrocarbon and 100 ppmv carbon monoxide
standards control organic hazardous air pollutant emissions that
originate from the incomplete combustion of hazardous waste. The 50
ppmv hydrocarbon standard for new greenfield kilns controls organic
hazardous air pollutant emissions that originate from the raw material.
We conclude that the 50 ppmv hydrocarbon standard is necessary to deter
new kilns from siting at locations that have on-site raw material that
is high in organic content, since siting a cement kiln at such a
location could result in elevated hydrocarbon emissions.
We considered whether new greenfield kilns would be required to
monitor hydrocarbons continuously, or just document compliance with the
50 ppmv limit during the comprehensive performance test. We determined
that hydrocarbons must be continuously monitored because compliance
with the 100 ppmv carbon monoxide limit may not always ensure
compliance with the 50 ppmv hydrocarbon limit. This is because
hydrocarbons could potentially evolve from raw materials in the upper
drying zone end of the kiln under conditions that inhibit sufficient
oxidation of the hydrocarbons to form carbon monoxide.
As with existing sources, we are requiring new sources that elect
to continuously comply with the carbon monoxide standard, and new
greenfield sources that elect to comply with the carbon monoxide and 50
ppmv hydrocarbon standard, to also demonstrate compliance with the 20
ppmv hydrocarbon standard during the comprehensive performance test.
Consistent with this principle, incinerators and lightweight aggregate
kilns are also required to demonstrate compliance with the hydrocarbon
standard during the comprehensive performance test if they elect to
comply with the carbon monoxide standard.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the April 1996 proposal, we identified beyond-the-floor emission levels
for carbon monoxide and hydrocarbon of 50 ppmv and 6 ppmv,
respectively, for new sources. (See 61 FR at 17401.) These beyond-the-
floor levels were based on the use of a combustion gas afterburner. We
indicated in the proposal, however, that beyond-the-floor control was
not practical since none of the kilns in our data base are achieving
these emission levels, and because of the high costs to retrofit kilns
with an afterburner. We reiterated in the May 1997 NODA that a beyond-
the-floor standard based on use of an afterburner would not be cost-
effective.
One commenter supported these beyond-the-floor standards for new
sources, but did not explain why these were considered to be
appropriate standards. As discussed above for existing sources, we
continue to believe that a beyond-the-floor standard based on use of an
afterburner would not be cost-effective.
In summary, we adopt the floor levels as standards for new sources.
For new source greenfield kilns, the standard monitored continuously is
either: (1) 20 ppmv hydrocarbons; or (2) 100 ppmv carbon monoxide and
50 ppmv hydrocarbons. For other new source kilns, the standard is
either 20 ppmv hydrocarbons or 100 ppmv carbon monoxide monitored
continuously. New sources that elect to comply with the carbon monoxide
standard, and new greenfield sources that elect to comply with the
carbon monoxide and 50 ppmv hydrocarbon standard, must also demonstrate
compliance with the 20 ppmv hydrocarbon standard, but only during the
comprehensive performance test.
9. What Are the Carbon Monoxide and Hydrocarbon Standards for Kilns
With By-Pass Sampling Systems? 149
---------------------------------------------------------------------------
\149\ This also includes cement kilns which have midkiln
sampling systems. See USEPA, ``Final Technical Support Document for
Hazardous Waste Combustor MACT Standards, Volume I: Description of
Source Categories,'' July 1999, for further explanation of by-pass
and midkiln sampling systems.
---------------------------------------------------------------------------
See Sec. 63.1204(a)(5) and (b)(5).
We establish carbon monoxide and hydrocarbon standards for existing
and new cement kilns with by-pass sampling systems as surrogates to
control emissions of nondioxin organic hazardous air
pollutants.150 Existing kilns are required to comply with
either a carbon monoxide standard of 100 ppmv or a hydrocarbon standard
of 10 ppmv on an hourly rolling average basis. Both standards apply to
combustion gas sampled in the by-pass or a midkiln sampling port that
samples representative kiln gas. Sources that elect to comply with the
carbon monoxide standard, however, must also document compliance with
the hydrocarbon standard during the comprehensive performance
test.151 See Part Four, Section IV.B of the preamble for the
rationale for this requirement.
---------------------------------------------------------------------------
\150\ As discussed in Part 5, Section X.F, cement kilns equipped
with bypass sampling systems that feed hazardous waste at a location
other than the end where products are normally discharged and at a
location downstream of the bypass sampling location (relative to the
combustion gas flow direction) must comply with the 20 ppmv main
stack hydrocarbon standard discussed in the previous section in lieu
of the bypass gas hydrocarbon standard.
\151\As discussed in Part 5, Section X.F, cement kilns that feed
hazardous waste at a location other than the end where products are
normally discharged and where fuels are normally fired must comply
wit the 10 ppmv hydrocarbon standard (i.e., these sources do not
have the option to comply with the carbon monoxide standard).
---------------------------------------------------------------------------
New kilns are subject to the same by-pass gas carbon monoxide and
hydrocarbon standards as existing sources. But, new, greenfield
152 kilns must also comply with a 50 ppmv hydrocarbon
standard continuously monitored in the main stack. Sources must
document compliance with this standard for each thirty-day block period
of operation.
---------------------------------------------------------------------------
\152\ A greenfield cement kiln is a kiln that commenced
construction or reconstruction after April 19, 1996 at a site where
no cement kiln previously existed, irrespective of the class of kiln
(i.e., nonhazardous waste or hazardous waste burning). A newly
constructed or reconstructed cement kiln at an existing site would
not be classified as a greenfield cement kiln, and would be subject
to the same carbon monoxide and hydrocarbon standards as an existing
cement kiln.
---------------------------------------------------------------------------
We discuss the rationale for adopting these standards below.
[[Page 52888]]
a. What Is the MACT Floor for Existing Sources? In the April 1996
proposal, we identified floor carbon monoxide and hydrocarbon emission
standards for by-pass gas of 100 ppmv and 6.7 ppmv, respectively. Floor
control was good combustion practices. (See 61 FR at 17397.) In the May
1997 NODA, we used an alternative data analysis method to identify a
hydrocarbon floor level of 10 ppmv.153 See 62 FR at 24230.
Our decision to use engineering information and principles to set the
proposed floor standard was based, in part, on the limited hydrocarbon
data in our data base. In addition, we reasoned that the hydrocarbon
levels being achieved in an incinerator, (i.e., 10 ppmv) are also being
achieved in a cement kiln's by-pass duct.154
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\153\ The proposed hydrocarbon standard of 6.7 ppmv was based on
a statistical and breakpoint analysis. Today's final rule,
consistent with May 1997 NODA, instead uses engineering information
and principles to identify the floor hydrocarbon level of 10 ppmv.
\154\ See USEPA, ``Final Technical Support Document for
Hazardous Waste Combustor MACT Standards, Volume III: Selection of
MACT Standards and Technologies,'' February, 1999.
---------------------------------------------------------------------------
Some commenters stated that we did not have sufficient hydrocarbon
emissions data from cement kilns equipped with by-pass sampling systems
to justify a by-pass duct hydrocarbon standard. We disagree and
conclude that we have adequate data because the MACT data base includes
seven cement kilns that monitored hydrocarbons at the bypass sampling
location. These sources are achieving hydrocarbon levels of 10 ppmv or
less.155 The fact that these sources achieve hydrocarbon
levels below 10 ppmv supports our use of engineering information and
principles to set the floor limit at 10 ppmv.156
---------------------------------------------------------------------------
\155\ Four of these kilns have ceased hazardous waste
operations, and one of the kilns collected that data during time
periods other than Certification of Compliance testing.
\156\ We note that we could have elected to establish this 10
ppmv hydrocarbon standard as a beyond-the-floor standard rather than
a floor standard.
---------------------------------------------------------------------------
Many commenters questioned whether cement kilns with by-pass
sampling systems should comply with both a hydrocarbon and carbon
monoxide standard. Those in favor of requiring cement kilns to comply
with both standards wrote that neither carbon monoxide nor hydrocarbons
are sufficient surrogates for organic hazardous air pollutant
emissions. Commenters also noted that by requiring both a carbon
monoxide and hydrocarbon limit, we would achieve appropriate organic
hazardous air pollutant emission reductions. Other commenters wrote
that continuous compliance with both a hydrocarbon and a carbon
monoxide standard would be redundant and unnecessarily costly. We agree
with the latter view, in that requiring continuous compliance with both
standards for bypass gas is redundant for control of organic emissions
from combustion of hazardous waste because, as previously discussed:
(1) Hydrocarbon alone is a direct and reliable surrogate for organic
hazardous air pollutants; and (2) in most cases, carbon monoxide is a
conservative indicator of good combustion conditions and thus good
control of organic hazardous air pollutants. However, as discussed
earlier, we have concluded that a source must demonstrate compliance
with the hydrocarbon standard during the comprehensive performance test
if it elects to continuously comply with the carbon monoxide standard
to ensure that carbon monoxide is an adequate continuously monitored
indicator of combustion efficiency. See discussion in Part Four,
Section IV.B of the preamble for more discussion on this issue.
One commenter stated that due to some by-pass gas quenching
methods, and the need to correct for moisture and oxygen, it may not be
possible to accurately measure hydrocarbons to the level of the
proposed standard, i.e., 6.7 ppmv. We disagree with this reasoning
because, as explained in the technical support document, cement kiln
by-pass hydrocarbon levels should be reasonably achievable and
measurable by decreasing the span and increasing the calibration
frequency of the hydrocarbon monitor.157 We also note that a
cement kiln has the option to petition the Administrator for
alternative monitoring approaches under Sec. 63.8(f) if the source has
valid reasons why a total hydrocarbon monitor cannot be used to
document compliance.
---------------------------------------------------------------------------
\157\ See USEPA, ``Final Technical Support Document for
Hazardous Waste Combustor MACT Standards, Volume III: Selection of
MACT Standards and Technologies,'' February, 1999.
---------------------------------------------------------------------------
We conclude that floor control can achieve by-pass gas emission
levels of 100 ppmv for carbon monoxide and 10 ppmv for hydrocarbons. As
discussed in Part Four, Section IV.B, a source may comply with either
standard. If the source elects to comply with the carbon monoxide
standard, however, it must also demonstrate compliance with the
hydrocarbon standard during comprehensive performance testing.
We estimate that all cement kilns with by-pass sampling systems can
currently achieve the carbon monoxide floor of 100 ppmv. We also
estimate that approximately 97 percent of cement kilns with by-pass
sampling systems meet the hydrocarbon floor level of 10 ppmv. The
national annualized compliance cost for cement kilns to comply with the
floor level is $37K and hydrocarbon emissions will be reduced by 11 Mg/
yr, two percent from current baseline emissions .
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the April 1996 proposal, we identified a beyond-the-floor
control level for carbon monoxide and hydrocarbons in the main stack of
50 ppmv and 6 ppmv, respectively, based on the use of a combustion gas
afterburner. (See 61 FR at 17399.) We indicated in the proposal that
this beyond-the-floor level was not practical, however, since none of
the kilns currently achieve these emission levels and because of the
high costs of retrofitting kilns with an afterburner. We estimate that
the annualized cost for each cement kiln to operate afterburners range
from three to eight million dollars.158 We continue to
believe that it is not cost-effective based on the high retrofit costs
and minimal incremental emissions reductions to adopt these beyond-the-
floor standards.
---------------------------------------------------------------------------
\158\ See ``Final Technical Support Document for Hazardous Waste
Combustor MACT Standards, Volume V: Emission Estimates and
Engineering Costs'', February, 1999.
---------------------------------------------------------------------------
In the April 1996 NPRM, we also considered limiting main stack
hydrocarbon emissions to a beyond-the-floor level of 20 ppmv based on
the use of a low-organic raw material.159 This was in
addition to floor controls limiting carbon monoxide and/or hydrocarbon
levels in the by-pass. See 61 FR at 17398. We considered this beyond-
the-floor option to address concerns that: (1) organics desorbed from
raw materials may contain hazardous air pollutants, even absent any
influence from burning hazardous waste; and, (2) it is reasonable to
hypothesize that the chlorine released from burning hazardous waste can
react with the organics desorbed from the raw material to form
generally more toxic chlorinated hazardous air pollutants. Many
commenters supported this approach. For the reasons discussed below,
however, we conclude it is not appropriate to adopt this beyond-the-
[[Page 52889]]
floor hydrocarbon standard for existing sources.
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\159\ The definition of floor control for existing cement kilns
equipped with by-pass sampling systems does not include the use of
low organic raw material. Although we have limited data indicating
that some kilns used low organic raw material to control hydrocarbon
emissions, there are enough facilities using this method of control
to establish it as a floor control for existing sources.
---------------------------------------------------------------------------
Also, many commenters stated that we should establish a main stack
hydrocarbon standard because, as stated above, hazardous waste
combustion byproducts from cement kilns, particularly chlorine, can
react with organic compounds desorbed from raw materials to form
hazardous air pollutants. Commenters believe that an additional main
stack hydrocarbon emission standard would limit the emissions of
chlorinated organic hazardous air pollutants that are generated due to
the interaction of the hazardous waste combustion byproducts and the
organics desorbed from the raw material.
We disagree that a main stack hydrocarbon emission limit is an
appropriate beyond-the-floor control for existing sources. First, we do
not believe it is cost-effective to require an existing kiln to
substitute its raw material with an off-site raw
material.160 Cement kilns are sited proximate to the primary
raw material supply and transporting large quantities of an alternative
source of raw material(s) is likely to be very costly. Second,
establishing a main stack hydrocarbon limit for existing sources is
likely to be counter-productive in controlling organic hazardous air
pollutants. It may compel the operator to avoid the unacceptable costs
of importing low organic raw material by increasing back-end kiln
temperatures to oxidize organics desorbed from raw material, thus
lowering hydrocarbon levels. This increase in temperature may result in
increased dioxin formation and is counter to our dioxin control
strategy. Third, it is debatable whether there is a strong relationship
between chlorine feedrates and chlorinated organic hazardous air
pollutant emissions, as is suggested by commenters.161
Finally, we anticipate that any potential risks associated with the
possible formation of these chlorinated hazardous air pollutants at
high hydrocarbon emission levels can be adequately addressed in a site-
specific risk assessment conducted as part of the RCRA permitting
process. This increased potential for emissions of chlorinated
hazardous air pollutants is not likely to warrant evaluation via a
site-specific risk assessment under RCRA, however, unless main stack
hydrocarbon levels are substantially higher than the 20 ppmv limit
currently applicable under RCRA for cement kilns not equipped with by-
pass systems.
---------------------------------------------------------------------------
\160\ We did not quantify actual costs associated with raw
material substitution due to the lack of information.
\161\ It is true that some studies have shown a relationship
between chlorine levels in the flue gas and the generation of
chlorobenzene in cement kiln emissions: the more chlorine, the more
chlorobenzene is generated. Some full-scale tests, however, have
shown that there is no observable or consistent trend when comparing
``baseline'' (i.e., nonhazardous waste operation) organic hazardous
air pollutant emissions with organic hazardous air pollutant
emissions associated with hazardous waste operations, as well as
comparing hazardous waste conditions with varying levels of
chlorine. See USEPA, ``Final Technical Support Document for
Hazardous Waste Combustor MACT Standards, Volume III: Selection of
MACT Standards and Technologies,'' July 1999, for further
discussion.
---------------------------------------------------------------------------
In summary, we adopt the floor levels as standards for carbon
monoxide, 100 ppmv, and hydrocarbons, 10 ppmv. As discussed above, a
source may comply with either standard. If the source elects to comply
with the carbon monoxide standard, however, it must also demonstrate
compliance with the hydrocarbon standard during comprehensive
performance testing.
c. What Is the MACT Floor for New Sources? In the April 1996
proposal, we identified new source floor standards for carbon monoxide
and hydrocarbon emissions in the by-pass of 100 ppmv and 6.7 ppmv,
respectively. We identified good combustion practices as floor control.
(See 61 FR at 17401.) In the May 1997 NODA, we used an alternative data
analyses method, in part, to identify an alternative new source
hydrocarbon floor level. (See 62 FR at 24230.) As a result of this
analysis and the use of engineering information and principles, we
identified a floor hydrocarbon emission level of 10 ppmv in the by-pass
for new cement kilns. We continue to believe that the new source
hydrocarbon floor methodology discussed in the May 1997 NODA, and the
new source carbon monoxide floor methodology discussed in the April
1996 proposal, are appropriate. Therefore, we adopt these floor
emission levels for by-pass gas in today's final rule.
We also establish a 50 ppmv hydrocarbon floor level for the main
stack of new greenfield kilns. As discussed above (Part Four, Section
VII.8.c), we concluded during development of the final rule that some
cement kilns are currently controlling their feed material selection,
site location, and feed material blending to optimize operations.
Because these controls can be used to control hydrocarbon content of
the raw material and, thus, hydrocarbon emissions in the main stack,
they represent floor control for main stack hydrocarbons for new
sources.162 We established a floor hydrocarbon emission
level of 50 ppmv because it is being consistently achieved during
thirty-day block averaging periods when high hydrocarbon content raw
materials are avoided.
---------------------------------------------------------------------------
\162\ At least one hazardous waste burning cement kiln in our
data base used raw material substitution to control hydrocarbon
emissions.
---------------------------------------------------------------------------
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the April 1996 proposal, we identified main stack beyond-the-floor
emission levels for carbon monoxide and hydrocarbon of 50 ppmv and 6
ppmv, respectively, for new sources. (See 61 FR at 17401.) These
beyond-the-floor levels were based on the use of a combustion gas
afterburner. We indicated in the proposal, however, that beyond-the-
floor control was not practical since none of the kilns in our data
base are achieving these emission levels, and because of the high costs
to retrofit kilns with an afterburner. We reiterated in the May 1997
NODA, that a beyond-the-floor standard based on use of an afterburner
would not be cost-effective.
One commenter wrote that we rejected these beyond-the-floor carbon
monoxide and hydrocarbon standards without providing any justification.
Another commenter supported these beyond-the-floor standards for new
sources. As discussed above (in greater detail) for existing sources,
we continue to believe that a beyond-the-floor standard based on use of
an afterburner would not be cost-effective.
In the April 1996 proposal, we considered limiting main stack
hydrocarbon emissions at new sources equipped with by-pass sampling
systems to a beyond-the-floor level of 20 ppmv.163 This
addressed concerns that: (1) Organics desorbed from raw materials
contain hazardous air pollutants, even absent any influence from
burning hazardous waste; and (2) it is reasonable to hypothesize that
the chlorine released from burning hazardous waste can react with the
organics desorbed from the raw material to form generally more toxic
chlorinated hazardous air pollutants. Although not explicitly stated,
beyond-the-floor control would have been control of feed material
selection, site location, and feed material blending to control the
hydrocarbon content of the raw material and, thus, hydrocarbon
emissions in the main stack. As discussed above, however, we adopt
today a main stack hydrocarbon floor standard of 50 ppmv for newly
constructed greenfield cement kilns equipped with by-pass systems. We
are not adopting a main stack beyond-the floor hydrocarbon standard of
20 ppmv for these kilns because we
[[Page 52890]]
are concerned that it may not be readily achievable using beyond-the-
floor control.
---------------------------------------------------------------------------
\163\ This was in addition to limiting hydrocarbon and/or carbon
monoxide at the by-pass sampling location.
---------------------------------------------------------------------------
In summary, we establish the following standards for new sources
based on floor control: (1) By-pass gas emission standards for carbon
monoxide and hydrocarbons of 100 ppmv and 10 ppmv, respectively;
164 and (2) a main stack hydrocarbon standard of 50 ppmv at
greenfield sites.
---------------------------------------------------------------------------
\164\ A source may comply with either bypass gas standard. If
the source elects to comply with the carbon monoxide standard,
however, it must also demonstrate compliance with the hydrocarbon
standard during comprehensive performance testing.
---------------------------------------------------------------------------
10. What Are the Destruction and Removal Efficiency Standards?
We establish a destruction and removal efficiency (DRE) standard
for existing and new cement kilns to control emissions of organic
hazardous air pollutants other than dioxins and furans. Dioxins and
furans are controlled by separate emission standards. See discussion in
Part Four, Section IV.A. The DRE standard is necessary, as previously
discussed, to complement the carbon monoxide and hydrocarbon emission
standards, which also control these hazardous air pollutants.
The standard requires 99.99 percent DRE for each principal organic
hazardous constituent (POHC), except that 99.9999 percent DRE is
required if specified dioxin-listed hazardous wastes are burned. These
wastes are listed as--F020, F021, F022, F023, F026, and F027--RCRA
hazardous wastes under part 261 because they contain high
concentrations of dioxins.
a. What Is the MACT Floor for Existing Sources? Existing sources
are currently subject to DRE standards under Sec. 266.104(a) that
require 99.99 percent DRE for each POHC, except that 99.9999 percent
DRE is required if specified dioxin-listed hazardous wastes are burned.
Accordingly, these standards represent MACT floor. Since all hazardous
waste cement kilns are currently subject to these DRE standards, they
represent floor control, i.e., greater than 12 percent of existing
sources are achieving these controls.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? Beyond-the-floor control would be a requirement to achieve a
higher percentage DRE, for example, 99.9999 percent DRE for POHCs for
all hazardous wastes. A higher DRE could be achieved by improving the
design, operation, or maintenance of the combustion system to achieve
greater combustion efficiency.
Sources will not incur costs to achieve the 99.99% DRE floor
because it is an existing RCRA standard . A substantial number of
existing hazardous waste combustors are not likely to be routinely
achieving 99.999% DRE, however, and most are not likely to be achieving
99.9999% DRE. Improvements in combustion efficiency will be required to
meet these beyond-the-floor DREs. Improved combustion efficiency is
accomplished through better mixing, higher temperatures, and longer
residence times. As a practical matter, most combustors are mixing-
limited. Thus, improved mixing is necessary for improved DREs. For a
less-than-optimum burner, a certain amount of improvement may typically
be accomplished by minor, relatively inexpensive combustor
modifications--burner tuning operations such as a change in burner
angle or an adjustment of swirl--to enhance mixing on the macro-scale.
To achieve higher and higher DREs, however, improved mixing on the
micro-scale may be necessary requiring significant, energy intensive
and expensive modifications such as burner redesign and higher
combustion air pressures. In addition, measurement of such DREs may
require increased spiking of POHCs and more sensitive stack sampling
and analysis methods at added expense.
Although we have not quantified the cost-effectiveness of a beyond-
the-floor DRE standard, we do not believe that it would be cost-
effective. For reasons discussed above, we believe that the cost of
achieving each successive order-of-magnitude improvement in DRE will be
at least constant, and more likely increasing. Emissions reductions
diminish substantially, however, with each order of magnitude
improvement in DRE. For example, if a source were to emit 100 gm/hr of
organic hazardous air pollutants assuming zero DRE, it would emit 10
gm/hr at 90 percent DRE, 1 gm/hr at 99 percent DRE, 0.1 gm/hr at 99.9
percent DRE, 0.01 gm/hr at 99.99 percent DRE, and 0.001 gm/hr at 99.999
percent DRE. If the cost to achieve each order of magnitude improvement
in DRE is roughly constant, the cost-effectiveness of DRE decreases
with each order of magnitude improvement in DRE. Consequently, we
conclude that this relationship between compliance cost and diminished
emissions reductions associated with a more stringent DRE standard
suggests that a beyond-the-floor standard is not warranted.
c. What Is the MACT Floor for New Sources? The single best
controlled source, and all other hazardous waste cement kilns, are
subject to the existing RCRA DRE standard under Sec. 266.104(a).
Accordingly, we adopt this standard as the MACT floor for new sources.
d. What Are Our Beyond-the-Floor Considerations for New Sources? As
discussed above, although we have not quantified the cost-effectiveness
of a more stringent DRE standard, diminishing emissions reductions with
each order of magnitude improvement in DRE suggests that cost-
effectiveness considerations would likely come into play. We conclude
that a beyond-the-floor standard is not warranted.
VIII. What Are the Standards for Existing and New Hazardous Waste
Burning Lightweight Aggregate Kilns?
A. To Which Lightweight Aggregate Kilns Do Today's Standards Apply?
The standards promulgated today apply to each existing,
reconstructed, and newly constructed lightweight aggregate plant where
hazardous waste is burned in the kiln. These standards apply to major
source and area source lightweight aggregate facilities. Lightweight
aggregate kilns that do not engage in hazardous waste burning
operations are not subject to this NESHAP; however, these kilns will be
subject to future MACT standards for the Clay Products source category.
B. What Are the Standards for New and Existing Hazardous Waste Burning
Lightweight Aggregate Kilns?
1. What Are the Standards for Lightweight Aggregate Kilns?
In this section, the basis for the emissions standards for
hazardous waste burning lightweight aggregate kilns is discussed. The
kiln emission limits apply to the kiln stack gases from lightweight
aggregate plants that burn hazardous waste. The emissions standards are
summarized below:
[[Page 52891]]
Standards for Existing and New Lightweight Aggregate Kilns
------------------------------------------------------------------------
Hazardous air pollutant or Emissions standard \1\
hazardous air pollutant -------------------------------------------
surrogate Existing sources New sources
------------------------------------------------------------------------
Dioxin/furan................ 0.20 ng TEQ/dscm; or 0.20 ng TEQ/dscm; or
0.40 ng TEQ/dscm 0.40 ng TEQ/dscm
and rapid quench of and rapid quench of
the flue gas at the the flue gas at the
exit of the kiln to exit of the kiln to
less than 400 deg.F. less than 400
deg.F.
Mercury..................... 47 g/dscm.. 43 g/dscm.
Particulate matter.......... 57 mg/dscm (0.025 gr/ 57 mg/dscm (0.025 gr/
dscf). dscf).
Semivolatile metals \2\..... 250 g/dscm. 43 g/dscm.
Low volatile metals \3\..... 110 g/dscm. 110 g/dscm.
Hydrochloric acid/chlorine 230 ppmv............ 41 ppmv.
gas.
Hydrocarbons 2,3............ 20 ppmv (or 100 ppmv 20 ppmv (or 100 ppmv
carbon monoxide). carbon monoxide).
Destruction and removal For existing and new sources, 99.99% for
efficiency. each principal organic hazardous
constituent (POHC) designated. For
sources burning hazardous wastes F020,
F021, F022, F023, F026, or F027, 99.9999%
for each POHC designated.
------------------------------------------------------------------------
\1\ All emission levels are corrected to 7% O2 , dry basis.
\2\ Hourly rolling average. Hydrocarbons are reported as propane.
\3\ Lightweight aggregate kilns that elect to continuously comply with
the carbon monoxide standard must demonstrate compliance with the
hydrocarbon standard of 20 ppmv during the comprehensive performance
test.
2. What Are the Dioxin and Furan Standards?
In today's rule, we establish a standard for new and existing
lightweight aggregate kilns that limits dioxin/furan emissions to
either 0.20 ng TEQ/dscm; or 0.40 ng TEQ/dscm and rapid quench of the
flue gas at the exit of the kiln to less than 400 deg.F. Our rationale
for adopting these standards is discussed below.
a. What Is the MACT Floor for Existing Sources? In the April 1996
proposal, we had dioxin/furan emissions data from only one lightweight
aggregate kiln and pooled that data with the dioxin/furan data for
hazardous waste burning cement kilns to identify the MACT floor
emission level. We stated that it is appropriate to combine the two
data sets because they are adequately representative of general dioxin/
furan behavior and control in either type of kiln. Consequently, floor
control and the floor emission level for lightweight aggregate kilns
were the same as for cement kilns. We proposed a floor emission level
of 0.20 ng TEQ/dscm, or temperature at the inlet to the fabric filter
not to exceed 418 deg.F. (61 FR at 17403.)
Several commenters opposed our proposed approach of pooling the
lightweight aggregate kiln data with the cement kiln dioxin/furan data
for the MACT floor analysis. In order to respond to commenter concerns,
we obtained additional dioxin/furan emissions data from lightweight
aggregate kiln sources. In a MACT reevaluation discussed in the May
1997 NODA, we presented an alternative data analysis method to identify
floor control and the floor emission level. In that NODA, dioxin/furan
floor control was defined as temperature control not to exceed
400 deg.F at the inlet to the fabric filter. That analysis resulted in
a floor emission level of 0.20 ng TEQ/dscm, or 4.1 ng TEQ/dscm and
temperature at the inlet to the fabric filter not to exceed 400 deg.F.
(62 FR at 24231.) An emission level of 4.1 ng TEQ/dscm represents the
highest single run from the test condition with the highest run
average. We concluded that 4.1 ng TEQ/dscm was a reasonable floor
level, from an engineering perspective, given our limited dioxin/furan
data base for lightweight aggregate kilns. (We noted that if this were
a large data set, we would have identified the floor emission level
simply as the highest test condition average.) Due to variability among
the runs of the test condition with the highest condition average and
because a floor level of 4.1 ng TEQ/dscm is 40 percent higher than the
highest test condition average of 2.9 ng TEQ/dscm lightweight aggregate
kilns using floor control will be able to meet routinely a floor
emission level of 4.1 ng TEQ/dscm.
We maintain that the floor methodology discussed in the May 1997
NODA is appropriate and we adopt this approach in today's rule. In that
NODA we identified two technologies for control of dioxin/furan
emissions from lightweight aggregate kilns. The first technology
controls dioxin/furans by quenching kiln gas temperatures at the exit
of the kiln so that gas temperatures at the inlet to the particulate
matter control device are below the temperature range of optimum
dioxin/furan formation. The other technology is activated carbon
injected into the kiln exhaust gas. Because activated carbon injection
is not currently used by any hazardous waste burning lightweight
aggregate kilns, this technology was evaluated only as part of a
beyond-the-floor analysis.
One commenter opposes our approach specifying a MACT floor control
temperature limitation of 400 deg.F at the particulate matter control
device. Instead, the commenter supports a temperature limitation of
417 deg.F, which is the highest temperature associated with any dioxin/
furan test condition in our data base. Although only two of the three
test conditions for which we have dioxin/furan emissions data operated
the fabric filter at 400 deg.F or lower (the third operated at
417 deg.F), we do have other fabric filter operating temperatures from
kilns performing RCRA compliance testing for other hazardous air
pollutants that document fabric filter operations at 400 deg.F or
lower. From these data, we conclude that lightweight aggregate kilns
can operate the fabric filter at temperatures of 400 deg.F or lower.
Thus, identifying floor control at a temperature limitation of
400 deg.F ensures that all lightweight aggregate kilns will be
operating consistent with sound operational practices for controlling
dioxin/furan emissions.
As discussed in the May 1997 NODA, specifying a temperature
limitation of 400 deg.F or lower is appropriate for floor control
because, from an engineering perspective, it is within the range of
reasonable values that could have been selected considering that: (1)
The optimum temperature window for surface-catalyzed dioxin/furan
formation is approximately 450-750 deg.F; and (2) temperature levels
below 350 deg.F can cause dew point condensation problems resulting in
particulate matter control device corrosion. Further, lightweight
aggregate kilns can operate at air pollution control device
temperatures between 350 to 400 deg.F. In
[[Page 52892]]
fact, all lightweight aggregate kilns use (or have available) fabric
filter ``tempering'' air dilution and water quench for cooling kiln
exit gases prior to the fabric filter (some kilns also augment this
with uninsulated duct radiation cooling). Thus, the capability of
operating fabric filters at temperatures lower than 400 deg.F currently
exists and is practical. See the technical support document for further
discussion.165
---------------------------------------------------------------------------
\165\ USEPA, ``Final Technical Support document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999.
---------------------------------------------------------------------------
In summary, today's floor emission level for dioxin/furan emissions
for existing lightweight kilns is 0.20 ng TEQ/dscm or 4.1 ng TEQ/dscm
and control of temperature at the inlet to the fabric filter not to
exceed 400 deg.F. We estimate that all lightweight aggregate kiln
sources currently are meeting the floor level.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? We considered in the April 1996 proposal a beyond-the-floor
standard of 0.20 ng TEQ/dscm based on injection of activated carbon at
a flue gas temperature of less than 400 deg.F. (61 FR at 17403.) In the
May 1997 NODA, we considered a beyond-the-floor standard of 0.20 ng
TEQ/dscm standard based on rapidly quenching combustion gases at the
exit of the kiln to 400 deg.F, and insulating the duct-work between the
kiln exit and the fabric filter to maintain gas temperatures high
enough to avoid dew point problems. (62 FR at 24232.)
One commenter, however, disagrees that there is adequate evidence
(test data) supporting rapid quench of kiln exit gases to less than
400 deg.F can achieve a level of 0.20 ng TEQ/dscm. Based on these NODA
comments and upon closer analysis of all available data, we find that a
level of 0.20 ng TEQ/dscm has not been clearly demonstrated for
lightweight aggregate kilns with rapid quench less than 400 deg.F prior
to the particulate matter control device. The data show that some
lightweight aggregate kilns can achieve a level of 0.20 TEQ ng/dscm
with rapid quench. In addition, one commenter, who operates two
lightweight aggregate kilns with heat exchangers that cool the flue gas
to a temperature of approximately 400 deg.F at the fabric filter,
stated that they achieve dioxin/furan emissions slightly below 0.20 ng
TEQ/dscm. However, because of the small dioxin/furan data base we are
concerned that these limited data may not show the full range of
emissions. Due to the similarity of dioxin/furan control among cement
kilns and lightweight aggregate kilns, we looked to the cement kiln
data to complement our limited lightweight aggregate kiln dataset. As
discussed earlier, cement kilns are able to control dioxin/furans to
0.40 ng TEQ/dscm with temperature control. Since we do not expect a
lightweight aggregate kiln to achieve lower dioxin/furan emissions than
a cement kiln with rapid quench, we agree with these commenters and
conclude that lightweight aggregate kilns can control dioxin/furans to
0.40 ng TEQ/dscm with rapid quench of kiln exit gases to less than
400 deg.F.
Thus, for the final rule, we considered two beyond-the-floor
levels: (1) Either 0.20 ng TEQ/dscm; or 0.40 ng TEQ/dscm and rapid
quench of the kiln exhaust gas to a temperature less than 400 deg.F;
and (2) a level of 0.20 ng TEQ/dscm based on activated carbon
injection.
The first option is a beyond-the-floor standard of either 0.20 ng
TEQ/dscm, or 0.40 ng TEQ/dscm and rapid quench of the kiln exhaust gas
to less than 400 deg.F. The national incremental annualized compliance
cost for lightweight aggregate kilns to meet this beyond-the-floor
level rather than comply with the floor controls would be approximately
$50,000 for the entire hazardous waste burning lightweight aggregate
kiln industry, and would provide an incremental reduction in dioxin/
furan emissions beyond the MACT floor controls of nearly 2 g TEQ/yr.
Based on these costs of approximately $25 thousand per additional g
of dioxin/furan removed and on the significant reduction in dioxin/
furan emissions achieved, we have determined that this dioxin/furan
beyond-the-floor option for lightweight aggregate kilns is justified,
especially given our special concern about dioxin/furans. Dioxin/furans
are some of the most toxic compounds known due to their bioaccumulation
potential and wide range of health effects, including carcinogenesis,
at exceedingly low doses. Exposure via indirect pathways is a chief
reason that Congress singled out dioxin/furans for priority MACT
control in section 112(c)(6) of the CAA. See S. Rep. No. 128, 101st
Cong. 1st Sess. at 154-155.
We also evaluated, but rejected, activated carbon injection as a
beyond-the-floor option. Carbon injection is routinely effective at
removing 99 percent of dioxin/furans at numerous municipal waste
combustor and medical waste combustor applications and one hazardous
waste incinerator application. However, no hazardous waste burning
lightweight aggregate kiln currently uses activated carbon injection
for dioxin/furan removal. We believe that it is conservative to assume
that only 95 percent is achievable given potential uncertainties in its
application to lightweight aggregate kilns. In addition, we assumed for
cost-effectiveness calculations that lightweight aggregate kilns
needing activated carbon injection would install the activated carbon
injection system after the existing fabric filter device and add a new
smaller fabric filter to remove the injected carbon with the absorbed
dioxin/furans and mercury. This costing approach addresses commenter's
concerns that injected carbon may interfere with current dust recycling
practices.
The national incremental annualized compliance cost for lightweight
aggregate kilns to meet a beyond-the-floor level based on activated
carbon injection rather than comply with the floor controls would be
approximately $1.2 million for the entire hazardous waste burning
lightweight aggregate kiln industry. This would provide an incremental
reduction in dioxin/furan emissions beyond the MACT floor controls of
2.2 g TEQ/yr, or 90 percent. Based on these costs of approximately
$0.53 million per additional g of dioxin/furan removed and the small
incremental dioxin/furan emissions reduction beyond the dioxin/furan
beyond-the-floor option discussed above (2.0 g TEQ/yr versus 2.2 g TEQ/
yr), we have determined that this second beyond-the-floor option for
lightweight aggregate kilns is not justified. Therefore, we are not
promulgating a beyond-the-floor standard of 0.20 ng TEQ/dscm for
lightweight aggregate kilns based on activated carbon injection.
Thus, the promulgated dioxin/furan standard for existing
lightweight aggregate kilns is a beyond-the-floor standard of 0.20 ng
TEQ/dscm; or 0.40 ng TEQ/dscm and rapid quench to a temperature not to
exceed 400 deg.F based on rapid quench of flue gas at the exit of the
kiln.
c. What Is the MACT Floor for New Sources? In the April 1996
proposal, the floor analysis for new lightweight aggregate kilns was
the same as for existing kilns, and the proposed standard was the same.
The proposed floor emission level was 0.20 ng TEQ/dscm, or temperature
at the inlet to the particulate matter control device not to exceed
418 deg.F. (61 FR at 17408.) In the May 1997 NODA, we used an
alternative data analysis method to identify floor control and the
floor emission level. As done for existing sources, floor control for
new sources was defined as temperature control at the inlet to the
particulate matter control device to less than 400 deg.F. That
[[Page 52893]]
analysis resulted in a floor emission level of 0.20 ng TEQ/dscm, or 4.1
ng TEQ/dscm and temperature at the inlet to the fabric filter not to
exceed 400 deg.F. Our engineering evaluation indicated that the best
controlled source is one that is controlling temperature control at the
inlet to the fabric filter at 400 deg.F. (62 FR at 24232.) We continue
to believe that the floor methodology discussed in the May 1997 NODA is
appropriate for new sources and we adopt this approach in the final
rule. The floor level for new lightweight aggregate kilns is 0.20 ng
TEQ/dscm, or 4.1 ng TEQ/dscm and temperature at the inlet to the
particulate matter control device not to exceed 400 deg.F.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the April 1996 proposal, we proposed activated carbon injection as
beyond-the-floor control and a beyond-the-floor standard of 0.20 ng
TEQ/dscm. (61 FR at 17408.) In the May 1997 NODA, we identified a
beyond-the-floor standard of 0.20 ng TEQ/dscm based on rapid quench of
kiln gas to less than 400 deg.F combined with duct insulation or
activated carbon injection operated at less than 400 deg.F. (62 FR at
24232.) These beyond-the-floor considerations are identical to those
discussed above for existing sources.
The beyond-the-floor standard identified for existing sources
continues to be appropriate for new sources for the same reasons. Thus,
the promulgated dioxin/furan standard for new lightweight aggregate
kilns is the same as the standard for existing standards, i.e., 0.20 ng
TEQ/dscm or 0.40 ng TEQ/dscm and rapid quench of the kiln exhaust gas
to less than 400 deg.F.
3. What Are the Mercury Standards?
In the final rule, we establish a standard for existing and new
lightweight aggregate kilns that limits mercury emissions to 47 and 33
g/dscm, respectively. The rationale for adopting these
standards is discussed below.
a. What Is the MACT Floor for Existing Sources? All lightweight
aggregate kilns use fabric filters, and one source uses a venturi
scrubber in addition to a fabric filter. However, since mercury is
generally in the vapor form in and downstream of the combustion
chamber, including in the air pollution control device, fabric filters
alone do not achieve significant mercury control. Mercury emissions
from lightweight aggregate kilns are currently controlled under
existing regulations through limits on the maximum feedrate of mercury
in total feedstreams (e.g., hazardous waste, raw materials). Thus, MACT
floor control is based on limiting the feedrate of mercury in hazardous
waste.
In the April 1996 proposal, we identified floor control as
hazardous waste feedrate control not to exceed a feedrate level of 17
g/dscm, expressed as a maximum theoretical emissions
concentration, and proposed a floor emission level of 72 g/
dscm based on an analysis of data from all lightweight aggregate kilns
with a hazardous waste feedrate of mercury of this level or lower. (61
FR at 17404.) In the May 1997 NODA, we conducted a breakpoint analysis
on ranked mercury emissions data and established the floor emission
level equal to the test condition average of the breakpoint source. (62
FR at 24232.) The breakpoint analysis was intended to reflect an
engineering-based evaluation of the data whereby the few lightweight
aggregate kilns spiking extra mercury during testing procedures did not
drive the floor emission level to levels higher than the preponderance
of the emission data. We reasoned that sources with emissions higher
than the breakpoint source were not controlling the hazardous waste
feedrate of mercury to levels representative of MACT. The May 1997 NODA
analysis resulted in a MACT floor level of 47 g/dscm.
One commenter states that the use of mercury stack gas measurements
from RCRA compliance test reports is inappropriate for setting the MACT
floor since they are based on feeding normal wastes. With the exception
of one source, no mercury spiking was done during the RCRA compliance
testing because lightweight aggregate kilns complied with Tier I levels
allowable in the Boiler and Industrial Furnace rule. The commenter
notes that the Tier I allowable levels are above, by orders of
magnitude, the total mercury fed into lightweight aggregate kilns.
Thus, to set the mercury MACT floor, the commenter states that we need
to consider the potential range of mercury levels in the hazardous
waste and raw materials, which may not represented by the RCRA
compliance stack gas measurements.
We recognize that stack gas tests generating mercury emissions data
were conducted with normal unspiked waste streams containing normal
levels of mercury in hazardous waste. However, we concluded that it is
appropriate in this particular circumstance to use unspiked data to
define a MACT floor. See discussion in Part Four, Section V.D.1. It
would hardly reflect MACT to base the floor emission level on a
feedrate of mercury greater than that which actually occurs in
hazardous waste fuels burned in these units. Furthermore, the final
rule standard is projected to be achievable by lightweight aggregate
kilns for the vast majority of the wastes they are currently handling.
The standard would allow lightweight aggregate kilns to burn wastes
with about 0.5 ppmw mercury, without use of add-on mercury control
techniques such as carbon injection. Data provided by a commenter
indicates that approximately 90% of the waste streams lightweight
aggregate kilns currently burn do not contain mercury levels at 2 ppmw.
Further, the commenter indicates that these wastes are typically less
than 0.02 ppmw mercury when more refined and costly analysis techniques
are used. Thus, the standard is consistent with the current practice of
lightweight aggregate kilns burning low-mercury waste.
We received comments from the lightweight aggregate kiln industry
expressing concern with the stringency of the mercury standard. These
commenters oppose a mercury standard of 47 g/dscm, in part,
because of the difficulty and increased cost of demonstrating
compliance with day-to-day mercury feedrate limits. One potential
problem pertains to raw material mercury detection limits. The
commenter states that mercury is generally not measured in the raw
material at detectable levels at their facilities. The commenter points
out that if a kiln assumes mercury is present in the raw material at
the detection limit, the resulting calculated uncontrolled mercury
emission concentration could exceed, or be a significant percentage of,
the mercury emission standard. This may prevent a kiln from complying
with the mercury emission standard even though MACT control is used.
Further, the commenter anticipates that more frequent analysis,
additional laboratory equipment and staff, and improved testing and
analysis procedures will be required to show compliance with a standard
of 47 g/dscm. The commenter states that the costs of
compliance will increase significantly at each facility to address this
nondetect issue.
Four provisions in the final rule offer flexibility in complying
with the mercury standard. For example, one provision allows sources to
petition for an alternative mercury standard that only requires
compliance with a hazardous waste mercury feedrate limitation, provided
that mercury not been present historically in the raw material at
detectable levels. This approach ensures that kilns using MACT controls
can achieve the mercury standard. The details of this provision are
discussed in Part Five, Section
[[Page 52894]]
X.A.2. Another provision allows kilns a waiver of performance testing
requirements when the source feeds low levels of mercury. Under this
provision, a kiln qualifies for a waiver of the performance testing
requirements for mercury if all mercury from all feedstreams fed to the
combustion unit does not exceed the mercury emission standard. For
kilns using this waiver, we allow kilns to assume mercury in the raw
material is present at one-half the detection limit whenever the raw
materials feedstream analysis determines that mercury is not present at
detectable levels. The details of this provision are presented in Part
Five, Section X.B. For a discussion of the other two methods that can
be used to comply with the mercury emission standard, see Part Five,
Section VII.B.6.
For today's rule we use a revised engineering evaluation and data
analysis method to establish the MACT floor emission level for mercury.
The approach used to establish MACT floors for the three metal
hazardous air pollutant groups and hydrochloric acid/chlorine gas is
the aggregate feedrate approach. Using this approach, the resulting
mercury floor emission level is 47 g/dscm.
We estimate that approximately 75 percent of lightweight aggregate
kiln sources currently are meeting the floor emission level. The
national annualized compliance cost for lightweight aggregate kilns to
reduce mercury emissions to comply with the floor emission level is
$0.7 million for the entire hazardous waste burning lightweight
aggregate kiln industry, and will reduce mercury emissions by
approximately 0.03 Mg/yr or 47 percent from current baseline emissions.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the April 1996 NPRM, we considered a beyond-the-floor
standard based on flue gas temperature reduction to 400 deg.F or less
followed by activated carbon injection, but determined that a beyond-
the-floor level would not be cost-effective and therefore warranted.
(61 FR at 17404.) In the May 1997 NODA, we considered a beyond-the-
floor standard of 15 g/dscm based on an activated carbon
injection. However, we indicated in the NODA that a beyond-the-floor
standard would not likely be justified given the high cost of treatment
and the relatively small amount of mercury removed from air emissions.
(62 FR at 24232.)
In developing the final rule, we identified three techniques for
control of mercury as a basis to evaluate a beyond-the-floor standard:
(1) Activated carbon injection; (2) limiting the feed of mercury in the
hazardous waste; and (3) limiting the feed of mercury in the raw
materials. The results of each analysis are discussed below.
Activated Carbon Injection. To investigate this beyond-the-floor
control option, we applied a carbon injection capture efficiency of 80
percent to the floor emission level of 47 g/dscm. The
resulting beyond-the-floor emission level is 10 g/dscm.
The national incremental annualized compliance cost for lightweight
aggregate kilns to meet this beyond-the-floor level rather than comply
with the floor controls would be approximately $0.6 million for the
entire hazardous waste burning lightweight aggregate kiln industry and
would provide an incremental reduction in mercury emissions beyond the
MACT floor controls of 0.02 Mg/yr. Based on these costs of
approximately $34 million per additional Mg of mercury removed and the
small emissions reductions that would be realized, we conclude that
this mercury beyond-the-floor option for hazardous waste burning
lightweight aggregate kilns is not acceptably cost-effective nor
otherwise justified. Therefore, we do not adopt this beyond-the-floor
standard.
Limiting the Feedrate of Mercury in Hazardous Waste. We also
considered, but rejected, a beyond-the-floor emission level based on
limiting the feed of mercury in the hazardous waste. This mercury
beyond-the-floor option for lightweight aggregate kilns is not
warranted because data submitted by commenters indicate that
approximately 90% of the hazardous waste burned by lightweight
aggregate kilns contains mercury at levels below method detection
limits. We conclude from these data that there are little additional
mercury reductions possible by reducing the feed of mercury in the
hazardous waste. Therefore, we are not adopting a beyond-the-floor
emission level because it will not be cost-effective due to the
relatively small amount of mercury removed from air emissions and
likely problems with method detection limitations.
Limiting the Feedrate of Mercury in Raw Materials. A source can
achieve a reduction in mercury emissions by substituting a feed
material containing lower levels of mercury for a primary raw material
higher mercury levels. This beyond-the-floor option appears to be less
cost effective compared to either of the options evaluated above.
Because lightweight aggregate kilns are sited proximate to primary raw
material supply and transporting large quantities of an alternative
source of raw material(s) is expected to be cost prohibitive.
Therefore, we do not adopt this mercury beyond-the-floor standard.
Thus, the promulgated mercury standard for existing hazardous waste
burning lightweight aggregate kilns is the floor emission level of 47
g/dscm.
c. What Is the MACT Floor for New Sources? In the April 1996
proposal, we identified floor control for new sources as hazardous
waste feedrate control of mercury not to exceed a feedrate level of 17
g/dscm expressed as a maximum theoretical emissions
concentration. We proposed a floor emission level of 72 g/
dscm. (61 FR at 17408.) In May 1997 NODA, we conducted a breakpoint
analysis on ranked mercury emissions data from sources utilizing the
MACT floor technology and established the floor emission level as the
test condition average of the breakpoint source. The breakpoint
analysis was intended to reflect an engineering-based evaluation of the
data so that the one lightweight aggregate kiln spiking extra mercury
during testing procedures did not drive the floor emission level to
levels higher than the preponderance of the emissions data. This
analysis resulted in a MACT floor level of 47 g/dscm. (62 FR
at 24233.)
For the final rule, we identify floor control for new lightweight
aggregate kilns as feed control of mercury in the hazardous waste,
based on the single source with the best aggregate feedrate of mercury
in hazardous waste. Using the aggregate feedrate approach to establish
this floor level of control and corresponding floor emission level, we
identify a MACT floor emission level of 33 g/dscm for new
lightweight aggregate kilns.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
both the proposal and the NODA, we considered a beyond-the-floor
standard for new sources based on activated carbon injection, but
determined that it would not be cost-effective to adopt the beyond-the-
floor standard given the high cost of treatment and the relatively
small amount of mercury removed from air emissions. (61 FR at 17408 and
62 FR at 24233.)
In the final rule, we identified three techniques for control of
mercury as a basis to evaluate a beyond-the-floor standard: (1)
Activated carbon injection; and (2) limiting the feed of mercury in the
hazardous waste. The results of each analysis are discussed below.
Activated Carbon Injection. As discussed above, we conclude that
flue gas temperature reduction to 400 deg.F followed by activated
carbon injection to remove mercury is an appropriate beyond-the-floor
control option for improved mercury control at
[[Page 52895]]
lightweight aggregate kilns. The control of flue gas temperature is
necessary to ensure good collection efficiency. Based on the MACT floor
emission level of 33 g/dscm and assuming a carbon injection
capture efficiency of 80 percent, we identified a beyond-the-floor
emission level of 7 g/dscm. As discussed above for existing
sources, we do not believe that a beyond-the-floor standard of 7
g/dscm is warranted for new lightweight aggregate kilns due to
the high cost of treatment and relatively small amount of mercury
removed from air emissions. The incremental annualized compliance cost
for one new lightweight aggregate kiln to meet this beyond-the-floor
level, rather than comply with floor controls, would be approximately
$0.46 million and would provide an incremental reduction in mercury
emissions beyond the MACT floor controls of approximately 0.008 Mg/yr.
Based on these costs of approximately $58 million per additional Mg of
mercury removed, a beyond-the-floor standard of 7 g/dscm is
not warranted due to the high cost of compliance and relatively small
mercury emissions reductions. Notwithstanding our goal of reducing the
loading to the environment by bioaccumulative pollutants such as
mercury whenever possible, these costs are not justified.
Limiting the Feedrate of Mercury in Hazardous Waste. As discussed
above for existing sources, we conclude that a beyond-the-floor based
on limiting the feed of mercury in the hazardous waste is not
justified. Considering that the floor emission level for new
lightweight aggregate kilns is approximately one third lower than the
floor emission level for existing kilns (33 versus 47 g/dscm),
we again conclude that a mercury beyond-the-floor standard is not
warranted because emission reductions of mercury would be less than
existing sources at comparable costs. Thus, the cost-effectiveness is
higher for new kilns than for existing kilns. Further, achieving
substantial additional mercury reductions by further controls on
hazardous waste feedrate may be problematic because the mercury
contribution from raw materials and coal represents an even larger
proportion of the total mercury fed to the kiln. Therefore, we do not
adopt a mercury beyond-the-floor standard based on limiting feed of
mercury in hazardous waste for new sources.
Thus, the promulgated mercury standard for new hazardous waste
burning lightweight aggregate kilns is the floor emission level of 33
g/dscm.
4. What Are the Particulate Matter Standards?
We establish standards for both existing and new lightweight
aggregate kilns that limit particulate matter emissions to 57 mg/dscm.
The particulate matter standard is a surrogate control for the metals
antimony, cobalt, manganese, nickel, and selenium. We refer to these
five metals as ``nonenumerated metals'' because standards specific to
each metal have not been established. The rationale for adopting these
standards is discussed below.
a. What Is the MACT Floor for Existing Sources? In the April 1996
NPRM, we defined floor control based upon the performance of a fabric
filter with an air-to-cloth ratio of 2.8 acfm/ft2. The MACT
floor was 110 mg/dscm (0.049 gr/dscf). (61 FR at 17403.) In the May
1997 NODA, we defined the technology basis as a fabric filter for a
MACT floor, but did not characterize the design and operation
characteristics of the particulate matter control equipment, air-to-
cloth ratio of a fabric filter, because we had limited information on
these parameters. (62 FR at 24233.) Instead, for each particulate
matter test condition, we evaluated the corresponding semivolatile
metal system removal efficiency and screened out sources with
relatively poor system removal efficiencies as a means to identify and
eliminate from consideration those sources not using MACT floor
control. Our reevaluation of the lightweight aggregate kiln particulate
matter data resulted in a MACT floor of 50 mg/dscm (0.022 gr/dscf).
Some commenters state that a floor emission level of 50 mg/dscm
(0.022 gr/dscf) is too high and a particulate matter standard of 23 mg/
dscm (0.010 gr/dscf) is more appropriate because it is consistent with
the level of performance achieved by incinerators using fabric filters.
Even though we agree that well designed and properly operated fabric
filters in use at all lightweight aggregate kilns can achieve low
levels, we are concerned that an emission level of 23 mg/dscm would not
be appropriate given the high inlet grain loading inherent with the
lightweight aggregate manufacturing process, typically much higher than
the particulate loading to incinerators.
Commenters also express concern that the Agency identified
separate, different MACT pools and associated MACT controls for
particulate matter, semivolatile metals, and low volatile metals, even
though all three are controlled, at least in part, by the particulate
matter control device. These commenters stated that our approach is
likely to result in three different design specifications. We agree
with these commenters and, in the final rule, the same initial MACT
pool is used to establish the floor levels for particulate matter,
semivolatile metals, and low volatile metals. See discussion in Part
Four, Section V.
For the final rule, we conclude that the general floor methodology
discussed in the May 1997 NODA is appropriate. MACT control for
particulate matter is based on the performance of fabric filters. Since
we lack data to fully characterize control equipment from all sources
and we lack information on the relationship between the design
parameters and the system performance, we evaluated both low and
semivolatile metal system removal efficiencies associated with the
source's particulate matter emissions to identify those sources not
using MACT floor control. Our data show that all lightweight aggregate
kilns are achieving greater than 99 percent system removal efficiency
for both low and semivolatile metals, with some attaining 99.99 percent
removal. Since we found no sources with system removal efficiencies
indicative of poor performance, we conclude that all lightweight
aggregate kilns are using MACT controls and the floor emission limit is
identified as 57 mg/dscm (0.025 gr/dscf).
The performance level of 57 mg/dscm is generally consistent with
that expected from well designed and operated fabric filters, and that
achieved by other similar types of combustion sources operating with
high inlet grain loadings. We have particulate matter data from all
lightweight aggregate kiln sources, and multiple test conditions,
conducted at 3 year intervals, are available for many of the sources.
We conclude that the number of test conditions available adequately
covers the range of variability of well operated and designed fabric
filters.166
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\166\ USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999.
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We considered, but rejected, basing the particulate matter floor
for lightweight aggregate kilns on the New Source Performance Standard.
The New Source Performance Standard limits particulate matter emissions
to 92 mg/dscm (0.040 gr/dscf), uncorrected for oxygen. (See 40 CFR
60.730, Standards of Performance for Calciners and Dryers in Mineral
Industries.) We rejected the New Source Performance Standard as the
basis for the floor emission level
[[Page 52896]]
because our MACT analysis of data from existing sources indicates that
a particulate matter floor level lower than the New Source Performance
Standard is currently being achieved by existing hazardous waste
burning lightweight aggregate kilns. Further, all available emission
data for hazardous waste burning lightweight aggregate kilns are well
below the New Source Performance Standard particulate matter standard.
Thus, the particulate matter floor emission level is 57 mg/dscm based
on an analysis of existing emissions data.
We estimate that, based on a design level of 70 percent of the
standard, over 90 percent of lightweight aggregate kiln sources
currently are meeting the floor level. The national annualized
compliance cost for lightweight aggregate kilns to reduce particulate
matter emissions to comply with the floor emission level is $18,000 for
the entire hazardous waste burning lightweight aggregate kiln industry,
and our floor will reduce nonenumerated metals and particulate matter
emissions by 0.01 Mg/yr and 2.7 Mg/yr, respectively, or 7 percent from
current baseline emissions.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the NPRM, we proposed a beyond-the-floor emission level of
69 mg/dscm (0.030 gr/dscf) and solicited comment on an alternative
beyond-the-floor emission level of 34 mg/dscm (0.015 gr/dscf) based on
improved particulate matter control. (61 FR at 17403.) In the May 1997
NODA, we concluded that a beyond-the-floor standard may not be
warranted given a reduced particulate matter floor level compared to
the proposed floor emission level. (62 FR at 24233.)
In the final rule, we considered a beyond-the-floor level of 34 mg/
dscm for existing lightweight aggregate kilns based on improved
particulate matter control. For analysis purposes, improved particulate
matter control entails the use of higher quality fabric filter bag
material. We then determined the cost of achieving this level of
particulate matter, with corresponding reductions in the nonenumerated
metals for which particulate matter is a surrogate, to determine if
this beyond-the-floor level would be appropriate. The national
incremental annualized compliance cost for lightweight aggregate kilns
to meet this beyond-the-floor level, rather than comply with the floor
controls, would be approximately $110,000 for the entire hazardous
waste burning lightweight aggregate kiln industry and would provide an
incremental reduction in nonenumerated metals emissions nationally
beyond the MACT floor controls of 0.03 Mg/yr. Based on these costs of
approximately $3.7 million per additional Mg of nonenumerated metals
emissions removed, we conclude that this beyond-the-floor option for
lightweight aggregate kilns is not acceptably cost-effective nor
otherwise justified. Therefore, we do not adopt this beyond-the-floor
standard. Thus, the promulgated particulate matter standard for
existing hazardous waste burning lightweight aggregate kilns is the
floor emission level of 57 mg/dscm.
c. What Is the MACT Floor for New Sources? In the April 1996
proposal, we defined floor control for new sources based on the level
of performance of a fabric filter with an air-to-cloth ratio of 1.5
acfm/ft2. The MACT floor emission level was 120 mg/dscm (0.054 gr/
dscf). (61 FR at 17408.) In the May 1997 NODA, MACT control was defined
as a well-designed and properly operated fabric filter, and the floor
emission level for new lightweight aggregate kilns was 50 mg/dscm
(0.022 gr/dscf). (62 FR at 24233.)
All lightweight aggregate kilns use fabric filters to control
particulate matter. As discussed earlier, we have limited information
on the design and operation characteristics of existing control
equipment currently used by lightweight aggregate kilns. As a result,
we are unable to identify a specific technology that can consistently
achieve lower emission levels than the controls used by lightweight
aggregate kilns achieving the MACT floor level for existing sources.
Lightweight aggregate kilns achieve the floor emission level with well-
designed and properly operated fabric filters. Thus, floor control for
new kilns is likewise a well-designed and properly operated fabric
filter. Therefore, as discussed for existing sources, the MACT floor
level for new lightweight aggregate kilns is 57 mg/dscm (0.025 gr/
dscf).
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the April 1996 NPRM, we proposed a beyond-the-floor standard of 69 mg/
dscm (0.030 gr/dscf) based on improved particulate matter control,
which was consistent with existing sources. (61 FR at 17408.) In the
May 1997 NODA, we concluded, as we did for existing sources, that a
beyond-the-floor level for particulate matter may not be warranted due
to the high costs of control and relatively small amount of particulate
matter removed from air emissions. (62 FR at 24233.)
As discussed for existing sources, we considered a beyond-the-floor
level of 34 mg/dscm for new lightweight aggregate kilns based on
improved particulate matter control. For analysis purposes, improved
particulate matter control entails the use of higher quality fabric
filter bag material. We then determined the cost of achieving this
level of particulate matter, with corresponding reductions in the
nonenumerated metals for which particulate matter is a surrogate, to
determine if this beyond-the-floor level would be appropriate. The
incremental annualized compliance cost for one new lightweight
aggregate kiln to meet this beyond-the-floor level, rather than comply
with floor controls, would be approximately $38 thousand and would
provide an incremental reduction in nonenumerated metals emissions of
approximately 0.012 Mg/yr.167 Based on these costs of
approximately $3.1 million per additional Mg of nonenumerated metals
removed, we conclude that a beyond-the-floor standard of 34 mg/dscm is
not justified due to the high cost of compliance and relatively small
nonenumerated metals emission reductions. Further, a standard of 57 mg/
dscm would adequately control the unregulated hazardous air pollutant
metals for which it is being used as a surrogate. Thus, the particulate
matter standard for new lightweight aggregate kilns is the floor level
of 57 mg/dscm.
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\167\ Based on the data available, the average emissions in sum
of the five nonenumerated metal from lightweight aggregate kilns
using MACT particulate matter control is approximately 83
g/dscm. To estimate emission reductions of the
nonenumerated metals, we assume a linear relationship between a
reduction in particulate matter and these metals.
---------------------------------------------------------------------------
5. What Are the Semivolatile Metals Standards?
In the final rule, we establish a standard for existing and new
lightweight aggregate kilns that limits semivolatile metal emissions to
250 and 43 g/dscm, respectively. The rationale for adopting
these standards is discussed below.
a. What Is the MACT Floor for Existing Sources? All lightweight
aggregate kilns use a combination of particulate matter control, i.e.,
a fabric filter, and hazardous waste feedrate to control emissions of
semivolatile metals. Current RCRA regulations establish limits on the
maximum feedrate of lead and cadmium in all feedstreams. Thus,
hazardous waste feedrate control is part of MACT floor control.
In the April 1996 proposal, we defined floor control as either (1)
a fabric filter with an air-to-cloth ratio of 1.5 acfm/ft 2
and a hazardous waste feedrate level of 270,000 g/dscm,
[[Page 52897]]
expressed as a maximum theoretical emissions concentration; or (2) a
combination of a fabric filter and venturi scrubber with an air-to-
cloth ratio of 4.2 acfm/ft 2 and a hazardous waste feedrate
level of 54,000 g/dscm. The proposed floor emission level was
12 g/dscm. (61 FR at 17405.) In the May 1997 NODA, we
discussed a floor methodology where we used a breakpoint analysis to
identify sources that were not using floor control with respect either
to semivolatile metals hazardous waste feedrate or emissions control.
Under this approach, we ranked semivolatile metal emissions data from
sources that were achieving the particulate matter floor level of 50
mg/dscm or better. We identified the floor level as the test condition
average associated with the breakpoint source. Thus, sources with
atypically high emissions because of high semivolatile feedrate levels
or poor semivolatile metals control were screened from the pool of
sources used to define the floor emission level. Based on this
analysis, we identified a floor emission level of 76 g/dscm.
(62 FR at 24234.)
We received few public comments in response to the proposal and May
1997 NODA concerning the lightweight aggregate kiln semivolatile metals
floor emission level. We did receive comments on the application of
techniques to identify breakpoints in the arrayed emissions data. This
issue and our response to it are discussed in the floor methodology
section in Part Four, Section V. We also received comments that our
semivolatile metals analysis in the proposal and May 1997 NODA included
several data base inaccuracies that, when corrected, would result in a
higher floor level. We agree with the commenters and we revised the
data base as necessary for the final rule analysis.
In the final rule, in general response to these comments, we use a
revised engineering evaluation and data analysis method to establish
the floor emission level for semivolatile metals. We use the aggregate
feedrate approach in conjunction with floor control for particulate
matter of 57 mg/dscm to identify a semivolatile metal floor emission
level of 1,700 g/dscm. We estimate that all lightweight
aggregate kiln sources currently are meeting the floor level.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the April 1996 NPRM, we considered a beyond-the-floor
emission level for semivolatile metals based on improved particulate
matter control. We concluded that a beyond-the-floor emission level
would not be cost-effective given that the proposed semivolatile metal
floor level of 12 g/dscm alone would result in an estimated 97
percent reduction in semivolatile metal emissions. (61 FR at 17405.) In
the May 1997 NODA, we considered a beyond-the-floor emission level
based on improved particulate matter control, but indicated that such a
standard was not likely to be cost-effective due to the high costs of
control. (62 FR at 24234.)
In developing the final rule, we identified three techniques for
control of semivolatile metals as a basis to evaluate a beyond-the-
floor standard: (1) Limiting the feed of semivolatile metals in the
hazardous waste; (2) improved particulate matter control; and (3)
limiting the feed of semivolatile metals in the raw materials. The
results of each analysis are discussed below.
Limiting the Feedrate of Semivolatile Metals in Hazardous Waste.
Under this option, as with cement kilns, we selected for evaluation a
beyond-the-floor emission level of 240 g/dscm to evaluate from
among the range of possible levels that reflect improved feedrate
control of semivolatile metals in hazardous waste. This emission level
represents a significant increment of emission reduction from the floor
level of 1700 g/dscm, it is within the range of levels that
are likely to be reasonably achievable using feedrate control, and it
is generally consistent with the incinerator and cement kiln standards,
thereby advancing a policy objective of essentially common standards
among combustors of hazardous waste.
In performing an analysis of the 240 g/dscm beyond-the-
floor limit, we found that additional reductions beyond 250 g/
dscm represent a significant reduction in cost-effectiveness of
incremental beyond-the-floor levels. A beyond-the-floor standard of 250
g/dscm achieves the same goals as a beyond-the-floor standard
of 240 g/dscm in a more cost-effective manner. The national
incremental annualized compliance cost for the lightweight aggregate
kilns to meet this 250 g/dscm beyond-the-floor level, rather
than comply with the floor controls, would be approximately $88,000 and
would provide an incremental reduction beyond emissions at the MACT
floor in semivolatile metal emissions of an additional 0.17 Mg/yr. The
cost-effectiveness of this emission level is approximately $530,000 per
additional Mg of semivolatile metal removed.
We conclude that additional control of the feedrate of semivolatile
metals in hazardous waste to achieve an emission level of 250
g/dscm is warranted because this standard would reduce lead
and cadmium emissions, which are particularly toxic hazardous air
pollutants. In addition, Solite Corporation, which operates the
majority of the hazardous waste burning lightweight aggregate kilns,
stated in their public comments that a standard of 213 g/dscm
is achievable and adequately reflects the variability of lead and
cadmium in raw material for their kilns. Further, the vast majority of
the lead and cadmium fed to the lightweight aggregate kiln is from the
hazardous waste,168 not from the raw material or coal. We
are willing to accept a more marginal cost-effectiveness for sources
voluntarily burning hazardous waste in lieu of other fuels to ensure
that sources are using best controls.
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\168\ USEPA, ``Final Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies'', July 1999.
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Moreover, this beyond-the-floor semivolatile metal standard better
supports our Children's Health Initiative in that lead emissions, which
are of highest significance to children's health, will be reduced by
another 60 percent from today's baseline. We are committed to reducing
lead emissions wherever and whenever possible. Finally, we note that
this beyond-the-floor standard is also consistent with European Union
standards for hazardous waste incinerators of approximately 200
g/dscm for lead and cadmium combined. Therefore, we are
adopting today a beyond-the-floor standard of 250 g/dscm for
existing lightweight aggregate kilns.
Improved Particulate Matter Control. We also evaluated improved
particulate matter control as another beyond-the-floor control option
for improved semivolatile metals control. We investigated a beyond-the-
floor standard of 250 g/dscm, an emission level consistent
with the preferred option based on limiting the feedrate of
semivolatile metals in hazardous waste. The national incremental
annualized compliance cost for lightweight aggregate kilns to meet this
beyond-the-floor level, rather than comply with the floor controls,
would be approximately $88,000 thousand for all lightweight aggregate
kilns and would provide an incremental reduction in semivolatile metal
emissions beyond the MACT floor controls of 0.17 Mg/yr. Based on these
costs of approximately $530,000 per additional Mg of semivolatile metal
removed, we determined that this beyond-the-floor option may be
warranted. However, as discussed below, the cost-effectiveness for this
beyond-the-floor option is approximately equivalent to the costs
[[Page 52898]]
estimated for a beyond-the-floor option based on limiting the feed of
semivolatile metals in the hazardous waste. We decided to base the
beyond-the-floor standard for semivolatile metals on the feedrate
option to be consistent with the cement kiln approach. Of course light-
weight aggregate kilns are free to choose to improve particulate matter
control in lieu of feedrate controls as their vehicle to achieve
compliance with 250 ug/dscm.
Limiting the Feedrate of Semivolatile Metals in Raw Materials. A
source can achieve a reduction in semivolatile metals emissions by
substituting a feed material containing lower levels of lead and/or
cadmium for a primary raw material higher in lead and/or cadmium
levels. This beyond-the-floor option appears to be less cost effective
compared to either of the options evaluated above because lightweight
aggregate kilns are sited proximate to primary raw material supply.
Transporting large quantities of an alternative source of raw
material(s) is expected to be cost prohibitive. Therefore, we do not
adopt this semivolatile metal beyond-the-floor standard.
Thus, the promulgated semivolatile metals standard for existing
hazardous waste burning lightweight aggregate kilns is a beyond-the-
floor standard of 250 g/dscm based on limiting the feedrate of
semivolatile metals in the hazardous waste.
c. What Is the MACT Floor for New Sources? In the April 1996
proposal, we defined floor control as a fabric filter with an air-to-
cloth ratio of 1.5 acfm/ft2 and a hazardous waste feedrate
level of 270,000 g/dscm, expressed as a maximum theoretical
emissions concentration. The proposed floor emission level was 5.2
g/dscm. (61 FR at 17408.) In the May 1997 NODA, we concluded
that the floor control and emission level for existing sources for
semivolatile metals would also be appropriate for new sources. Floor
control was based on a combination of good particulate matter control
and limiting hazardous waste feedrates of semivolatile metals to
control emissions. We used a breakpoint analysis of the semivolatile
metal emissions data to exclude sources achieving substantially poorer
semivolatile metal control than the majority of sources. The NODA floor
emission level was 76 g/dscm for new sources. (62 FR at
24234.)
In the final rule, as discussed previously, we use a revised
engineering evaluation and data analysis method to establish the floor
emission level for semivolatile metals. We use the aggregate feedrate
approach in conjunction with floor control for particulate matter of 57
mg/dscm to identify a semivolatile metal floor emission level of 43
g/dscm.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the April 1996 NPRM and May 1997 NODA, we considered a semivolatile
metal beyond-the-floor emission level for new sources, but determined
that the standard would not be cost-effective because the floor
emission levels already achieved significant reductions in semivolatile
metals emissions. (61 FR at 17408 and 62 FR at 24234.)
For the final rule, we do not adopt a beyond-the-floor emission
level because the MACT floor for new sources is already substantially
lower than the beyond-the-floor emission standard for existing sources.
As a result, a beyond-the-floor standard for new lightweight aggregate
kilns is not warranted due to the high costs of control versus the
minimal emissions reductions that would be achieved. Therefore, we
adopt the semivolatile metal MACT floor standard of 43 g/dscm
for new hazardous waste burning lightweight aggregate kilns.
6. What Are the Low Volatile Metals Standards?
In the final rule, we establish a standard for both existing and
new lightweight aggregate kilns that limits low volatile metal
emissions to 110 g/dscm. The rationale for adopting these
standards is discussed below.
a. What Is the MACT Floor for Existing Sources? In the April 1996
proposal, we defined floor control based on the performance of a fabric
filter with an air-to-cloth ratio of 1.8 acfm/ft2 and a
hazardous waste feedrate level of 46,000 g/dscm, expressed as
a maximum theoretical emissions concentration. The proposed floor
emission level was 340 g/dscm. (61 FR at 17405.) In the May
1997 NODA, we discussed a floor methodology where we used a breakpoint
analysis to identify sources that were not using floor control with
respect either to low volatile metals hazardous waste feedrate or
emissions control. Under this approach, we ranked low volatile metal
emissions data from sources that were achieving the particulate matter
floor level of 50 mg/dscm or better. We identified the floor level as
the test condition average associated with the breakpoint source. Thus,
sources with atypically high emissions because of high low volatile
feedrate levels or poor low volatile metals control were screened from
the pool of sources used to define the floor emission level. Based on
this analysis, we identified a floor emission level of 37 g/
dscm. (62 FR at 24234.)
We received few comments, in response to the April 1996 NPRM and
May 1997 NODA, concerning the low volatile metals floor emission level.
We received comments, however, on several overarching issues including
the appropriateness of considering feedrate control of metals
(including low volatile metals) in hazardous waste as a MACT floor
control technique and the specific procedure of identifying breakpoints
of arrayed emissions data. These issues and our responses to them are
discussed in the floor methodology section in Part Four, Section V.
For today's rule, we use a revised engineering evaluation and data
analysis method to establish the MACT floor level for low volatile
metals. The aggregate feedrate approach in conjunction with MACT
particulate matter control to 57 mg/dscm results in a low volatile
metal floor emission level of 110 g/dscm.
We estimate that over 80 percent of existing lightweight aggregate
kiln sources in our data base meet the floor level. The national
annualized compliance cost for lightweight aggregate kilns to reduce
low volatile metal emissions to comply with the floor emission level is
$52,000 for the entire hazardous waste burning lightweight aggregate
kiln industry, and will reduce low volatile metal emissions by 0.04 Mg/
yr or 40 percent from current baseline emissions.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the April 1996 NPRM and May 1997 NODA, we considered a
beyond-the-floor standard for low volatile metals based on improved
particulate matter control. However, we concluded that a beyond-the-
floor standard would not be cost-effective due to the high cost of
emissions control and relatively small amount of low volatile metals
removed from air emissions. (61 FR at 17406 and 62 FR at 24235.)
For today's rule, we identified three potential beyond-the-floor
techniques for control of low volatile metals: (1) Improved particulate
matter control; (2) limiting the feed of low volatile metals in the
hazardous waste; and (3) limiting the feed of low volatile metals in
the raw materials. The results of each analysis are discussed below.
Improved Particulate Matter Control. Our judgment is that a beyond-
the-floor standard based on improved particulate matter control would
be less cost-effective that a beyond-the-floor option based on limiting
the feedrate of low
[[Page 52899]]
volatile metals in the hazardous waste. Our data show that lightweight
aggregate kilns are already achieving a 99.9% system removal efficiency
of low volatile metals and some sources are even attaining 99.99%.
Thus, pollution control equipment retrofit costs for improved control
would be significant. Thus, we conclude a beyond-the-floor emission
level for low volatile metals based on improved particulate matter
control for lightweight aggregate kilns is not warranted.
Limiting the Feedrate of Low Volatile Metals in the Hazardous
Waste. We also considered a beyond-the-floor level of 70 g/
dscm based on additional feedrate control of low volatile metals in the
hazardous waste. Our investigation shows that this beyond-the-floor
option would achieve an incremental reduction in low volatile metals of
only 0.01 Mg/yr. Given that this beyond-the-floor level would not
achieve appreciable emissions reductions, significant cost-
effectiveness considerations would likely arise, thus suggesting that
this beyond-the-floor standard is not warranted.
Limiting the Feedrate of Low Volatile Metals in Raw Materials. A
source can achieve a reduction in low volatile metal emissions by
substituting a feed material containing lower levels of these metals
for a primary raw material higher low volatile metal levels. This
beyond-the-floor option appears to be less cost-effective compared to
either of the options evaluated above because lightweight aggregate
kilns are sited proximate to primary raw material supply. Transporting
large quantities of an alternative source of raw material(s) is
expected to be very costly and not cost-effective considering the
limited emissions reductions that would be achieved. Therefore, we do
not adopt this low volatile metals beyond-the-floor standard.
For reasons discussed above, we do not adopt a beyond-the-floor
level for low volatile metals, and establish the emissions standard for
existing hazardous waste burning lightweight aggregate kilns at 110
g/dscm.
c. What Is the MACT Floor for New Sources? At proposal, we defined
floor control based on the performance of a fabric filter with an air-
to-cloth ratio of 1.3 acfm/ft2 a hazardous waste feedrate
level of 37,000 g/dscm, expressed as a maximum theoretical
emissions concentration. The proposed floor level was 55 g/
dscm. (61 FR at 17408.) In the May 1997 NODA, we concluded that the
floor control and emission level for existing sources for low volatile
metals would also be appropriate for new sources. Floor control was
based on a combination of good particulate matter control and limiting
hazardous waste feedrate of low volatile metals to control emissions.
We used a breakpoint analysis of the low volatile metal emissions data
to exclude sources achieving substantially poorer low volatile metal
control than the majority of sources. The NODA floor was 37 g/
dscm. (62 FR at 24235.)
In the final rule, in response to general comments on the May 1997
NODA, we use a revised engineering evaluation and data analysis method
to establish the floor emission level for low volatile metals. We use
the aggregate feedrate approach in conjunction with floor control for
particulate matter of 57 mg/dscm to identify a low volatile metal floor
emission level of 110 g/dscm.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the April 1996 NPRM and May 1997 NODA, we considered a low volatile
metal beyond-the-floor level, but determined that a beyond-the-floor
standard would not be cost-effective due to the high cost of treatment
and relatively small amount of low volatile metals removed from air
emissions. We received no comments to the contrary.
For the final rule, as discussed for existing sources, we do not
adopt a beyond-the-floor level for new sources, and conclude that the
floor emission level is appropriate. Therefore, we adopt the low
volatile metal floor level of 110 g/dscm as the emission
standard for new hazardous waste burning lightweight aggregate kilns.
7. What Are the Hydrochloric Acid and Chlorine Gas Standards?
In the final rule, we establish a standard for existing and new
lightweight aggregate kilns that limits hydrochloric acid and chlorine
gas emissions to 230 and 41 ppmv, respectively. The rationale for
adopting these standards is discussed below.
a. What Is the MACT Floor for Existing Sources? In the April 1996
proposal, we identified floor control for hydrochloric acid/chlorine
gas as either: (1) Hazardous waste feedrate control of chlorine to 1.5
g/dscm, expressed as a maximum theoretical emissions concentration; or
(2) a combination of a venturi scrubber and hazardous waste feedrate
level of 14 g/dscm, expressed as a maximum theoretical emissions
concentration. The proposed floor emission level was 2100 ppmv. (61 FR
at 17406.) In the May 1997 NODA, we used the same data analysis method
as proposed, except that a computed emissions variability factor was no
longer added. The floor emission level was 1300 ppmv. (62 FR at 24235.)
We received few comments concerning the hydrochloric acid/chlorine
gas floor methodology and emission level. One commenter supports the
use of a variability factor in calculating the floor emission level.
Generally, the final emission standards, including hydrochloric acid/
chlorine gas, already accounts for emissions variability without adding
a statistically-derived emissions variability factor. This issue and
our response to it are discussed in detail in the floor methodology
section in Part Four, Section V.
For today's rule, we use a revised engineering evaluation and data
analysis method to establish the MACT floor level for hydrochloric acid
and chlorine gas. The aggregate feedrate approach results in a floor
emission level of 1500 ppmv.
We estimate that approximately 31 percent of lightweight aggregate
kilns in our data base currently meet the floor emission level. The
national annualized compliance cost for sources to reduce hydrochloric
acid and chlorine gas emissions to comply with the floor level is
$350,000 for the entire hazardous waste burning lightweight aggregate
kiln industry, and will reduce hydrochloric acid and chlorine gas
emissions by 182 Mg/yr or 10 percent from current baseline emissions.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the April 1996 proposal, we defined beyond-the-floor
control as wet or dry lime scrubbing with a control efficiency of 90
percent. We proposed a beyond-the-floor standard of 450 ppmv, which
included a statistical variability factor. (61 FR at 17406.) In the May
1997 NODA, the beyond-the-floor standard was 130 ppmv based on wet or
dry scrubbing with a control efficiency of 90 percent. (62 FR at
24235.)
We identified three potential beyond-the-floor techniques for
control of hydrochloric acid and chlorine gas emissions: (1) Dry lime
scrubbing; (2) limiting the feed of chlorine in the hazardous waste;
and (3) limiting the feed of chlorine in the raw materials. The result
of each analysis is discussed below.
Dry Lime Scrubbing. Based on a joint emissions testing program with
Solite Corporation in 1997, dry lime scrubbing at a stoichiometric lime
ratio of 3:1 achieved greater than 85 percent removal of hydrochloric
acid and chlorine gas. For the final rule, we considered a beyond-the-
floor emission level of 230 ppmv based on a 85 percent removal
efficiency from the floor level of 1500 ppmv.
[[Page 52900]]
The national incremental annualized compliance cost for all
lightweight aggregate kilns to meet this beyond-the-floor level is
approximately $1.5 million. This would provide an incremental reduction
in hydrochloric acid/chlorine gas emissions beyond the MACT floor
controls of an additional 1320 Mg/yr, or 80 percent. Based on these
costs of approximately $1,100 per additional Mg hydrochloric acid/
chlorine gas removed, this hydrochloric acid/chlorine gas beyond-the-
floor option for lightweight aggregate kilns is justified. Therefore,
we are adopting a beyond-the-floor standard of 230 ppmv for existing
lightweight aggregate kilns.
One commenter disagreed with our proposal to base the beyond-the-
floor standard on dry lime scrubbing achieving 90% removal. The
commenter states that dry lime scrubbing cannot cost-effectively
achieve 90 percent control of hydrochloric acid and chlorine gas
emissions. To achieve a 90 percent capture efficiency at a
stoichiometric ratio of 3:1, the commenter maintains that a source
would need to install special equipment and make operational
modifications that are less cost-effective than simple dry lime
scrubbing at a lower removal efficiency. The commenter identifies this
lower level of control at 80 percent based on the joint emissions
testing program.169 The commenter does agree, however, that
dry lime scrubbing can achieve 90 percent capture without the
installation of special equipment by operating at a stoichiometric lime
ratio greater than 3:1. One significant consequence of operating at
higher stoichiometric lime ratios, the commenter states, is the adverse
impact to the collected particulate matter. Currently, the collected
particulate matter is recycled into the lightweight aggregate product.
At higher stoichiometric lime ratios, unreacted lime and collected
chloride and sulfur salts would prevent this recycling practice and
would require the disposal of all the collected particulate matter at
significant and unjustified costs.
---------------------------------------------------------------------------
\169\ See ``Final Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999.
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We agree with the commenter that data from the joint emissions
testing program does not support a 90 percent capture efficiency by
simple dry lime scrubbing at a stoichiometric lime ratio of 3:1. We
disagree with the commenter that the data support an efficiency no
greater than 80 percent. In the testing program, we evaluated the
capture efficiency of lime during four runs at a stoichiometric lime
ratio of approximately 3:1. The results show that hydrochloric acid was
removed at rates ranging from 86 to 91 percent with one exception. For
that one run, the removal was calculated as 81 percent. For reasons
detailed in the Comment Response Document and in the technical support
document,170 we conclude that the data from this run should
not be considered because the calculated stoichiometric lime ratio is
suspect. When we remove this data point from consideration, the
available information clearly indicates that dry lime scrubbing at a
stoichiometric ratio of 3:1 can achieve greater than 85 percent
removal. Therefore, in the final rule, we base the beyond-the-floor
standard of 230 ppmv on 85 percent removal.
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\170\ See ``Final Technical Support Document for HWC MACT
Standards, Volume III: Selection of MACT Standards and
Technologies,'' July 1999.
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Limiting the Feedrate of Chlorine in the Hazardous Waste. We also
considered a beyond-the-floor standard for hydrochloric acid/chlorine
gas based on additional feedrate control of chlorine in the hazardous
waste. This option achieves lower emission reductions and is less cost-
effective than the dry lime scrubbing option discussed above.
Therefore, we are not adopting a hydrochloric acid/chlorine gas beyond-
the-floor standard based on limiting the feed of chlorine in the
hazardous waste.
Limiting the Feedrate of Chlorine in the Raw Materials. A source
can achieve a reduction in hydrochloric acid/chlorine gas emissions by
substituting a feed material containing lower levels of chlorine for a
primary raw material higher chlorine levels. This beyond-the-floor
option appears to be less cost effective compared to either of the
options evaluated above because lightweight aggregate kilns are sited
proximate to primary raw material supply. Transporting large quantities
of an alternative source of raw material(s) is expected to be very
costly and not cost-effective considering the limited emissions
reductions that would be achieved. Therefore, we do not adopt this
hydrochloric acid/chlorine gas beyond-the-floor standard.
In summary, we establish the hydrochloric acid/chlorine gas
standard for existing lightweight aggregate kilns at 230 ppmv based on
scrubbing.
c. What Is the MACT Floor for New Sources? In the April 1996
proposal, we defined MACT floor control for new sources as a venturi
scrubber with a hazardous waste feedrate level of 14 g/dscm, expressed
as a maximum theoretical emissions concentration. We proposed a floor
emission level of 62 ppmv. (61 FR at 17409.) In the May 1997 NODA, we
concluded that the floor control and emission level for existing
sources for hydrochloric acid/chlorine gas would also be appropriate
for new sources. Floor control was based on limiting hazardous waste
feedrates of chlorine to control hydrochloric acid/chlorine gas
emissions. We screened out some data with anomalous system removal
efficiencies compared to the majority of sources. The floor emission
level for new lightweight aggregate kilns was 43 ppmv. (62 FR at
24235.)
In the final rule, we use a similar engineering evaluation and data
analysis method as discussed in the May 1997 NODA to establish the
floor emission level for hydrochloric acid/chlorine gas. We identified
MACT floor control as wet scrubbing since the best controlled source is
using this control technology. One lightweight aggregate facility uses
venturi-type wet scrubbers for the control of hydrochloric acid/
chlorine gas. We evaluated the chlorine system removal efficiencies
achieved by wet scrubbing at this facility. Our data show that this
facility is consistently achieving greater than 99 percent control of
hydrochloric acid/chlorine gas. Because we have no data with system
removal efficiencies indicative of poor performance, we conclude that
all data from this facility are reflective of MACT control (wet
scrubbers), and, therefore, the floor emission limit for new sources is
set equal to the highest test condition average of these data. Thus,
the MACT floor emission limit for new lightweight aggregate kilns is
identified as 41 ppmv.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the April 1996 proposal and May 1997 NODA, we did not propose a beyond-
the-floor standard for new sources because the floor emission level was
based on wet scrubbing, which is the best available control technology
for hydrochloric acid/chlorine gas. (61 FR at 17409 and 62 FR at
24235.) We continue to believe that a beyond-the-floor emission level
for new sources is not warranted due to the high costs of treatment and
the small additional amount of chlorine that would be removed.
Therefore, the MACT standard for new lightweight aggregate kilns is
identified as 41 ppmv.
8. What Are the Hydrocarbon and Carbon Monoxide Standards?
In the final rule, we establish hydrocarbon and carbon monoxide
standards as surrogates to control emissions of nondioxin organic
hazardous air pollutants for existing and
[[Page 52901]]
new lightweight aggregate kilns. The standards limit hydrocarbon and
carbon monoxide concentrations to 20 ppmv 171 or 100 ppmv,
172 respectively. Existing and new lightweight aggregate
kilns can elect to comply with either the hydrocarbon limit or the
carbon monoxide limit on a continuous basis. Lightweight aggregate
kilns that choose to comply with the carbon monoxide limit on a
continuous basis must also demonstrate compliance with the hydrocarbon
standard during the comprehensive performance test. However, continuous
hydrocarbon monitoring following the performance test is not
required.173 We discuss the rationale for establishing these
standards below.
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\171\ Hourly rolling average, reported as propane, dry basis and
corrected to 7 percent oxygen.
\172\Hourly rolling average, dry basis, corrected to 7 percent
oxygen.
\173\As discussed in Part 5, Section X.F, lightweight aggregate
kilns that feed hazardous waste at a location other than the end
where products are normally discharged and where fuels are normally
fired must comply with the 20 ppmv hydrocarbon standards (i.e.,
these sources do not have the option to comply with the carbon
monoxide standard).
---------------------------------------------------------------------------
a. What Is the MACT Floor for Existing Sources? As discussed in
Part Four, Section II.A.2, we proposed limits on hydrocarbon and carbon
monoxide emissions as surrogates to control nondioxin organic hazardous
air pollutants. In the April 1996 NPRM, we identified floor control as
combustion of hazardous waste under good combustion practices to
minimize the generation of fuel-related hydrocarbons. We proposed a
hydrocarbon emission level of 14 ppmv and a carbon monoxide level of
100 ppmv. The hydrocarbon level was based on an analysis of the
available emissions data, while the basis of the carbon monoxide level
was existing federal regulations (see Sec. 266.104(b)). (61 FR at
17407.) In the May 1997 NODA, we solicited comment a hydrocarbon
emission level of 10 ppmv. The hydrocarbon floor level was changed to
10 ppmv from 14 ppmv because of a change in the lightweight aggregate
kiln universe of facilities. The lightweight aggregate kiln with the
highest hydrocarbon emissions stopped burning hazardous waste. With the
exclusion of the hydrocarbon data from this one source, the remaining
lightweight aggregate kilns appeared to be able to meet a hydrocarbon
standard on the order of 6 ppmv. However, since we were unable to
identify an engineering reason why lightweight aggregate kilns using
good combustion practices should be able to achieve lower hydrocarbon
emissions than incinerators, we indicated that it may be more
appropriate to establish the hydrocarbon standard at 10 ppmv, which was
equal to the incinerator emission level discussed in that NODA. In the
NODA, we also continued to indicate our preference for a carbon
monoxide emission level of 100 ppmv. (62 FR at 24235.)
One commenter states that some lightweight aggregate kilns may not
be able to meet a 10 ppmv hydrocarbon standard due to organics in raw
materials. Notwithstanding our data base of short-term data indicating
the achievability of a hydrocarbon standard of 10 ppmv, the commenter
states that this standard may be unachievable over the long-term
because trace levels of organic matter in the raw materials vary
significantly. Hydrocarbon emissions could increase as the source uses
raw materials from different on-site quarry locations. Thus, the
commenter supports a hydrocarbon emission level consistent with cement
kilns (i.e., 20 ppmv), and opposes a floor emission level that is
comparable to incinerators for which low temperature organics
desorption from raw materials is not a complicating issue.
Our limited hydrocarbon data, as discussed above, indicates that a
hydrocarbon level of 10 ppmv is achievable for lightweight aggregate
kilns.174 However, we agree that over long-term operations,
lightweight aggregate kilns may encounter variations in the level of
trace organics in raw materials, similar to cement kilns, that may
preclude some kilns from achieving a hydrocarbon limit of 10 ppmv.
Thus, we conclude that a hydrocarbon emission level of 20 ppmv, the
same floor level for cement kilns, is also appropriate for lightweight
aggregate kilns. A hydrocarbon standard of 20 ppmv also is based on
existing federally-enforceable RCRA regulations, to which lightweight
aggregate kilns are currently subject. (See Sec. 266.104(c).)
---------------------------------------------------------------------------
\174\ Our data base for hydrocarbons consists of short-term
emissions data.
---------------------------------------------------------------------------
Some commenters also support a requirement for both a carbon
monoxide and hydrocarbon limit for lightweight aggregate kilns. These
commenters state that requiring both hydrocarbon and carbon monoxide
limits would further reduce emissions of organic hazardous air
pollutants. One commenter notes that 83 percent of existing lightweight
aggregate kilns are currently achieving both a hydrocarbon level of 20
ppmv and a carbon monoxide standard of 100 ppmv.
We carefully considered the merits and drawbacks to requiring both
a hydrocarbon and carbon monoxide standard. First, stack gas carbon
monoxide levels may not be a universally reliable indicator of
combustion intensity and efficiency for some lightweight aggregate
kilns due, first, to carbon monoxide generation by disassociation of
carbon dioxide to carbon monoxide at high temperatures and, second, to
evolution of carbon monoxide from the trace organic constituents in raw
material feedstock.175 One commenter supports our view by
citing normal variability in carbon monoxide levels at their kiln with
no apparent relationship to combustion conditions, such as temperature,
residence time, excess oxygen levels. Thus, carbon monoxide can be
overly conservative surrogate for some kilns.176
---------------------------------------------------------------------------
\175\ Raw materials enter the upper end of the kiln and move
counter-current to the combustion gas. Thus, as the raw materials
are convectively heated in the upper end kiln above the flame zone,
organic compounds can evolve from trace levels of organics in the
raw materials. These organic compounds can be measured as
hydrocarbons, and when only partially oxidized, carbon monoxide.
This process is not related to combustion of hazardous waste or
other fuels in the combustion zone at the other end of the kiln.
\176\ Of course, if a source elects to comply with the carbon
monoxide standard, then we are sure that it is achieving good
combustion conditions and good control of organic hazardous air
pollutants that could be potentially emitted from hazardous waste
fed into the combustion zone.
---------------------------------------------------------------------------
Second, requiring both continuous monitoring of carbon monoxide and
hydrocarbon in the stack is at least somewhat redundant for control of
organic emissions from combustion of hazardous waste because: (1)
Hydrocarbons alone are a direct and reliable surrogate for measuring
the destruction of organic hazardous air pollutants; and (2) carbon
monoxide is generally a conservative indicator of good combustion
conditions and thus good control of organic hazardous air pollutants.
See Part Four, Section IV.B of the preamble for a discussion of our
approach to using carbon monoxide or hydrocarbons to control organic
emissions.
We identify a carbon monoxide level of 100 ppmv and a hydrocarbon
level of 20 ppmv as floor control for existing sources because they are
existing federally enforceable standards for hazardous waste burning
lightweight aggregate kilns. See Sec. 266.104(b) and (c). As current
rules allow, sources would have the option of complying with either
limit. Given that these are current rules, all lightweight aggregate
kilns can currently achieve these emission levels. Thus, we estimate no
emissions reductions or costs for these floor levels.
Lightweight aggregate kilns that choose to continuously monitor and
[[Page 52902]]
comply with the carbon monoxide standard must demonstrate during the
performance test that they are also in compliance with the hydrocarbon
emission standard. In addition, kilns that monitor carbon monoxide
alone must also set operating limits on key parameters that affect
combustion conditions to ensure continued compliance with the
hydrocarbon emission standard. We developed this modification because
of some limited data that show a source can produce high hydrocarbon
emissions while simultaneously producing low carbon monoxide emissions.
We conclude from this information that it is necessary to confirm the
carbon monoxide-hydrocarbon emissions relationship for every source
that selects to monitor carbon monoxide emissions alone. See discussion
in Part Four, Section IV.B.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? In the April 1996 proposal, we identified beyond-the-floor
control levels for carbon monoxide and hydrocarbon in the main stack of
50 ppmv and 6 ppmv, respectively. (61 FR at 17407.) These beyond-the-
floor levels were based on the use of a combustion gas afterburner. We
indicated in the proposal, however, that this type of beyond-the-floor
control would be cost prohibitive. Our preliminary estimates suggested
that going beyond-the-floor for carbon monoxide and hydrocarbons would
more than double the national costs of complying with the proposed
standards. We continue to believe that a beyond-the-floor standard for
carbon monoxide and hydrocarbons based on an afterburner is not
justified and do not adopt a beyond-the-floor standard for existing
lightweight aggregate kilns.
In summary, we adopt the floor emission levels for hydrocarbons, 20
ppmv, or carbon monoxide, 100 ppmv, as standards in the final rule.
c. What Is the MACT Floor for New Sources? In the April 1996 NPRM,
we identified MACT floor control as operating the kiln under good
combustion practices. Because we were unable to quantify good
combustion practices, floor control for the single best controlled
source was the same as for existing sources. We proposed, therefore, a
floor emission level of 14 ppmv for hydrocarbons and a 100 ppmv limit
for carbon monoxide. (61 FR at 17409.) In the May 1997 NODA, we
continued to identify MACT floor control as good combustion practices
and we took comment on the same emission levels as existing sources: 20
ppmv for hydrocarbons and 100 ppmv for carbon monoxide. (62 FR at
24235.)
In developing the final rule, we considered the comment that the
rule should allow compliance with either a carbon monoxide standard of
100 ppmv or a hydrocarbon standard of 20 ppmv. Given that this option
is available under the existing regulations for new and existing
sources, we conclude that this represents MACT floor for new sources.
These emission levels are achieved by operating the kiln under good
combustion practices to minimize fuel-related hydrocarbons and carbon
monoxide emissions. As current rules allow, sources would have the
option of complying with either limit. See Sec. 266.104(b) and (c).
We also considered site selection based on availability of
acceptable raw material hydrocarbon content as an approach to establish
a hydrocarbon emission level at new lightweight aggregate kilns. This
approach is similar to that done for new hazardous waste burning cement
kilns at greenfield sites (see discussion above). For cement kilns, we
finalize a new source floor hydrocarbon emission standard at a level
consistent with the proposed standard for nonhazardous waste burning
cement kilns. Because we are planning to issue MACT emission standards
for nonhazardous waste lightweight aggregate kiln sources, we will
revisit establishing a hydrocarbon standard at new lightweight
aggregate kilns at that time so that a hydrocarbon standard, if
determined appropriate, is consistent for these sources. We are
deferring this decision to a later date to ensure that hazardous waste
sources are regulated no less stringently than nonhazardous waste
lightweight aggregate kilns.
In summary, we are identifying a carbon monoxide level of 100 ppmv
and a hydrocarbon level of 20 ppmv as floor control for new sources
because they are existing federally enforceable standards for hazardous
waste burning lightweight aggregate kilns. As discussed for existing
sources above, lightweight aggregate kilns that choose to continuously
monitor and comply with the carbon monoxide standard must demonstrate
during the performance test that they are also in compliance with the
hydrocarbon emission standard.
d. What Are Our Beyond-the-Floor Considerations for New Sources? In
the April 1996 proposal, we identified beyond-the-floor emission levels
for hydrocarbons and carbon monoxide of 6 ppmv and 50 ppmv,
respectively for new sources. These beyond-the-floor levels were based
on the use of a combustion gas afterburner. (61 FR at 17409.) We
indicated in the proposal, however, that beyond-the-floor control was
not justified due to the significant costs to retrofit kilns with
afterburner controls. We estimated that going beyond-the-floor for
hydrocarbons and carbon monoxide would more than double the national
costs of complying with the proposed standards. We concluded that
beyond-the-floor standards were not warranted. In the May 1996 NODA, we
again indicated that a beyond-the-floor standard based on use of an
afterburner would not be cost-effective and, therefore, justified. As
discussed above for existing sources, we conclude that a beyond-the-
floor standard for carbon monoxide and hydrocarbons based on use of an
afterburner would not be justified and do not adopt a beyond-the-floor
standard for new lightweight aggregate kilns. (62 FR 24235.)
In summary, we adopt the floor emission levels for hydrocarbons, 20
ppmv, or carbon monoxide, 100 ppmv, as standards in the final rule.
9. What Are the Standards for Destruction and Removal Efficiency?
We establish a destruction and removal efficiency (DRE) standard
for existing and new lightweight aggregate kilns to control emissions
of organic hazardous air pollutants other than dioxins and furans.
Dioxins and furans are controlled by separate emission standards. See
discussion in Part Four, Section IV.A. The DRE standard is necessary,
as previously discussed, to complement the carbon monoxide and
hydrocarbon emission standards, which also control these hazardous air
pollutants.
The standard requires 99.99 percent DRE for each principal organic
hazardous constituent (POHC), except that 99.9999 percent DRE is
required if specified dioxin-listed hazardous wastes are burned. These
wastes--F020, F021, F022, F023, F026, and F027--are listed as RCRA
hazardous wastes under part 261 because they contain high
concentrations of dioxins.
a. What Is the MACT Floor for Existing Sources? Existing sources
are currently subject to DRE standards under Sec. 266.104(a) that
require 99.99 percent DRE for each POHC, except that 99.9999 percent
DRE is required if specified dioxin-listed hazardous wastes are burned.
Accordingly, these standards represent MACT floor. Since all hazardous
waste lightweight aggregate kilns must currently achieve these DRE
standards, they represent floor control.
b. What Are Our Beyond-the-Floor Considerations for Existing
Sources? Beyond-the-floor control would be a requirement to achieve a
higher
[[Page 52903]]
percentage DRE, for example, 99.9999 percent DRE for POHCs for all
hazardous wastes. A higher DRE could be achieved by improving the
design, operation, or maintenance of the combustion system to achieve
greater combustion efficiency.
Even though the 99.99 percent DRE floor is an existing RCRA
standard, a substantial number of existing hazardous waste combustors
are not likely to be routinely achieving 99.999 percent DRE, however,
and most are not likely to be achieving 99.9999 percent DRE.
Improvements in combustion efficiency will be required to meet these
beyond-the-floor DREs. Improved combustion efficiency is accomplished
through better mixing, higher temperatures, and longer residence times.
As a practical matter, most combustors are mixing-limited and may not
easily achieve 99.9999 percent DRE. For a less-than-optimum burner, a
certain amount of improvement may typically be accomplished by minor,
relatively inexpensive combustor modifications--burner tuning
operations such as a change in burner angle or an adjustment of swirl--
to enhance mixing on the macro-scale. To achieve higher DREs, however,
improved mixing on the micro-scale may be necessary. This involves
significant, energy intensive and expensive modifications such as
burner redesign and higher combustion air pressures. In addition,
measurement of such DREs may require increased spiking of POHCs and
more sensitive stack sampling and analysis methods at added expense.
Although we have not quantified the cost-effectiveness of a beyond-
the-floor DRE standard, it would not appear to be cost-effective. For
reasons discussed above, the cost of achieving each successive order-
of-magnitude improvement in DRE will be at least constant, and more
likely increasing. Emissions reductions diminish substantially,
however, with each order of magnitude improvement in DRE. For example,
if a source were to emit 100 gm/hr of organic hazardous air pollutants
assuming zero DRE, it would emit 10 gm/hr at 90 percent DRE, 1 gm/hr at
99 percent DRE, 0.1 gm/hr at 99.9 percent DRE, 0.01 gm/hr at 99.99
percent DRE, and 0.001 gm/hr at 99.999 percent DRE. If the cost to
achieve each order of magnitude improvement in DRE is roughly constant,
the cost-effectiveness of DRE decreases with each order of magnitude
improvement in DRE. Consequently, we conclude that this relationship
between compliance cost and diminished emissions reductions suggests
that a beyond-the-floor standard is not warranted in light of the
resulting, poor cost-effectiveness.
c. What Is the MACT Floor for New Sources? The single best
controlled source, and all other hazardous waste lightweight aggregate
kilns, are subject to the existing RCRA DRE standard under
Sec. 266.104(a). Accordingly, we adopt this standard of 99.99% DRE for
most wastes and 99.9999% DRE for dioxin listed wastes as the MACT floor
for new sources.
d. What Are Our Beyond-the-Floor Considerations for New Sources? As
discussed above, although we have not quantified the cost-effectiveness
of a more stringent DRE standard, diminishing emissions reductions with
each order of magnitude improvement in DRE suggests that cost-
effectiveness considerations would likely come into play. We conclude
that a beyond-the-floor standard is not warranted.
Part Five: Implementation
I. How Do I Demonstrate Compliance with Today's Requirements?
If you operate a hazardous waste burning incinerator, cement kiln,
or lightweight aggregate kiln, you are required to comply with the
standards and requirements in today's rule at all times, with one
exception. If you are not feeding hazardous waste to the combustion
device and if hazardous waste does not remain in the combustion
chamber, these rules do not apply under certain conditions discussed
below. You must comply with all of the notification requirements,
emission standards, and compliance and monitoring provisions of today's
rule by the compliance date, which is three years after September 30,
1999. As referenced later, the effective date of today's rule is
September 30, 1999. The compliance and general requirements of this
rule are discussed in detail in the follow sections. Also, we have
included the following time line that will assist you in determining
when many of the notifications and procedures, discussed in the later
sections of this part, are required to be submitted or accomplished.
A. What Sources Are Subject to Today's Rules?
Sources affected by today's rule are defined as all incinerators,
cement kilns and lightweight aggregate kilns burning hazardous waste
on, or following September 30, 1999. This definition is essentially the
same as we proposed in the April 1996 NPRM. Comments, regarding this
definition, suggested that there was confusion as to when and under
what conditions you would be subject to today's hazardous waste MACT
regulations. In this rule, we specify that once you are subject to
today's regulations, you remain subject to these regulations until you
comply with the requirements for sources that permanently suspend
hazardous waste burning operations, as discussed later.
However, just because you are subject to today's regulations does
not mean that you must comply with the emission standards or operating
limits at all times. In later sections of today's rule, we identify
those limited periods and situations in which compliance with today's
emission standards and operating limits may not be required.
1. What Is an Existing Source?
Today's rule clarifies that existing sources are sources that were
constructed or under construction on the publication date for our
NPRM---April 19, 1996. This is consistent with the current regulatory
definition of existing sources, but is different from the definition in
our April 1996
NPRM. In the April 1996 NPRM, we defined existing sources as those
burning hazardous waste on the proposal date (April 19, 1996) and
defined new sources as sources that begin burning hazardous waste after
the proposal date. Commenters note that the proposed definition of new
sources is not consistent with current regulations found in 40 CFR part
63 or the Clean Air Act. Commenters also believe that our definition
does not consider the intent of Congress, i.e., to require only those
sources that incur significant costs during upgrade or modification to
meet the most stringent new source emission standards. Commenters note
that a large number of sources that are currently not burning hazardous
waste could modify their combustion units to burn hazardous waste at a
cost that would not surpass the reconstruction threshold and therefore
they should not be required to meet the new source emission standards.
Commenters suggest we use the statutory definition of an existing
source found at section 112(a)(4) of the CAA and codified at 40 CFR
63.2. We agree with commenters and therefore adopt the definition of an
existing source found at 40 CFR 63.2.
2. What Is a New Source?
Today's rule clarifies that new sources are those that commence
construction or meet the definition of a reconstructed source following
the proposal date of April 19, 1996. In the proposal, we define new
sources as those that newly begin to burn hazardous waste after the
proposal date. However, as noted earlier, commenters object to the
[[Page 52904]]
proposed definition because of conflicts with the statutory language of
the CAA and the current definition found in MACT regulations. In the
CAA regulations, we define new sources as those that are newly
constructed or reconstructed after a rule is proposed. Here again, we
agree with commenters and adopt the current regulatory definition of
new sources. We also adopt the CAA definition of reconstruction. This
definition also is generally consistent with the RCRA definition of
reconstruction and should avoid any confusion regarding what standards
apply to reconstructed sources.
B. How Do I Cease Being Subject to Today's Rule?
Once you become an affected source as defined in Sec. 63.2, you
remain an affected source until you: (1) Cease hazardous waste burning
operations, (i.e., hazardous waste is not in the combustion chamber);
(2) notify the Administrator, and other appropriate regulatory
authorities, that you have ceased hazardous waste burning operations;
and (3) begin complying with other applicable MACT standards and
regulations, if any, including notifications, monitoring and
performance tests requirements.
If you permanently stop burning hazardous waste, the RCRA
regulations require you to initiate closure procedures within three
months of the date you received your last shipment of hazardous waste,
unless you have obtained an extension from the Administrator. The
requirement to initiate closure pertains to your RCRA status and should
not be a barrier to operational changes that affect your regulatory
status under today's MACT requirements. This approach is a departure
from the requirements proposed in the April 1996 NPRM, but is
consistent with the approach we identified in the May 1997 NODA.
Once you permanently stop burning hazardous waste, you may only
begin burning hazardous waste under the procedures outlined for new or
existing sources that become affected sources following September 30,
1999. See later discussion.
C. What Requirements Apply If I Temporarily Cease Burning Hazardous
Waste?
Under today's rule, if you temporarily cease burning hazardous
waste for any reason, you remain subject to today's requirements as an
affected source. However, even as an affected source, you may not have
to comply with the emission standards or operating limits of today's
rule when hazardous waste is not in the combustion chamber. Today's
standards, associated operating parameter limits, and monitoring
requirements are applicable at all times unless hazardous waste is not
in the combustion chamber and either: (1) You elect to comply with
other MACT standards that would be applicable if you were not burning
hazardous waste (e.g. the nonhazardous waste burning Portland Cement
Kiln MACT, the nonhazardous waste burning lightweight aggregate kiln
MACT (Clay Products Manufacturing), or the Industrial Incinerator
MACT); or (2) you are in a startup, shutdown, or malfunction mode of
operation. We note that until these alternative MACT standards are
promulgated, you need to comply only with other existing applicable air
requirements if any. This approach is consistent with the current RCRA
regulatory approach for hazardous waste combustion sources, but differs
from our April 1996 proposed approach.
In our April 1996 NPRM, we proposed that sources always be subject
to all of the proposed regulatory requirements, regardless of whether
hazardous waste was in the combustion chamber. Commenters question the
legitimacy of this requirement because the requirement was: (1) more
stringent than current requirements; (2) not based on CAA statutory
authority; and (3) contrary to current allowances under current MACT
general provisions.
In response, we agree with commenters on issues (1) and (3) above.
However, we disagree with commenters on issue number (2). The CAA does
not allow sources to be subject to multiple MACT standards
simultaneously. Because current CAA regulations also allow sources to
modify their operations such that they can become subject to different
MACT rules so long as they provide notification to the Administrator,
our proposed approach appears to further complicate a situation that it
was intended to resolve. One of the main reasons we proposed to subject
hazardous waste burning sources to the final standards at all times was
to eliminate the ability of sources to arbitrarily switch between
regulation as a hazardous waste burning source and regulation as a
nonhazardous waste burning source. We were concerned about the
compliance implications associated with numerous notifications to the
permitting authority to govern operations that may only occur for a
short period of time. However, our concern appears unfounded because
the MACT general provisions currently allow sources to change their
regulatory status following notification, and we cannot achieve this
goal without restructuring the entire MACT program. Therefore,
consistent with the current program, we adopt an approach that allows a
source to comply with alternative compliance requirements, while
remaining subject to today's rule. This regulatory approach eliminates
the reporting requirements and compliance determinations we intended to
avoid with our proposed approach, while preserving the essence of the
current RCRA approach, which applies more stringent emissions standards
when hazardous waste is in the combustor.
1. What Must I Do to Comply with Alternative Compliance Requirements?
If you wish to comply with alternative compliance requirements, you
must: (1) Comply with all of the applicable notification requirements
of the alternative regulation; (2) comply with all the monitoring,
record keeping and testing requirements of the alternative regulation;
(3) modify your Notice Of Compliance (or Documentation of Compliance)
to include the alternative mode(s) of operation; and (4) note in your
operating record the beginning and end of each period when complying
with the alternative regulation.
If you intend to comply with an alternative regulation for longer
than three months, then you also must comply with the RCRA requirements
to initiate RCRA closure. You may be able to obtain an extension of the
date you are required to begin RCRA closure by submitting a request to
the Administrator.
2. What Requirements Apply If I Do Not Use Alternative Compliance
Requirements?
If you elect not to use the alternative requirements for compliance
during periods when you are not feeding hazardous waste, you must
comply with all of the operating limits, monitoring requirements, and
emission standards of this rule at all times.177 However, if
you are a kiln operator, you also may be able to obtain and comply with
the raw material variance discussed later.
---------------------------------------------------------------------------
\177\ The operating requirements do not apply during startup,
shutdown, or malfunction provided that hazardous waste is not in the
combustion chamber. See the discussion below in the text.
---------------------------------------------------------------------------
D. What Are the Requirements for Startup, Shutdown and Malfunction
Plans?
Sources affected by today's rule are subject to the provisions of
40 CFR 63.6 with regard to startup, shutdown and malfunction plans.
However, the plan applies only when hazardous waste is
[[Page 52905]]
not in the combustion chamber. If you exceed an operating requirement
during startup, shutdown, or malfunction when hazardous waste is in the
combustion chamber, your exceedance is not excused by following your
plan. If you exceed an operating requirement during startup, shutdown,
or malfunction when hazardous waste is not in the combustion chamber,
you must follow your startup, shutdown, and malfunction plan to come
back into compliance as quickly as possibly, unless you have elected to
comply with the requirements of alternative section 112 or 129
regulations that would apply if you did not burn hazardous waste.
Failure to comply with the operating requirements to follow your
startup, shutdown, and malfunction plan during the applicable periods
is representative of a violation and may subject you to appropriate
enforcement action.
In the April 1996 NPRM (see 63 FR at 17449), we proposed that
startup, shutdown, and malfunction plans would not be applicable to
sources affected by the proposed rule because affected sources must be
in compliance with the standards at all times hazardous waste is in the
combustion chamber. We reasoned that hazardous waste could not be fired
unless you were in compliance with the emission standards and operating
requirements, and stated that the information contained in the plan and
the purpose of the plan was not intended to apply to sources affected
by this rule.
In response, commenters state that startup, shutdown, and
malfunction plans are appropriate for hazardous waste burning sources
because malfunctioning operations are going to occur, and these plans
are designed to reestablish compliant or steady state operations as
quickly as possible. Furthermore, commenters maintain that because
sources must prepare and follow facility-specific plans to address
situations that could lead to increased emissions, rather than just
note such an occurrence in the operating record, the public and we are
better assured that the noncompliant operations are being remedied
rather than awaiting for an after-the-fact enforcement action.
Commenters also note that hazardous waste burning sources are no
different than other MACT sources who are required to use such plans.
After considering comments, we agree with commenters that startup,
shutdown, and malfunction plans are valuable compliance tools and
should be applicable to hazardous waste burning sources. However, we
are concerned that some sources may attempt to use startup, shutdown,
and malfunction plans to circumvent enforcement actions by claiming
they were never out of compliance if they followed their plan.
Therefore, we restrict the applicability of startup, shutdown, and
malfunction plans to periods when hazardous waste is not in the
combustion chamber. This restriction addresses the concern that
operations under startup, shutdown, and malfunction could lead to
increased emissions of hazardous air pollutants.
We considered whether to specifically prohibit sources from feeding
hazardous waste during periods of startup and shutdown. However, we
decided not to adopt this requirement because of a potential regulatory
problem. The requirement could have inadvertently subjected sources
that experience unscheduled shutdowns to enforcement action if
hazardous waste remained in the combustion chamber during the shutdown
process even if operating requirements were not exceeded. Additionally,
we decided that the prohibition was unnecessary because performance
test protocols restrict the operations of all sources when determining
operating parameter limits. The following factors are pertinent in this
regard: (1) Sources are required to be in compliance with their
operating parameter limits at all times hazardous waste is in the
combustion chamber; (2) operating parameter limits are determined
through a performance test which must be performed under steady-state
conditions (see Sec. 63.1207(g)(1)(iii)); and (3) periods of startup
and shutdown are not steady state conditions and therefore operating
parameter limits determined through performance testing would not be
indicative of those periods. Accordingly, burning hazardous waste
during startup or shutdown would significantly increase the potential
for a source to exceed an operating parameter limit, and we expect that
sources would be unwilling to take that chance as a practical matter.
E. What Are the Requirements for Automatic Waste Feed Cutoffs?
As proposed, you must operate an automatic waste feed cutoff system
that immediately and automatically cuts off hazardous waste feed to the
combustion device when:
(1) Any of the following are exceeded: Operating parameter limits
specified in Sec. 63.1209; an emission standard monitored by a
continuous emissions monitoring system; and the allowable combustion
chamber pressure; (2) The span value of any continuous monitoring
system, except a continuous emissions monitoring system, is met or
exceeded; (3) A continuous monitoring system monitoring an operating
parameter limit under Sec. 63.1209 or emission level malfunctions; or
(4) Any component of the automatic waste feed cutoff system fails.
These requirements are provided at Sec. 63.1206(c)(3). The system
must be fully functional on the compliance date and interlocked with
the operating parameter limits you specify in the Document of
Compliance (as discussed later) as well as the other parameters listed
above.
Also as proposed, after an automatic waste feed cutoff, you must
continue to route combustion gases through the air pollution control
system and maintain minimum combustion chamber temperature as long as
hazardous waste remains in the combustion chamber. These requirements
minimize emissions of regulated pollutants, including organic hazardous
air pollutants, that could result from a perturbation caused by the
waste feed cutoff. Additionally, you must continue to calculate all
rolling averages and cannot restart feeding hazardous waste until all
operating limits are within allowable levels.
Additionally, as currently required for BIFs, we proposed that the
automatic waste feed cutoff system and associated alarms must be tested
at least once every seven days. This must be done when hazardous waste
is burned to verify operability, unless you document in the operating
record that weekly inspections will unduly restrict or upset operations
and that less frequent inspections will be adequate. At a minimum, you
must conduct operational testing at least once every 30 days.
Commenters express the following concerns with the proposed
automatic waste feed cutoff requirements: (1) Violations of the
automatic waste feed cutoff linked operating parameters should not
constitute a violation of the associated emission standard; (2)
apparent redundancy exists between the proposed MACT requirements with
the current RCRA requirements; (3) the proposed automatic waste feed
cutoff requirements are inappropriate for all sources; and (4)
uncertainty exists about how ``instantaneous'' is defined with regard
to the nature of the automatic waste feed cutoff requirement.
We address issue (1) later in this section. With respect to issue
(2), our permitting approach (i.e., a single CAA title V permit to
control all stack emissions) minimizes the potential redundancy of two
permitting programs.
In response to issue (3), we acknowledge that not all sources may
be capable of setting operating limits or
[[Page 52906]]
continuously monitoring all of the prescribed operating parameters due
to unique design characteristics inherent to individual units. However,
you may take advantage of the provisions found in Sec. 63.8(f) which
allow you to request the use of alternative monitoring techniques. See
also Sec. 63.1209(g)(1).
For issue (4), commenters express concern that requiring an
immediate, instantaneous, and abrupt cutoff of the entire waste feed
can cause perturbations in the combustion system that could result in
exceedances of additional operating limits. We agree with commenters
that a ramping down of the waste feedrate could preclude this problem
in many cases and in the final rule allow a one-minute ramp down for
pumpable wastes. To ensure that your ramp down procedures are bona fide
and not simply a one-minute delay ending in an abrupt cutoff, you must
document your ramp down procedures in the operating and maintenance
plan. The procedures must specify that the ramp down begins immediately
upon initiation of automatic waste feed cutoff and provides for a
gradual ramp down of the hazardous waste feed. Note that if an emission
standard or operating limit is exceeded during the ramp down, you
nonetheless have failed to comply with the emission standards or
operating requirements. The ramp down is not applicable, however, if
the automatic waste feed cutoff is triggered by an exceedance of any of
the following operating limits: minimum combustion chamber temperature;
maximum hazardous waste feedrate; or any hazardous waste firing system
operating limits that may be established for your combustor on a site-
specific basis. This is because these operating conditions are
fundamental to proper combustion of hazardous waste and an exceedance
could quickly result in an exceedance of an emission standard. We
restrict the ramp down to pumpable wastes because: (1) Solids are often
fed in batches where ramp down is not relevant (i.e., ramp down is only
relevant to continuously fed wastes); and (2) incinerators burning
solids also generally burn pumpable wastes and ramping down on
pumpables only should preclude the combustion perturbations that could
occur if all wastes were abruptly cutoff.
Finally, with respect to issue number (1), if you exceed an
operating parameter limit while hazardous waste is in the combustion
chamber, then you have failed to ensure compliance with the associated
emission standard. Accordingly, appropriate enforcement action on the
exceedance can be initiated to address the exceedance. This enforcement
process is consistent with current RCRA enforcement procedures
regarding exceedances of operating parameter limits. However, as
commenters note, we acknowledge that an exceedance of an operating
parameter limit does not necessarily demonstrate that an associated
emissions standard is exceeded. Nevertheless, in general, an exceedance
of an operating parameter limit in a permit or otherwise required is an
actionable event for enforcement purposes.
Operating parameter limits are developed through performance tests
that successfully demonstrate compliance with the standards. If a
source exceeds an operating limit set during the performance test to
show compliance with the standard, the source can no longer assure
compliance with the associated standard. Furthermore, these operating
parameter limits appear in enforceable documents, such as your NOC or
your title V permit.
F. What Are the Requirements of the Excess Exceedance Report?
In today's rule, we finalize the requirement to report to the
Administrator when you incur 10 exceedances of operating parameter
limits or emissions standards monitored with a continuous emissions
monitoring system within a 60 day period. See Sec. 63.1206(c)(3)(vi).
If a source has 10 exceedances within the 60 day period, the 60 day
period restarts after the notification of the 10th exceedance. This
provision is intended to identify sources that have excess exceedances
due to system malfunction or performance irregularities. This
notification requirement both highlights the source to regulatory
officials and provides an added impetus to the facility to correct the
problem(s) that may exist to limit future exceedances. For example, a
source that must submit an excess exceedance report may be unable to
operate under its current operating limits, which suggests that the
source may need to perform a new comprehensive performance test to
establish more appropriate operating limits.
We discussed this provision in the April 1996 NPRM. Some commenters
may have misunderstood our proposal while others felt that 10
exceedances in sixty days was not a feasible number to set the
reporting limit. Other commenters state that an industry wide MACT-like
analysis is necessary to identify an achievable or appropriate number
of exceedances upon which to set the reporting limit.
We disagree with such comments. A MACT-like analysis is not called
for in this case because this requirement is not an emission standard.
This is a notification procedure that is a compliance tool to identify
sources that cannot operate routinely in compliance with their
operating parameter limits and emissions standards monitored with a
continuous emissions monitoring system. Ideally, all sources should
operate in compliance with all the standards and operating parameter
limits at all times. Because, in the past, sources have been able to
exceed their operating limits without having to notify the Agency, this
does not mean that we condone, expect, or are unconcerned with such
activity. In fact, the main reason we require this notification is
because such activity exists to the current extent and because the
Regions and States have identified it as a problem. We select 10
exceedances in sixty days as the value that triggers reporting after
discussions with Regional and State permit writers. Our discussions
revealed that many hazardous waste combustion sources are required to
notify regulatory officials following a single exceedance of an
operating limit, while others don't have any reporting requirements
linked to exceedances. Regions and States noted that because there is
no current regulatory requirement for exceedance notifications, it is
very difficult to require such notifications on a site-specific basis.
Following these discussions, we contemplated requiring a notification
following a single exceedance, but decided that the such a reporting
limit might unnecessarily burden regulatory officials with reports from
facilities that have infrequent exceedances. Therefore, our approach of
10 exceedances in a 60 day period is a reasonably implementable limit
and is not overly burdensome. Adopting this approach achieves an
appropriate balance between burden on facilities and regulators and the
need to identify underlying operational problems that may present
unacceptable risks to the public and environment.
To reiterate, this provision applies to any 10 exceedances of
operating parameter limits or emission standards monitored with a
continuous emissions monitoring system.
G. What Are the Requirements for Emergency Safety Vent Openings?
In today's rule, we finalize requirements that govern the operation
of emergency safety vents. See Sec. 63.1206(c)(4). These requirements:
clarify the regulatory status of emergency safety vent events; require
[[Page 52907]]
development of an emergency safety vent operating plan that specifies
procedures to minimize the frequency and duration of emergency safety
vent openings; and specify procedures to follow when an emergency
safety vent opening occurs.
Key requirements regarding emergency safety vent openings include:
(1) Treatment of combustion gases--As proposed, you must route
combustion system off-gases through the same emission control system
used during the comprehensive performance test. Any bypass of the
pollution control system is considered an exceedance of operating
limits defined in the Documentation of Compliance (DOC) or Notification
of Compliance (NOC);
(2) Emergency safety vent operating plan--As proposed, if you use
an emergency safety vent in your system design, you must develop and
submit with the DOC and NOC an emergency safety vent operating plan
that outlines the procedures you will take to minimize the frequency
and duration of emergency safety vent openings and details the
procedure you will follow during and after an emergency safety vent
opening; and
(3) Emergency safety vent reporting requirements--As proposed, if
you operate an emergency safety vent, you must submit a report to the
appropriate regulatory officials within five days of an emergency
safety vent opening. In that report, you must detail the cause of the
emergency safety vent opening and provide information regarding
corrective measures you will institute to minimize such events in the
future.
Commenters on the April 1996 NPRM (61 FR at 17440) state that
emergency safety vent openings are safety devices designed to prevent
catastrophic failures, safeguard the unit and operating personnel from
pressure excursions and protect the air pollution control train from
high temperatures and pressures. They suggest that restricting these
operations is contrary to common sense. Furthermore, they state that
emergency safety vent openings are most often due to local power
outages and fluctuations in water flows going to the air pollution
equipment. Commenters believe that emergency safety vent openings
should not be considered violations and that not every emergency safety
vent opening should be reportable for a variety of reasons including:
--Emergency safety vent openings have not been shown to be acutely
hazardous. A study finds that they will not have any short-term impact
on the health of workers on-site or residents of the nearby off-site
community.
--Proper use of emergency safety vent systems minimizes the potential
for impacts on operators and the neighboring public.
--Many emergency safety vents are downstream of the secondary
combustion chamber and thus have low organic emissions.
--Some facilities have emergency safety vents connected to the air
pollution control system and should be considered in compliance as long
as the continuous emissions monitoring systems monitoring data does not
indicate an exceedance.
Commenters propose several alternatives:
--Recording emergency safety vent openings (including the time,
duration and cause of each event) in the operating record, available to
the Administrator, or any authorized representative, upon request.
--Making emergency safety vent openings a part of startup, shutdown,
malfunction and abatement plans.
--Reporting openings that occurs more frequently than once in any 90
day period, whereupon the Administrator may require corrective
measures.
--Reporting only emergency safety vent openings in excess of 10 in a 60
day period.
--Conditions relating to an emergency safety vent operation should be a
part of the site-specific permit.
--Rely on the present RCRA permit process which provides the
opportunity for permit writers and hazardous waste combustion device
owner/operators to review emergency safety vent system designs.
We agree that emergency safety vents are necessary safety devices
for some incinerator designs that are intended to safeguard employees
and protect the equipment from the dangers associated with system over-
pressures or explosions. However, simply because emergency safety vents
are necessary safety devices for some incinerator designs in the event
of a major malfunction does not mean that their routine use is
acceptable. We cannot overlook an event when combustion gases are
emitted into the environment prior to proper treatment by the pollution
control system. Therefore, an emergency safety vent opening is evidence
that compliance is not being achieved. Nonetheless, we expect sources
to continue to use safety vents when the alternative could be a
catastrophic failure and substantial liability even though opening the
vent is evidence of failure to comply with the emission standards.
Today's requirements are based on the fundamental need to ensure
protection of human health and the environment against unquantified and
uncontrolled hazardous air pollutant emissions. We do not agree that a
change in the proposed emergency safety vent reporting requirement is
warranted. These events are indicative of serious operational problems,
and each event should be reported and investigated to reduce the
potential of future similar events. As for including the emergency
safety vent operating plan in the source-specific startup, shutdown,
and malfunction plan, we see no reason to discourage that practice
provided that a combined plan specifically addresses the events
preceding and following an emergency safety vent opening.
H. What Are the Requirements for Combustion System Leaks?
You must prevent leaks of gaseous, liquid or solid materials from
the combustion system when hazardous waste is being fed to or remains
in the combustion chamber. To demonstrate compliance with this
requirement you must either: (1) Maintain the combustion system
pressure lower than ambient pressure at all times; (2) totally enclose
the system; or (3) gain approval from the Administrator to use an
alternative approach that provides the same level of control achieved
by options 1 and 2.
Currently, these requirements exist for all sources under RCRA
regulations. Many commenters question whether they were capable of
meeting this requirement for various technical reasons. We acknowledge
that certain situations may exist that prevent or limit a source from
instantaneously monitoring pressure inside the combustion system, but
in such situations, we can approve alternative techniques (under
Sec. 63.1209(g)(1)) that allow sources to achieve the objectives of the
requirements. Because this requirement is identical to the current RCRA
requirements, and because we have specifically provided alternative
techniques to demonstrate compliance, modifications to this provision
are not warranted.
I. What Are the Requirements for an Operation and Maintenance Plan?
You must prepare and at all times operate according to a operation
and maintenance plan that describes in detail procedures for operation,
inspection, maintenance, and corrective measures for all components of
the combustor, including associated pollution control equipment, that
could affect emissions of regulated hazardous
[[Page 52908]]
air pollutants. The plan must prescribe how you will operate and
maintain the combustor in a manner consistent with good air pollution
control practices for minimizing emissions at least to the levels
achieved during the comprehensive performance test. You must record the
plan in the operating record. See Sec. 63.1206(c)(7)(i).
In addition, if you own or operate a hazardous waste incinerator or
hazardous waste burning lightweight aggregate kiln equipped with a
baghouse, your operation and maintenance plan for the baghouse must
include a prescribed inspection schedule for baghouse components and
use of a bag leak detection system to identify malfunctions. This
baghouse operation and maintenance plan must be submitted to the
Administrator with the initial comprehensive performance test for
review and approval. See Sec. 63.1206(c)(7)(ii).
We require an operation and maintenance plan to implement the
provisions of Sec. 63.6(e). That paragraph requires you to operate and
maintain your source in a manner consistent with good air pollution
control practices for minimizing emissions. That paragraph, as all
Subpart A requirements, applies to all MACT sources unless requirements
in the subpart for a source category state otherwise. In addition,
Sec. 63.6(e)(2) states that the Administrator will determine whether
acceptable operation and maintenance procedures are used by reviewing
information including operation and maintenance procedures and records.
Thus, paragraph (e)(2) effectively requires you to develop operation
and maintenance procedures. Consequently, explicitly requiring you to
develop an operation and maintenance plan is a logical outgrowth of the
proposed rule.
Similarly, although we did not prescribe baghouse inspection
requirements or require a bag leak detection system at proposal for
incinerators and lightweight aggregate kilns, this is a logical
outgrowth of the proposed rule. Section 63.6(e) requires sources to
operate and maintain emission control equipment in a manner consistent
with good air pollution control practices for minimizing emissions.
Inspection of baghouse components is required to provide adequate
maintenance, and a bag leak detection system is a state-of-the-art
monitoring system that identifies major baghouse malfunctions. Absent
use of a particulate matter CEMS or opacity monitor, use of a bag leak
detection system is an essential monitoring approach to ensure that the
baghouse continues to operate in a manner consistent with good air
pollution control practices. Bag leak detection systems are required
under the MACT standards for secondary lead smelters. See Sec. 63.548.
We have also proposed to require them as MACT requirements for several
other source categories including primary lead smelters (see 63 FR
19200 (April 17, 1998)) and primary copper smelters (see 63 FR 19581
(April 20, 1998)). In addition, we have published a guidance document
on the installation and use of bag leak detection systems: USEPA,
``Fabric Filter Bag Leak Detection,'' September 1997, EPA-454/R-98-015.
Thus, although not explicitly required at proposal, a requirement to
use bag leak detection systems is a logical outgrowth of the (proposed)
requirements of Sec. 63.6(e).
We are not prescribing a schedule for inspection of baghouse
components or requiring a bag leak detection system for cement kilns
because cement kilns must use a continuous opacity monitoring system
(COMS) to demonstrate compliance with an opacity standard. A COMS is a
better indicator of baghouse performance than a bag leak detection
system. We could not use COMS for incinerators and lightweight
aggregate kilns, however, because we do not have data to identify an
opacity standard that is achievable by MACT sources (i.e., sources
using MACT control and achieving the particulate matter standard).
We are not specifying the type of sensor that must be used other
than: (1) The system must be certified by the manufacturer to be
capable of detecting particulate matter emissions at concentrations of
1.0 milligram per actual cubic meter; and (2) the sensor must provide
output of relative particulate matter loadings. Several types of
instruments are available to monitor changes in particulate emission
rates for the purpose of detecting fabric filter bag leaks or similar
failures. The principles of operation of these instruments include
electrical charge transfer and light scattering. The guidance document
cited above applies to charge transfer monitors that use
triboelectricity to detect changes in particle mass loading, but other
types of monitors may be used. Specifically, opacity monitors may be
used.
The economic impacts of requiring fabric filter bag leak detection
systems are minimal. These systems are relatively inexpensive. They
cost less than $11,000 to purchase and install. Further, we understand
that most hazardous waste burning lightweight aggregate kilns are
already equipped with triboelectric sensors. Finally, there are few
hazardous waste incinerators that are currently equipped with fabric
filters.
II. What Are the Compliance Dates for this Rule?
A. How Are Compliance Dates Determined?
In today's rule, as with other MACT rules, we specify the
compliance date and then provide you additional time to demonstrate
compliance through performance testing. Generally, you must be in
compliance with the emission standards on September 30, 2002 unless you
are granted a site-specific extension of the compliance date of up to
one year. By September 30, 2002, you must complete modifications to
your unit and establish preliminary operating limits, which must be
included in the Documentation of Compliance (DOC) and recorded in the
operating record. Following the compliance date you have up to 180 days
to complete the initial comprehensive performance test and an
additional 90 days to submit the results of the performance test in the
Notification of Compliance (NOC). In the NOC, you also must certify
compliance with applicable emission standards and define the operating
limits that ensure continued compliance with the emission standards.
In the April 1996 NPRM, we proposed that sources comply with all
the substantive requirements of the rule on the compliance date. This
required sources to conduct their performance test as well as submit
results in the NOC by the compliance date. The compliance date
discussed in the April 1996 NPRM contained a statutory limitation of
three years following the effective date of the final rule (i.e., the
publication date of the final rule) with the possibility of a site-
specific extension of up to one year for the installation of controls
to comply with the final standards, or to allow for waste minimization
reductions.
In the May 1997 NODA, we acknowledged that the April 1996 NPRM
definition of compliance date and our approach to implementation
created a number of unforseen difficulties (see 63 FR at 24236).
Commenters note that the proposed compliance date definition and the
ramifications of noncompliance create the potential for an
unnecessarily large number of source shut-downs due to an insufficient
period to perform all the required tasks. Commenters recommend we
follow the general provisions applicable to all MACT regulated sources,
which allow sources to demonstrate compliance through
[[Page 52909]]
performance testing and submission of emission test results up to 270
days following the compliance date.
In the May 1997 NODA, we outlined an approach that allowed
facilities to use the Part 63 general approach, which requires sources
to complete performance testing within 180 days of the compliance date
and submit test results 90 days after completing the performance
test.178 Today, we adopt this approach to foster consistent
implementation of this rule as a CAA regulation.
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\178\ The general provisions of part 63 allow for 180 days after
the compliance date to conduct a performance test and 60 days to
submit its results to the appropriate regulatory agency. However, as
commenters note, dioxin/furan analyses can require 90 days to
complete. Therefore, the time allowed for submission of test results
should be extended to 90 days, increasing the total time following
the compliance date to 270 days. We agree with commenters and
increase the time allowed for submission of test results from 60 to
90 days.
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Your individual dates for: (1) Compliance; (2) comprehensive
performance testing; (3) submittal of test results; and (4) submittal
of your NOC and title V permit requests depend on whether you were an
existing source on April 19, 1996. Compliance dates for existing and
new sources are discussed in the following two subsections.
B. What Is the Compliance Date for Sources Affected on April 19, 1996?
The compliance date for all affected sources constructed, or
commencing construction or reconstruction before April 19, 1996 is
September 30, 2002.
C. What Is the Compliance Date for Sources That Become Affected After
April 19, 1996?
If you began construction or reconstruction after April 19, 1996,
your compliance date is the latter of September 30, 1999 or the date
you commence operations. If today's final emission standards are less
stringent or as stringent as the standards proposed on April 19, 1996,
you must be in compliance with the 1996 proposed standards upon
startup. If today's final standards are more stringent than the
proposed standards, you must be in compliance with the more stringent
standards by September 30, 2002.
III. What Are the Requirements for the Notification of Intent to
Comply?
For the reader's convenience, we summarize here the Notice of
Intent to Comply (NIC) requirements finalized in the ``fast-track''
rule of June 19, 1998. (See 63 FR at 33782.)
The NIC requires you to prepare an implementation plan that
identifies your intent to comply with the final rule and the basic
means by which you intend to do so. That plan must be released to the
public in a public forum and formally submitted to the Agency. The
notice of intent certifies your intentions--either to comply or not to
comply--and identifies milestone dates that measure your progress
toward compliance with the final emission standards or your progress
toward closure, if you choose not to comply. Prior to submitting the
NIC to the regulatory Agency, you must provide notice of a public
meeting and conduct an informal public meeting with your community to
discuss the draft NIC and your plans for achieving compliance with the
new standards.
We have redesignated the existing NIC provisions to meld them into
the appropriate sections of subpart EEE. We have also revised the
regulatory language to include references to the new provisions
promulgated today. See Part Six, Section IX of today's preamble.
IV. What Are the Requirements for Documentation of Compliance?
A. What Is the Purpose of the Documentation of Compliance?
The purpose of the Documentation of Compliance 179 (DOC)
is for you to certify by the compliance date that: (1) You have made a
good faith effort to establish limits on the operating parameters
specified in Sec. 63.1209 that you believe ensure compliance with the
emissions standards; (2) required continuous monitoring systems are
operational and meet specifications; and (3) you are in compliance with
the other operating requirements. See Sec. 63.1211(d). This is
necessary because all sources must be in compliance by the compliance
date even though they are not required to demonstrate compliance,
through performance testing, until 180 days after the compliance date.
To fulfill the requirements of the DOC, you must place it in the
operating record by the compliance date, September 30, 2002. (See
compliance dates in Section II above.) Information that must be in the
DOC includes all information necessary to determine your compliance
status (e.g., operating parameter limits; functioning automatic waste
feed cutoff system). All operating limits identified in the DOC are
enforceable limits. However, if these limits are determined, after the
initial comprehensive performance test, to have been inadequate to
ensure compliance with the MACT standards, you will not be deemed to be
out of compliance with the MACT emissions standards, if you complied
with the DOC limits.180
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\179\ We renamed the proposed Precertification of Compliance as
the Documentation of Compliance to avoid any confusion with the RCRA
requirement of similar name.
\180\ Once you determine that you failed to demonstrate
compliance during the performance test, all monitoring data is
subject to potential case-by-case use as credible evidence to show
noncompliance following that determination. Therefore, you could
potentially find yourself in noncompliance for the period which the
DOC limits were in effect following that determination, but before
submission of the NOC.
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B. What Is the Rationale for the DOC?
In the May 1997 NODA, we discussed the concept of the
precertification of compliance (Pre-COC). The discussion required
sources to precertify their compliance status on the compliance date by
requiring them to submit a notification to the appropriate regulatory
agency. This notification would detail the operating limits under which
a source would operate during the period following the compliance date,
but before submittal of the initial comprehensive performance test
results in the Notification of Compliance.
Commenters question this provision since the Pre-COC operating
limits would be effective only for the 270 days following the
compliance date. Other commenters support the Pre-COC requirements
provided the process is focused, straightforward, and limited to the
minimum operating parameters necessary to document compliance.
Commenters also stress that the Agency needed to specify the
requirements of the prenotification, using appropriate sections of 40
CFR 266.103(b) and Section 63.9 when developing the specific regulatory
requirements. In addition, commenters suggest that the Agency clarify
the relationship between the Pre-COC and the title V permit, and
indicate how or if the Pre-COC operating limits would be placed in the
title V permit.
Other commenters state that the rationale underlying the Pre-COC is
faulty because sources would remain subject to the RCRA permit
conditions until the NOC is submitted or until the title V permit is
issued, which was our proposed approach to permitting at that time.
Therefore, the Agency's concern that sources could be between
regulatory regimes is not relevant. Commenters also state that Pre-COC
requirements would be resource intensive and a needless exercise that
diverted time and attention from preparing to come into compliance with
MACT standards.
The DOC requirements and process adopted today provide the Agency
and public a sound measure of assurance
[[Page 52910]]
that, on the compliance date, combustion sources are operated within
limits that should ensure compliance with the MACT standards and
protection to human health and the environment. We agree that operating
limits in the DOC will be in effect only for a short period of time and
that affected sources will not be between regulatory regimes at any
time. Given the relatively short period of time the DOC conditions will
be in effect, however, we chose for the final rule not to specify
whether the conditions need to be incorporated into a title V permit
and do not require the permitting authority to do so. We provide
flexibility for agencies implementing title V programs to determine the
appropriate level of detail to include in the permit, thereby allowing
them to minimize the potential need for permit revisions. In addition,
we do not require that the DOC be submitted to the permitting
authority, to avoid burdening the permitting agency with unnecessary
paper work during the period that they are reviewing site-specific
performance test plans. In today's rule, we better define the period
during which the DOC applies by specifying that the DOC is superseded
by the NOC upon the postmark date for submittal of the NOC. Once you
mail the NOC, its contents become enforceable unless and until
superseded by test results submitted within 270 days following
subsequent performance testing. This approach provides clarity on when
the NOC supersedes the DOC.
C. What Must Be in the DOC?
You must complete your site-specific DOC and place it in your
operating record by the compliance date. The DOC must contain all of
the information necessary to determine your compliance status during
periods of operation including all operating parameter limits. You must
identify the DOC operating limits through the use of available data and
information. If your unit requires modification or upgrades to achieve
compliance with the emission standards, you can base this judgment on
results of shakedown tests and/or manufacturers assertions or
specifications. If your unit does not require modifications or upgrades
to meet the emission standards of today's rule, you can develop the
operating limits through analysis of previous performance tests or
knowledge of the performance capabilities of your control equipment.
Your limitations on operating parameters must be based on an
engineering evaluation prepared under your direction or supervision in
accordance with a system designed. This evaluation must ensure that
qualified personnel properly gathered and evaluated the information and
supporting documentation, and considering at a minimum the design,
operation, and maintenance characteristics of the combustor and
emissions control equipment, the types, quantities, and characteristics
of feedstreams, and available emissions data.
This requirement should not involve a significant effort because
your decisions on whether to upgrade and modify your units will be
based on the current performance of your control equipment and the
performance capabilities of new equipment you purchase. We expect that,
by the compliance date, you will have an adequate understanding of your
unit's capabilities, given the three years to develop this expertise.
Therefore, by the compliance date, you are expected to identify
operating limits that are based on technical or engineering judgment
that should ensure compliance with the emission standards.
V. What Are the Requirements for MACT Performance Testing?
A. What Are the Compliance Testing Requirements?
Today's final rule requires two types of performance testing to
demonstrate compliance with the MACT emission standards: Comprehensive
and confirmatory performance testing. See Sec. 63.1207. The purpose of
comprehensive performance testing is to demonstrate compliance and
establish operating parameter limits. You must conduct your initial
comprehensive performance tests by 180 days (i.e., approximately six
months) after your compliance date. You must submit results within 90
days (i.e., approximately 3 months) of completing your comprehensive
performance test. If you fail a comprehensive performance test, you
must stop burning hazardous waste until you can demonstrate compliance
with today's MACT standards. Comprehensive performance testing must be
repeated at least every five years, but may be required more frequently
if you change operations or fail a confirmatory performance test.
The purpose of confirmatory performance tests is to confirm
compliance with the dioxin/furan emission standard during normal
operations. You must conduct confirmatory performance tests midway
between comprehensive performance tests. Confirmatory performance tests
may be conducted under normal operating conditions. If you fail a
confirmatory performance test, you must stop burning hazardous waste
until you demonstrate compliance with the dioxin/furan standard by
conducting a comprehensive performance test to establish revised
operating parameter limits.
The specific requirements and procedures for these two performance
tests are discussed later in this section. In addition, this section
discusses the interaction between the RCRA permitting process and the
MACT performance test.
1. What Are the Testing and Notification of Compliance Schedules?
Section 63.7 of the CAA regulations contains the general
requirements for testing and notification of compliance. In today's
rule, we adopt some Sec. 63.7 requirements without change and adopt
others with modifications. As summarized earlier, you must commence
your initial comprehensive performance test within 180 days after your
compliance date, consistent with the general Sec. 63.7 requirements.
You must complete testing within 60 days of commencement, unless a time
extension is granted. This requirement is necessary because testing and
notification of compliance deadlines are based on the date of
commencement or completion of testing. Those deadlines could be
meaningless if a source had unlimited time to complete testing.
Although we propose to require testing to be completed within 30 days
of commencement, commenters state that unforeseen events could occur
(e.g., system breakdown causing extensive repairs; loss of samples from
breakage of equipment or other causes requiring additional test runs)
that could extend the testing period beyond normal time frames. We
concur, and provide for a 60-day test period as well as a case-by-case
time extension that may be granted by permit officials if warranted
because of problems beyond our control.
Additionally, you must submit comprehensive performance test
results to the Administrator within 90 days of test completion, unless
a time extension is granted. We are allowing an additional 30 days for
result submittal beyond the Secs. 63.7(g) and 63.8(e)(5) 60-day
deadlines because the dioxin/furan analyses required in today's rule
may take this additional time to complete. We also are including a
provision for a case-by-case time extension in the final rule because
commenters express concern that the limited laboratory facilities
nationwide may be taxed by the need to handle analyses simultaneously
for many hazardous
[[Page 52911]]
waste combustors. The available analytical services may not be able to
handle the workload, that could cause some sources to miss the proposed
90-day deadline. We concur with commenters' concerns and have added a
provision to allow permit officials to grant a case-by-case time
extension, if warranted.
Test results must be submitted as part of the notification of
compliance (NOC) submitted to the Administrator under Secs. 63.1207(j)
and 63.1210(d) documenting compliance with the emission standards and
continuous monitoring system requirements, and identifying applicable
operating parameter limits. These provisions are similar to
Secs. 63.7(g) and 63.8(e)(5), except that the NOC must be postmarked by
the 90th day following the completion of performance testing and the
continuous monitoring system performance evaluation.
Overall, the initial NOC must be postmarked within 270 days (i.e.,
approximately nine months) after your compliance date. You must
initiate subsequent comprehensive performance tests within 60 months
(i.e., five years) of initiating your initial comprehensive performance
test. You must submit subsequent NOCs, containing test results, within
90 days after the completion of subsequent tests.
The rule allows you to initiate subsequent tests any time up to 30
days after the deadline for the subsequent performance test. Thus, you
can modify the combustor or add new emission control equipment at any
time and conduct new performance testing to document compliance with
the emission standards. In addition, this testing window allows you to
plan to commence testing well in advance of the deadline to address
unforseen events that could delay testing.181 This testing
window applies to both comprehensive performance tests and confirmatory
performance tests. For example, if the deadline for your second
comprehensive performance test is January 10, 2008, you may commence
the test at any time after completing the initial comprehensive
performance test but not later than February 10, 2008. The deadline for
subsequent comprehensive and confirmatory performance tests are based
on the commencement date of the previous comprehensive performance
test.
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\181\ We note that a case-by-case time extension for
commencement of subsequent performance testing is also provided
under Sec. 63.1207(i).
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2. What Are the Procedures for Review and Approval of Test Plans and
Requirements for Notification of Testing?
In the April 1996 NPRM, we proposed in Sec. 63.7(b)(1) to require
submittal of a ``notification of performance test'' to the
Administrator 60 days prior to the planned test date. This notification
included the site-specific test plan itself for review and approval by
the Administrator (Sec. 63.8(e)(3)). In the May 1997 NODA, to ensure
coordination of destruction removal efficiency (DRE) and MACT
performance testing, we considered requiring you to submit the test
plan one year rather than 60 days prior to the scheduled test date to
allow the regulatory official additional time to consider DRE testing
in context with MACT comprehensive performance testing. This one-year
test review period would only have applied to sources required to
perform a DRE test.
In today's final rule, we maintain the requirement for you to
submit the test plan one year prior to the scheduled test date, but
apply that requirement to all sources, not just those performing a DRE
test. After consideration of comments (described below), we determined
that this one-year period is needed to provide regulatory officials
sufficient time (i.e., nine months) to review and approve or notify you
of intent to disapprove the plan. Nine months is needed for the review
for all sources given the amount of technical information that would be
included in the test plan, and would also allow time to assess whether
a source is required to perform a DRE test (see Part IV, Section IV,
for discussion of DRE testing requirements; see also
Sec. 63.1206(b)(8)). During this nine-month period, the regulatory
officials will review your test plan and determine if it is adequate to
demonstrate compliance with the emission standards and establish
operating requirements.
After submittal of the test plan, review and approval or
notification of intent to deny approval of the test plan will follow
the requirements of Sec. 63.7(c)(3). That section provides procedures
for you to provide additional information before final action on the
plan. It also requires you to comply with the testing schedule even if
permit officials have not approved your test plan. The only exception
to this requirement is if you proposed to use alternative test methods
to those specified in the rule. In that case, you may not conduct the
performance test until the test plan is approved, and you have 60 days
after approval to conduct the test.
Several commenters suggest that it would be difficult for permit
officials to review and approve test plans within the nine-month window
given that many test plans may be submitted at about the same time.
They cite experiences under RCRA trial burn plan approvals where permit
officials have taken much longer than nine months to approve a plan,
and have requested that the final rule allow for a longer review
period. Commenters are concerned with the consequences of being
required to conduct the performance test even though permit officials
may not have had time to approve the test plan. They recite various
concerns that permit officials may at a later date determine that the
performance test was inadequate and require retesting. Commenters
suggest that the rule establish the date for the initial comprehensive
performance test as 60 days following approval of the test plan,
whenever that may occur, thus extending the deadline for the
performance test indefinitely from the current requirement of six
months after the compliance date.
We maintain that the nine-month review period is appropriate for
several reasons. First, we are unwilling to build into the regulations
an indefinite period for review. This would have the potential to delay
implementation of the MACT emission standards without any clear and
compelling reason to do so.
Second, the RCRA experience with protracted approval schedules,
sometimes over a decade ago, is not applicable or analogous to the MACT
situation. Under the RCRA regulatory regime, particularly at the early
stages, there were few incentives for either permit officials or owners
or operators to expeditiously negotiate acceptable test plans. No
statutory deadlines existed for a compliance date, and existing
facilities operated under interim status (a type of grand fathering
tantamount to a permit). This interim status scheme placed at least
some controls on hazardous waste combustors during the permit
application and trial burn test plan review periods. As a result,
regulatory officials could take significant amounts of time to address
what was then a new type of approval, that for trial burn testing to
meet RCRA final permit standards.
Under MACT, the situation today is quite different. In light of the
statutory compliance date of 3 years and the existing regulatory
framework, sources know as of today's final rule that they need to
respond promptly and effectively to permit officials' concerns about
the test plan because the performance test must be conducted
[[Page 52912]]
within six months after the compliance date whether or not the test
plan is approved. And they have at least two years to prepare and
submit these plans, and to work with regulatory officials even before
doing so. For their part, permit officials recognize that they have the
responsibility to review and approve the plan or notify the source of
their intent to deny approval within the nine-month window given that
the source must proceed with expensive testing on a fixed deadline
whether or not the plan is approved. To the extent regulatory officials
anticipate that many test plans will be submitted at about the same
time, the agencies have at least two years to figure out ways to
accommodate this scenario from a resource and a prioritization
standpoint. If permit officials nevertheless fail to act within the
nine-month review and approval period, a source could argue that this
failure is tacit approval of the plan and that later ``second-
guessing'' is not allowable. This should be a very strong incentive for
regulatory officials to act within the nine months, especially with a
two-year lead time to avoid this type of situation
In addition, the RCRA experience is not a particularly good
harbinger of the future MACT test plan approval, as commenters suggest,
because most sources will have already completed trial burn testing
under RCRA. Thus, both the regulatory agencies and the facilities have
been through one round of test plan submittal, review, and approval for
their combustion units. Given that MACT testing is very similar to RCRA
testing, approved RCRA test protocols can likely be modified as
necessary to accommodate any changes required under the MACT rule.
Although some of these changes may be significant, we expect that many
will not be. For example, RCRA trial burn testing always included DRE
testing. Under the MACT rule, DRE testing will not be required for most
sources. And for sources where DRE testing is required under MACT, most
will have already been through a RCRA approval of the DRE test
protocol, which should substantially simplify the process under MACT.
The third reason that we maintain the nine-month review and
approval window is appropriate is that discussions with several states
leads us to conclude that they are prepared to meet their obligations
under this provision. This is a highly significant indicator that the
nine-month review and approval period is a reasonable period of time,
particularly since all permitting agencies have at least two years to
plan for submittal of test plans from the existing facilities in their
jurisdictions.
In summary, sound reasons exist to expect that today's final rule
provides sufficient time for the submittal, review, and approval of
test plans. Furthermore, clear incentives exist for both owners and
operators and permit officials to work together expeditiously to ensure
that an approval or notice of intent to disapprove the test plan can be
provided within the nine-months allotted.
On a separate issue, we also retain, in today's final rule, the 60-
day time frame and requirements of Sec. 63.7(b)(1) for submittal of the
notification of performance test. Additionally, the final rule
continues to provide an opportunity for, but does not require, the
regulatory agency to review and oversee testing.
3. What Is the Provision for Time Extensions for Subsequent Performance
Tests?
The Administrator may grant up to a one year time extension for any
performance test subsequent to the initial comprehensive performance
test. This enables you to consolidate MACT performance testing and any
other emission testing required for issuance or reissuance of Federal/
State permits.182
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\182\ In addition, this provision also may assist you when
unforseen events beyond your control (e.g., power outage, natural
disaster) prevent you from meeting the testing deadline.
---------------------------------------------------------------------------
At the time of proposal, we were concerned about how to allow
coordination of MACT performance tests and RCRA trial burns. As
discussed elsewhere, the RCRA trial burn is superseded by MACT
performance testing. However, a one-year time extension may still be
necessary for you to coordinate performance of a RCRA risk burn. In
addition, commenters state that there may be additional reasons to
grant extension requests (e.g. some TSCA-regulated hazardous waste
combustors may be required to perform stack tests beyond those required
by MACT). Furthermore, some sources may have to comply with state
programs requiring RCRA trial burn testing. To address these
situations, to promote coordinated testing, and to avoid unnecessary
source costs, the final rule allows up to a one-year time extension for
the performance test.
When performance tests and other emission tests are consolidated,
the deadline dates for subsequent comprehensive performance tests are
adjusted correspondingly. For example, if the deadline for your
confirmatory performance test is January 1 and your state-required
trial burn is scheduled for September 1 of the same year, you can apply
to adjust the deadline for the confirmatory performance test to
September 1. If granted, this also would delay by a corresponding time
period the deadline dates for subsequent comprehensive performance
tests.
The procedures for granting or denying a time extension for
subsequent performance tests are the same as those found in
Sec. 63.6(i), which allow the Administrator to grant sources up to one
additional year to comply with standards.183 These are also
the same procedures apply to a request for a time extension for the
initial NOC.
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\183\ Note, however, that Sec. 63.6(i) applies to an entirely
different situation: extension of time for initial compliance with
the standards, not subsequent performance testing.
---------------------------------------------------------------------------
4. What Are the Provisions for Waiving Operating Parameter Limits
During Subsequent Performance Tests?
Operating parameter limits are automatically waived during
subsequent comprehensive performance tests under an approved
performance test plan. See Sec. 63.1207(h). This waiver applies only
for the duration of the comprehensive performance test and during
pretesting for an aggregate period up to 720 hours of operation. You
are still required to be in compliance with MACT emissions standards at
all times during these tests, however.
In the April 1996 NPRM, we proposed to allow the burning of
hazardous waste only under the operating limits established during the
previous comprehensive performance test (to ensure compliance with
emission standards not monitored with a continuous emissions monitoring
system). Two types of waivers from this requirement would have been
provided during subsequent comprehensive performance tests: (1) An
automatic waiver to exceed current operating limits up to 5 percent;
and (2) a waiver that the Administrator may grant if warranted to allow
the source to exceed the current operating limits without restriction.
We proposed an automatic waiver because, without the waiver, the
operating limits would become more and more stringent with subsequent
comprehensive performance tests. This is because sources would be
required to operate within the more stringent conditions to ensure that
they did not exceed a current operating limit. This would result in a
shrinking operating envelope over time.
A number of commenters question the comprehensive performance
test's 5%
[[Page 52913]]
limit over existing permit conditions. Some commenters state that the
EPA should not limit a facility's operating envelope from test to test
based on operating conditions established during the previous test. The
operator should be free to set any conditions for the comprehensive
performance test, short of what the regulator deems to pose a short-
term environmental or health threat or inadequate to ensure compliance
with an emission standard. Commenters also state that the requirement
that the facility accept the more stringent of the existing 5% limit or
the test result will inevitably result in the ratcheting down of limits
over time. Since certain conditions have much greater variation than 5%
over a limit, sufficient variability must be allowed so the operator
can run a test under the conditions it wishes to use as the basis for
worst case operation.
We agree that a waiver is necessary to avoid ratcheting down the
operating limits in subsequent tests. Further, in view of the natural
variability in hazardous waste combustor operations, a 5% waiver may be
insufficient. Because you are required to comply with the emission
standards, there does not appear to be any reason to establish national
restrictions on operations during subsequent performance tests.
Therefore, the final rule allows a waiver from previously established
operating parameter limits, as long as you comply with MACT emission
standards and are operating under an approved comprehensive performance
test plan. Operating parameter limits will be reset based on the new
tests. Furthermore, the permitting authority will review and has the
opportunity to disapprove any proposed test conditions which may result
in an exceedance of an emission standard.
B. What Is the Purpose of Comprehensive Performance Testing?
The purposes of the comprehensive performance test are to: (1)
Demonstrate compliance with the continuous emissions monitoring
systems-monitored emission standards for carbon monoxide and
hydrocarbons; (2) conduct manual stack sampling to demonstrate
compliance with the emission standards for pollutants that are not
monitored with a continuous emissions monitoring system (e.g., dioxin/
furan, particulate matter, DRE, mercury, semivolatile metal, low
volatile metal, hydrochloric acid/chlorine gas); (3) establish limits
on the operating parameters required by Sec. 63.1209 (Monitoring
Requirements) to ensure compliance is maintained with those emission
standards for which a continuous emissions monitoring system is not
used for compliance monitoring; and (4) demonstrate that performance of
each continuous monitoring system is consistent with applicable
requirements and the quality assurance plan. In general, the
comprehensive performance test is similar in purpose to the RCRA trial
burn and BIF interim status compliance test, but with relatively less
Agency oversight and a higher degree of self-implementation, as
discussed below.
The basic framework for comprehensive performance testing is set
forth in the existing general requirements of subpart A, part 63.
Therefore, for convenience of the reader, we will review key elements
of those regulations and highlight any modifications made specifically
for hazardous waste combustors.
1. What Is the Rationale for the Five Year Testing Frequency?
As discussed earlier, you must perform comprehensive performance
testing every five years. We require periodic comprehensive performance
testing because we are concerned that long-term stress to the critical
components of a source (e.g., firing systems, emission control
equipment) could adversely affect emissions.
In the April 1996 NPRM, we proposed that large sources (i.e., those
with a stack gas flow rate greater than 23,127 acfm) and sources that
accept off-site wastes would be required to perform comprehensive
performance testing every three years. We also proposed that small, on-
site sources perform comprehensive performance testing every five years
unless the Administrator determined otherwise on a case-specific basis.
Commenters suggest that the proposed three year testing frequency is
too restrictive. They said that test plan approval time, bad weather,
mechanical failure, and the testing itself combine to make the proposed
test frequency too tight for tests of this magnitude.
We agree that, due to the magnitude of the comprehensive
performance test, a more appropriate testing schedule is required.
Therefore, we adopt a comprehensive performance testing frequency of
every five years for small and large sources. In addition, this
comprehensive performance testing schedule should correspond to the
renewal of the title V permit. More frequent comprehensive performance
testing is required, however, if there is a change in design,
operation, or maintenance that may adversely affect compliance. See
Sec. 63.1206(b)(6).
2. What Operations Are Allowed During a Comprehensive Performance Test?
Because day-to-day limits are established for operating parameters
during the comprehensive performance test, we allow operation during
the performance test as necessary provided the unit complies with the
emission standards. Accordingly, you can spike feedstreams with metals
or chlorine, for example, to ensure that the feedrate limits are
sufficient to accommodate normal operations while allowing some
flexibility to feed higher rates. See Part Four, Section I. B. above
for further discussion of normal operations. We note that this differs
from Sec. 63.7(e) which requires performance testing under ``normal''
operating conditions. See Sec. 63.1207(g).
Most commenters agree that the comprehensive performance test
should be conducted under extreme conditions at the edge of the
operating envelope. Commenters point out that they needed to operate in
this mode to establish operating parameter limits to cover all possible
normal operating emissions values. Commenters also state that
feedstreams may need to be spiked with metals or chlorine to ensure
limits high enough to allow operational flexibility. We agree that
these modes of operation are needed to establish operating parameter
limits that cover all possible normal operating emissions
values.184 There is precedent for this approach in current
rules regulating hazardous waste combustors (e.g., the RCRA incinerator
and BIF rules).
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\184\ Allowing sources to operate during MACT comprehensive
performance testing under the worst-case conditions, as allowed
during RCRA compliance testing, rather than under normal conditions
as provided by Sec. 63.7(e) for other MACT sources, ensures that the
emissions standards do not restrict hazardous waste combustors using
MACT control to operations resulting in emissions that are lower
than normal. Therefore, allowing performance testing on a worst-case
basis provides that the MACT emission standards are achievable in
practice by sources using MACT control.
---------------------------------------------------------------------------
In addition, two or more modes of operation may be identified, for
which separate performance tests must be conducted and separate limits
on operating conditions must be established. If you identify two modes
of operation for your source, you must note in the operating record
which mode you are operating under at all times. For example, two modes
of operation must be identified for a cement kiln that routes kiln off-
gas through the raw meal mill to help dry the raw meal. When the raw
meal mill is not operating (perhaps 15% of the time), the kiln gas
bypasses the raw meal mill. Emissions of particulate matter and other
hazardous air
[[Page 52914]]
pollutants or surrogates may vary substantially depending on whether
the kiln gas bypasses the raw meal mill.
As discussed below for confirmatory testing, when conducting the
comprehensive performance test, you also must operate under
representative conditions for specified parameters that may affect
dioxin/furan emissions. These conditions must ensure that emissions are
representative of normal operating conditions. Also, when demonstrating
compliance with the particulate matter, semivolatile metal, and low
volatile metal emission standards, when using manual stack sampling,
and when demonstrating compliance with the dioxin/furan and mercury
emission standards using carbon injection or carbon bed, you must
operate under representative conditions for the cleaning cycle of the
particulate matter control device. This is because particulate matter
emissions increase momentarily during cleaning cycles and can affect
emissions of these pollutants.
3. What Is the Consequence of Failing a Comprehensive Performance Test?
If you determine that you failed any emission standard during the
performance test based on: (1) Continuous emissions monitoring systems
recordings; (2) results of analysis of samples taken during manual
stack sampling; or (3) results of the continuous emissions monitoring
systems performance evaluation, you must immediately stop burning
hazardous waste. However, if you conduct the comprehensive performance
test under two or more modes of operation, and you meet the emission
standards when operating under one or more modes of operation, you are
allowed to continue burning under the mode of operation for which the
standards were met.
If you fail one or more emission standards during all modes of
operation tested, you may burn hazardous waste only for a total of 720
hours and only for the purposes of pretesting (i.e., informal testing
to determine if the combustor can meet the standards operating under
modified conditions) or comprehensive performance testing under
modified conditions. The same standards apply for the retest as applied
for the original test. These conditions apply when you fail the initial
or subsequent comprehensive performance test.
A number of commenters suggest that the 720 operating hours allowed
after a failed performance test should be renewable, as they are under
existing incinerator and BIF rules. We are persuaded by the commenters'
rationale and will adopt this practice in today's rule. The final rule
allows the 720 hours of operation following a failed performance test
to be renewed as often as the Administrator deems reasonable. We note
that hazardous waste combustors are currently subject to virtually
these same requirements under RCRA rules.
If you fail a comprehensive performance test, you must still submit
a NOC as required indicating the failure. We want to ensure that the
regulatory authorities are fully aware of a failure and the need for
the facility to initiate retesting.
We do not specifically address other consequences of failing the
comprehensive performance test in the regulatory language. We will
instead rely on the regulating agency's enforcement policy to govern
the type of enforcement response at a facility that exceeds an emission
standard, fails to ensure compliance with the standards, or fails to
meet a compliance deadline.
C. What Is the Rationale for Confirmatory Performance Testing?
Confirmatory performance testing for dioxin/furan is required
midway between the cycle required for comprehensive performance testing
to ensure continued compliance with the emission standard. We require
such testing only for dioxin/furan given: (1) The health risks
potentially posed by dioxin/furan emissions; (2) the lack of a
continuous emissions monitoring system for dioxin/furan; (3) the lack
of a material that directly and unambiguously relates to dioxin/furan
emissions which could be monitored continuously by means of feedrate
control (as opposed to, for example, metals feedrates, which directly
relate to metals emissions); and (4) wear and tear on the equipment,
including any emission control equipment, which over time could result
in an increase in dioxin/furan emissions even though the source stays
in compliance with applicable operating limits.
Although emissions of dioxins/furans appear to be primarily a
function of whether particulate matter is retained in post-combustion
regions of the combustor (e.g., in an electrostatic precipitator or
fabric filter, or on boiler tubes) in the temperature range that
enhances dioxin/furan formation, the factors that affect dioxin/furan
formation are imperfectly understood. Certain materials seem to inhibit
formation while others seem to enhance formation. Some materials seem
to be precursors (e.g., PCBs). Changes in the residence time of
particulate matter in a control device may affect the degree of
chlorination of dioxins/furans, and thus the toxicity equivalents of
the dioxins/furans. Given these uncertainties, the health risks posed
by dioxins/furans, and the relatively low cost of dioxin/furan testing,
it appears prudent to require confirmatory testing to determine if
changes in feedstocks or operations that are not limited by the MACT
rule may have increased dioxin/furan emissions to levels exceeding the
standard. We also note that confirmatory dioxin/furan testing is
required for municipal waste combustors (60 FR at 65402 (December 19,
1995)).
Confirmatory testing differs from comprehensive testing, however,
in that you are required to operate under normal, representative
conditions during confirmatory testing. This will reduce the cost of
the test, while providing the essential information, because you will
not have to establish new operating limits based on the confirmatory
test.
1. Do the Comprehensive Testing Requirements Apply to Confirmatory
Testing?
The following comprehensive performance testing requirements
discussed above also apply to confirmatory testing: Agency oversight,
notification of performance test, notification of compliance, time
extensions, and failure to submit a timely notice of compliance.
However, we modify some of the comprehensive test requirement for
confirmatory tests, as discussed below.
2. What Is the Testing Frequency for Confirmatory Testing?
You are required to conduct confirmatory performance testing 30
months (i.e., 2.5 years) after the previous comprehensive performance
test. The same two-month testing window, applicable for comprehensive
tests, also applies to confirmatory tests.
Several commenters state that the proposed schedule for
confirmatory tests is too frequent. The April 1996 NPRM would have
required large and off-site sources to conduct confirmatory performance
testing 18 months after the previous comprehensive performance test.
Small, on-site sources would have been required to conduct the testing
30 months after the previous comprehensive performance test. One
commenter suggests that the frequency should be at multiples of 12
months to avoid seasonal weather problems in many locations. Other
commenters state that EPA's justification for confirmatory tests is not
supported by evidence
[[Page 52915]]
showing increased emissions due to equipment aging and that the
performance of combustion practice parameters is already assured
through continuous monitoring systems.
We agree that due to the magnitude and expense of the test, a more
appropriate testing schedule would be every 2.5 years, mid-way between
the comprehensive performance test cycle. In addition, we agree that
testing in certain locations at certain times of the year (e.g.,
northern states in the winter) can be undesirable. Although possible,
it would add to the difficulty and expense of the testing. As
previously discussed, sources can request a time extension to allow for
a more appropriate testing season. However, the regulatory date for
confirmatory testing remains midcycle to the comprehensive performance
testing.
3. What Operations Are Allowed During Confirmatory Performance Testing?
As proposed, you are required to operate under normal conditions
during confirmatory performance testing. Normal operating conditions
are defined as operations during which: (1) The continuous emissions
monitoring systems that measure parameters that could relate to dioxin/
furan emissions--carbon monoxide or hydrocarbons--are recording
emission levels within the range of the average value for each
continuous emissions monitoring system (the sum of all one-minute
averages, divided by the number of one minute averages) over the
previous 12 months to the maximum allowed; (2) each operating parameter
limit established to maintain compliance with the dioxin/furan emission
standard (see discussion in Part Five, Section VI.D.1 below and
Sec. 63.1209(k)) is held within the range of the average values over
the previous 12 months and the maximum or minimums, as appropriate,
that are allowed; (3) chlorine feedrates are set at normal or greater;
and (4) when using carbon injection or carbon bed, the test is
conducted under representative conditions for the cleaning cycle of the
particulate matter control device. See Sec. 63.1207(g)(2).
We define normal operating conditions in this manner because,
otherwise, sources could elect to limit levels of the regulated dioxin/
furan operating parameters (e.g., hazardous waste feedrate, combustion
chamber temperature, temperature at the inlet to the dry particulate
matter control device) to ensure minimum emissions. Thus, without
specifying what constitutes normal conditions, the confirmatory test
could be meaningless. On the other hand, the definition of normal
conditions is broad enough to allow adequate flexibility in operations
during the test. The confirmatory test confirms that your under day-to-
day operations are meeting the dioxin/furan standard. Thus, the
confirmatory test differs from the comprehensive performance test in
which you may choose to extend to the edge of the operating envelope to
establish operating parameters.
The April 1996 NPRM would have required normal operating conditions
for particulate matter continuous emissions monitoring systems. For the
final rule, particulate matter levels are limited during confirmatory
testing to ensure normal operations only when your source is equipped
with carbon injection or carbon bed for dioxin/furan emissions control
(see dioxin/furan operating limits discussion below).
The April 1996 NPRM also would have required you to operate under
representative conditions for types of organic compounds in the waste
(e.g., aromatics, aliphatics, nitrogen content, halogen/carbon ratio,
oxygen/carbon ratio) and volatility of wastes when demonstrating
compliance with the dioxin/furan emission standard. Several commenters
object to this requirement. We agree that restrictions on these organic
compounds in the waste are redundant and not necessary to assure good
combustion. In addition, the requirement would be impracticable because
in most cases measured data would not be available on these parameters.
Therefore, the final rule does not require ``representative'' wastes
with regard to these organic compounds for confirmatory testing.
It is prudent to require that chlorine be fed at normal levels or
greater during the dioxin/furan confirmatory performance test. Although
most studies show poor statistical correlation between dioxin/furan
emissions and chlorine feedrate, some practical considerations are
important. Chlorinated dioxin/furan obviously contain chlorine and some
level of chlorine is necessary for its formation. During the
confirmatory testing for dioxin/furan, we want you to operate your
combustor under normal conditions relative to factors that can affect
emissions of dioxin/furan. Therefore, you must feed chlorine at normal
or greater levels given the potential for chlorine feedrates to affect
dioxin/furan emissions. For the confirmatory performance test, normal
is defined as the average chlorine fed over the previous 12 months. If
you have established a maximum chlorine value for metals or total
chlorine compliance in your previous comprehensive performance test,
then that value can be used in the confirmatory test.
Several commenters suggest that when defining normal operation, a
provision should be made to exclude inappropriate data, such as those
occurring during instrument malfunction, at unit down time, or during
instrument zero/calibration adjustment. The April 1996 NPRM did not
allow for any data to be excluded. To define ``normal'' operation, we
agree it is reasonable to exclude inappropriate data. For the final
rule, calibration data, malfunction data, and data obtained when not
burning hazardous waste do not fall into the definition of ``normal''
operation.
4. What Are the Consequences of Failing a Confirmatory Performance
Test?
If you determine that you failed the dioxin/furan emission standard
based on results of analysis of samples taken during manual stack
sampling, you must immediately stop burning hazardous waste. You must
then modify the design or operation of the unit, conduct a new
comprehensive performance test to demonstrate compliance with the
dioxin/furan emission standard (and other standards if the changes
could adversely affect compliance with those standards), and establish
new operating parameter limits. Further, prior to submitting a NOC
based on the new comprehensive performance test, you can burn hazardous
waste only for a total of 720 hours (renewable based on the discretion
of the Administrator) and only for purposes of pretesting or
comprehensive performance testing. These conditions apply when you fail
the initial or any periodic confirmatory performance test.
However, if you conduct the comprehensive performance test under
two or more modes of operation, and meet the dioxin/furan emission
standards during confirmatory testing when operating under one or more
modes of operation, you may continue burning under the modes of
operation for which you meet the standards.
Other than stopping burning of hazardous waste, we do not
specifically address the consequences of failing the confirmatory
performance test in the regulatory language but will instead rely on
the regulating agency's enforcement policy to govern the type of
enforcement response at a facility that exceeds an emission standard,
fails to ensure compliance with the standards, or fails to meet a
compliance deadline. This approach is consistent with the way
[[Page 52916]]
other MACT standards are implemented.
Some commenters suggest that the requirement to stop burning waste
after a failed confirmatory test is overly harsh. They suggest that
temporarily restricted burning should be allowed, conservative enough
to insure compliance, while a permanent solution is developed. We
continue to believe that a source should stop burning hazardous waste
until it reestablishes operating parameter limits that ensure
compliance with the dioxin/furan emission standard. We note that
hazardous waste combustors are currently subject to virtually these
same requirements under RCRA rules.
D. What Is the Relationship Between the Risk Burn and Comprehensive
Performance Test?
1. Is Coordinated Testing Allowed?
Traditionally, a RCRA trial burn serves three primary functions:
(1) Demonstration of compliance with performance standards such as
destruction and removal efficiency; (2) determination of operating
conditions that assure the hazardous waste combustor can meet
applicable performance standards; and (3) collection of emissions data
for incorporation into a SSRA that, subsequently, is used to establish
risk-based permit conditions where necessary.185 Today's
rulemaking transfers the first two functions of a RCRA trial burn from
the RCRA program to the CAA program. The responsibility for collecting
emissions data needed to perform a SSRA is not transferred because
SSRAs are exclusively a RCRA matter.
---------------------------------------------------------------------------
\185\ Under 40 CFR 270.10(k), which is the RCRA Part B
information requirement that supports implementation of the RCRA
omnibus permitting authority, a regulatory authority may require a
RCRA permittee or an applicant to submit information to establish
permit conditions as necessary to protect human health and the
environment. Under this authority, risk burns and SSRAs may be
required.
---------------------------------------------------------------------------
Generally speaking, the type of emissions data needed to conduct a
SSRA includes concentration and gas flow rate data for dioxin/furans,
nondioxin/furan organics, metals, hydrogen chloride, and chlorine gas.
Additionally, particle-size distribution data are normally needed for
the air modeling component of the SSRA. We have recently published
guidance on risk burns and the data to be collected. See USEPA, ``Human
Health Risk Assessment Protocol for Hazardous Waste Combustion
Facilities'' External Peer Review Draft, EPA-530-D-98-001A, B & C and
USEPA, ``Guidance on Collection of Emissions Data to Support Site-
Specific Risk Assessments at Hazardous Waste Combustion Facilities,''
EPA 530-D-98-002, August 1998.
A large number of hazardous waste combustors subject to today's
rule will have completed a RCRA trial burn and SSRA emissions testing
prior to the date of the MACT comprehensive performance test. There may
exist, however, some facilities for which this is not the case. For
these facilities, the Agency proposed, in both the April 1996 NPRM and
the May 1997 NODA, an option of coordinating SSRA emissions data
collection with MACT performance testing. Facilities choosing to
perform coordinated testing would be expected to factor SSRA data
collection requirements into the MACT performance test plan. Commenters
support this approach, emphasizing that coordinated testing would
conserve the resources of both the regulatory authority and regulated
source. The Agency agrees with the commenters and continues to support
coordinated testing. There is no need, however, for today's final rule
to include regulatory language for coordinated testing since it is
simply matter of submitting and implementing a test plan which
accomplishes the objectives of both a risk burn and MACT performance
test.
Coordinated testing may not be possible for all hazardous waste
combustors subject to today's MACT standards. Some sources may not be
able to test under one set of conditions that addresses all data needs
for both MACT implementation and SSRAs. SSRA emissions testing
traditionally is performed under worst-case conditions, but may be
obtained under normal testing conditions when necessary.186
As noted in the April 1996 NPRM, as well as in this preamble, we
generally anticipate sources will conduct MACT performance testing
under conditions that are at the edge of the operating envelope or the
worst-case to ensure operating flexibility. Regardless of which test
conditions are used to collect SSRA emissions data, under the
coordinated testing scenario, those conditions should be consistent
with the MACT performance test to the extent possible.
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\186\ Criteria for determining the circumstances under which
SSRA emissions data should be collected using normal versus worst-
case testing conditions are provided in EPA's Guidance on Collection
of Emissions Data to Support Site-Specific Risk Assessments at
Hazardous Waste Combustion Facilities (EPA 530-D-98-002, August
1998).
---------------------------------------------------------------------------
Similarly, a source may experience difficulty integrating MACT
performance testing with SSRA emissions testing due to conflicting
goals in establishing enforceable operating parameters, i.e., a
parameter cannot be maximized for purposes of the SSRA data collection
while at the same time be properly maximized or minimized for purposes
of performance testing. It is additionally important to ensure that the
feed material used during the performance testing is appropriate for
SSRA emissions testing. When collecting emissions data for a SSRA,
testing with actual worst-case waste is preferred to ensure that the
testing material is representative of the toxic, persistence and
bioaccumulative characteristics of the waste that ultimately will be
burned. However, even if multiple tests need to be performed to
accomplish all of the objectives, it is still advantageous to conduct
these tests in the same general time frame to minimize mobilization and
sampling costs.
The timing of the required tests may cause difficulty for some
sources wishing to use coordinated testing. As we discussed in the May
1997 NODA, if the timing of the SSRA data collection does not coincide
with the MACT performance test requirement, the performance test should
not be unduly delayed. Commenters agree with this approach.
2. What Is Required for Risk Burn Testing?
We expect that sources for which coordinated testing is not
possible will need to obtain SSRA emissions data through a separate
risk burn. Similar to a traditional RCRA trial burn, risk burn testing
should be conducted pursuant to a test plan that is reviewed and
approved by the RCRA permitting authority. 40 CFR 270.10(k) provides
that the permitting authority may require the submittal of information
to establish permit conditions to ensure a facility's operations will
be protective of human health and the environment. This regulatory
requirement provides for the collection of emissions data, as
appropriate, for incorporation into a SSRA as well as for the
performance of the SSRA itself. We clarify in amendments to
Secs. 270.19, 270.22, 270.62 and 270.66 that the Director may apply
provisions from those sections, on a case-by-case basis, to establish a
regulatory framework for conducting the risk burn under Sec. 270.10(k)
and imposing risk-based conditions under Sec. 270.32(b)(2) (omnibus
provisions). This clarifying language is intended to prevent any
confusion from other language added to Secs. 270.19, 270.22, 270.62 and
270.66 today stating that
[[Page 52917]]
these provisions otherwise no longer apply once a source has
demonstrated compliance with the MACT standards and limitations of 40
CFR part 63, subpart EEE. (See Part Five, Section XI.B.3 for further
discussion.) Facilities and regulatory authorities may consult existing
EPA guidance documents for information regarding the elements of risk
burn testing.187
---------------------------------------------------------------------------
\187\ USEPA. ``Human Health Risk Assessment Protocol for
Hazardous Waste Combustion Facilities'' External Peer Review Draft.
EPA-530-D-98-001A,B&C. Date.; USEPA, ``Guidance on Collection of
Emissions Data to Support Site-Specific Risk Assessments at
Hazardous Waste Combustion Facilities'' EPA 530-D-98-002. August
1998.
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E. What Is a Change in Design, Operation, and Maintenance? (See
Sec. 63.1206(b)(6).)
The April 1996 NPRM noted that sources may change their design,
operation, or maintenance practices in a manner that may adversely
affect their ability to comply with the emission standards. These
sources would be required to conduct a new comprehensive performance
test to demonstrate compliance with the affected emission standards and
would be required to re-establish operating limits on the affected
parameters specified in Sec. 63.1209. (See 61 at FR 17518.) The
proposal stated that until a complete and accurate revised NOC is
submitted to the Administrator, sources would be permitted to burn
hazardous waste following such changes for time a period not to exceed
720 hours and only for the purposes of pretesting or comprehensive
performance testing. The approach in the April 1996 NPRM remains
appropriate, and we are adopting it in today's final rule with minor
modifications.
For changes made after submittal of your NOC that may adversely
affect compliance with any emission standard, as defined later in this
section, today's rule requires you to notify the Administrator at least
60 days prior to the change unless you document circumstances that
dictate that such prior notice is not reasonably feasible. The
notification must include a description of the changes and which
emission standards may be affected. The notification must also include
a comprehensive performance test schedule and test plan that will
document compliance with the affected emission standard(s). You must
conduct a comprehensive performance test to document compliance with
the affected emission standard(s) and establish operating parameter
limits as required and submit a revised NOC to the Administrator. You
also must not burn hazardous waste for more than a total of 720 hours
after the change and prior to submitting your NOC, and you must burn
hazardous waste during this time period only for the purposes of
pretesting or comprehensive performance testing.
Some commenters are uncomfortable with the proposed regulatory
language, stating that it was too generic and that the Agency could
require a comprehensive performance test even after minor changes in
maintenance practices. One commenter suggests that EPA incorporate a
list of changes significant enough to affect compliance, similar to
what is currently done in the RCRA permit modification classification
scheme in Appendix I of Sec. 270.42.
We intentionally proposed an approach that provides some degree of
flexibility to permit authorities. Individual facilities will need to
consult with these permit authorities who will make the decision on the
site-specific facts. We do not intend to require a comprehensive
performance test after minor modifications to system design, or after
implementing minor changes to operating or maintenance practices. We
considered incorporating sections of Appendix I of Sec. 270.42 to
further clarify when comprehensive performance tests would be
required.188 However, it is impossible to envision all
scenarios in which changes in design, operation, or maintenance
practices may or may not trigger the requirement of a complete, or even
partial, comprehensive performance test. Discussion of specific
scenarios is more suitable in an Agency guidance document as opposed to
regulatory provisions, and implemented on a site-specific basis. Thus,
the April 1996 NPRM set out the regulatory approach as well as can be
done, and we are adopting it today with minor modifications.
---------------------------------------------------------------------------
\188\ One approach would be to require performance tests for
modifications covered by the class 2 and class 3 permit
modifications associated with combustion source design and operating
parameter changes.
---------------------------------------------------------------------------
In the April 1996 NPRM, we did not address what must be done when
you change design, operation, or maintenance practices during the time
period between the compliance date and when you submit your NOC. If you
make a change during this time period, today's rule requires you to
revise your DOC, which is maintained on-site, to incorporate any
revised limits necessary to comply with the standards. For purposes of
this provision, today's rule defines ``change'' as any change in
reported design, operation, or maintenance practices you previously
documented to the Administrator in your comprehensive performance test
plan, NOC, DOC, or startup, shutdown, and malfunction plan.
Commenters point out that the proposal did not discuss
recordkeeping requirements necessary for the Administrator to determine
if you are adequately concluding that changes in design, operation, or
maintenance practices do not trigger a comprehensive performance test
requirement 189. As a result, today's rule requires you to
document in your operating record whenever you make a change (as
defined above) in design, operation, or maintenance practices,
regardless of whether the change may adversely affect your ability to
comply with the emission standards. See Sec. 63.1206(b)(6)(ii). You are
also required to maintain on site an updated comprehensive performance
test plan, NOC, and startup, shutdown, and malfunction plan that
reflect these changes. See Sec. 63.1211(c).
---------------------------------------------------------------------------
\189\ We cannot determine if a source has accurately concluded
that a change does not adversely affect its ability to comply with
the emission standards if we are never aware that changes were made
to the source.
---------------------------------------------------------------------------
F. What Are the Data In Lieu Allowances?
You are allowed to submit data from previous emissions tests in
lieu of performing a MACT performance test to set operating limits. See
Sec. 63.1207(c)(2). To use previous emissions test data, the data must
have been collected less than 5 years before the date you intend to
submit your notification of compliance. The data must also have been
collected as part of a test that was for the purpose of demonstrating
compliance with RCRA or CAA requirements. Additionally, you must submit
your request to use previous test data in your comprehensive
performance test plan which is submitted 1 year in advance of the MACT
performance test. Finally, you must schedule your subsequent MACT
performance test and MACT confirmatory test 5 years and 2.5 years
respectively following the date the emissions test data your submitting
was collected.
We developed this allowance in response to comments that suggested
we should allow previous RCRA testing to be used in lieu of performing
a new MACT performance test if the data could be used to demonstrate
compliance and establish operating limits to ensure compliance with the
MACT emissions standards. Commenters reasoned, and we agreed, that such
an allowance was reasonable and necessary for those sources that
[[Page 52918]]
must perform emissions tests to satisfy other state or federal
requirements. As we developed this allowance, we decided that it is
necessary to limit the age of the data and specify the date of the
following performance test because we need to be consistent with the
MACT performance test requirements with respect to testing frequency.
We can further justify the time and testing limitations of the data in
lieu of allowance by acknowledging that we don't want some sources
gaining an advantage over others by extending the date between
performance tests. However, we also weighed the fact that some sources
may be required to perform RCRA testing fairly close to the compliance
date or promulgation date of today's rule and we didn't want to
penalize them by forcing them to perform a new performance test before
five years had elapsed since their previous test. So we settled on an
approach that allows the use of previous emissions test data and
effectively sets the same testing frequency as is applied to test data
collected via a MACT performance test following the compliance date.
This approach doesn't penalize or favor any source over another and it
allows each source to take advantage of this provision when it makes
sense. For instance, a source may be granted approval to use data from
a RCRA trial burn performed 1 year before today's date, thus not
requiring the source to perform a comprehensive performance test 270
days following the compliance date. Instead, the source must schedule
its next MACT performance test five years after the date the test was
performed. However, the source must perform a confirmatory test 270
days following the compliance date because the test schedule for the
confirmatory test is also linked to the date of the performance test.
So in this situation the source must determine if its better to run the
comprehensive performance test on a normal schedule after the
compliance date or delay the comprehensive test and perform a
confirmatory test instead.
VI. What Is the Notification of Compliance?
A. What Are the Requirements for the Notification of Compliance?
You must submit to the Administrator the results of the
comprehensive performance test in a notification of compliance (NOC) no
later than three months after the conclusion of the performance test.
You must submit the initial NOC later than nine months following the
compliance date.
B. What Is Required in the NOC?
You must include the following information in the NOC:
--Results of the comprehensive performance test, continuous monitoring
system performance evaluation, and any other monitoring procedures or
methods that you conducted;
--Test methods used to determine the emission concentrations and
feedstream concentrations, as well as a description of any other
monitoring procedures or methods that you conducted;
--Limits for the operating parameters;
--Procedures used to identify the operating parameter limits specified
in Sec. 63.1209;
--Other information documenting compliance with the operating
requirements, including but not limited to automatic waste feed cutoff
system operability and operator training;
--A description of the air pollution control equipment and the
associated hazardous air pollutant that each device is designed to
control; and
--A statement from you or your company's responsible official that the
facility is in compliance with the standards and requirements of this
rule.
C. What Are the Consequences of Not Submitting a NOC?
The normal CAA enforcement procedures apply if you fail to submit a
timely notification of compliance. We do not adopt our proposed
approach that would have required you to immediately stop burning
hazardous waste if you failed to submit a timely NOC.
We proposed regulatory language stating that failure to submit a
notification of compliance by the required date would result in the
source being required to immediately stop burning hazardous waste. This
proposal was similar to requirements applied to BIFs certifying
compliance under RCRA. Under the proposal, if you wanted to burn
hazardous waste in the future, you would be required to comply with the
standards and permit requirements for new MACT and RCRA sources.
In the 1997 NODA, however, we proposed to rely on the regulating
agency's policy regarding enforcement response to govern the type of
enforcement response at a facility that fails to submit a notification
of compliance. Based on NODA comments and review of this enforcement
process, we are not including in the final rule regulatory language
addressing the consequences of failure to submit a timely or complete
NOC. Instead, we rely on the regulating agency's policy regarding
enforcement response to govern the type of enforcement response at a
facility that fails to meet a compliance deadline. This approach is
more practical to implementing today's MACT standards and is more
consistent with the way other MACT standards are implemented.
D. What Are the Consequences of an Incomplete Notification of
Compliance?
In response to our April 1996 NPRM, commenters state that we were
unclear as to the consequences of an incomplete NOC. Furthermore,
commenters state that it was important that we specify what is needed
and the consequences if an NOC is incomplete or more information is
needed. Additionally, commenters recommend that if the NOC contains
emission information, the certification statement, and a signature, we
should judge the NOC to be administratively complete and an acceptable
submission. In addition, commenters suggest that if the regulatory
official reviewing the NOC determines that additional information is
required, the source should be given ample time to submit that
information.
Our enforcement approach to incomplete submissions, under RCRA or
the CAA, is generally determined on a site-specific basis. We will not
attempt to foresee and develop enforcement responses to all the
possible levels of incompleteness for the NOC. This is beyond the scope
of our national rulemaking. Furthermore, defining what constitutes an
incomplete submission requires us to specifically prescribe a complete
submission, which is not possible for all situations or all source
designs. Some sources may require more detail than others in defining
the parameters necessary to determine compliance on a continuous basis.
Therefore, we instead define the minimum information necessary in the
submission and allow the implementing agency to determine if more
information is necessary in a facility's site-specific NOC.
In response to comments advocating that facilities be given ample
time to submit additional information required by the regulatory
official, we prefer to allow the implementing agency to determine the
time periods that will be granted to submit additional information
because some information requests may require widely varying degrees of
time and effort to develop. Many potential problems associated with
incomplete submissions can be prevented through interaction between
[[Page 52919]]
the source and the regulatory agency during the test plan review and
approval process. We do not want our rules to act as disincentive to
those discussions by providing a complete shield, regardless of the
severity of the omission.
E. Is There a Finding of Compliance?
We adopt the requirement we proposed for the regulatory agencies to
make a finding of compliance based on performance test results (see
Sec. 63.1206(b)(3)). This provision specifies that the regulatory
agency must determine whether an affected source is in compliance with
the emissions standards and other requirements of subpart EEE, as
provided by the general provisions governing findings of compliance in
Sec. 63.6(f)(3). Thus, the regulatory agency is obligated to make this
finding upon obtaining all the compliance information required by the
standards, including the written reports of performance test results,
monitoring results, and other applicable information. This includes,
but may not be limited to, the information submitted by the source in
its NOC.
VII. What Are the Monitoring Requirements?
In this section, we discuss the following topics: (1) The
compliance monitoring hierarchy that places a preference on compliance
with a CEMS; (2) how limits on operating parameters are established
from comprehensive performance test data; (3) status and use of CEMS
other than carbon monoxide, hydrocarbon, and oxygen CEMS; and (4) final
compliance monitoring requirements for each emission standard.
A. What Is the Compliance Monitoring Hierarchy?
We proposed the following three-tiered compliance monitoring
hierarchy in descending order of preference to ensure compliance with
the emission standards: (1) Use of a continuous emission monitoring
system (CEMS) for a hazardous air pollutant; (2) absent a CEMS for that
hazardous air pollutant, use of a CEMS for a surrogate of that
hazardous air pollutant and, when necessary, setting limits on
operating parameters to account for the limitations of using
surrogates; and (3) lacking a CEMS for either, requiring periodic
emissions testing and site-specific limits on operating parameters.
Accordingly, we proposed to require the use of carbon monoxide,
hydrocarbon, oxygen, particulate matter, and total mercury CEMS. We
also proposed performance specifications for multimetal, hydrochloric
acid, and chlorine gas CEMS to give sources the option of using a CEMS
for compliance with the semivolatile and low volatile metal emissions
standards, and the hydrochloric acid/chlorine gas emission standard.
Commenters question the availability and reliability of CEMS other
than those for carbon monoxide, hydrocarbon, and oxygen. We concur with
some of the commenters' concerns and are not requiring use of a total
mercury CEMS in the final rule or specifying the installation deadline
and performance specifications for particulate matter CEMS. In
addition, we have not promulgated performance specifications for these
CEMS or multimetal, hydrochloric acid, and chlorine gas CEMS. We
nonetheless continue to encourage sources to evaluate the feasibility
of using these CEMS to determine the performance specifications,
correlation acceptance criteria, and detector availability that can be
achieved. Sources may request approval from permitting officials under
Sec. 63.8(f) to use CEMS to document compliance with the emission
standards in lieu of periodic performance testing and compliance with
limits on operating parameters. See discussion in Section VII.C below
on these issues.
B. How Are Comprehensive Performance Test Data Used To Establish
Operating Limits?
In this section, we discuss: (1) The definitions of terms related
to monitoring and averaging periods; (2) the rationale for the
averaging periods for operating parameter limits, (3) how comprehensive
performance test data are averaged to calculate operating parameter
limits; (4) how the various types of operating parameters are
monitored/established; (5) how nondetect performance test feedstream
data are handled; and (6) how rolling averages are calculated
initially, upon intermittent operations, and when the hazardous waste
feed is cut off.
1. What Are the Definitions of Terms Related to Monitoring and
Averaging Periods?
In the April 1996 NPRM, we proposed definitions for several terms
that relate to monitoring and averaging periods. For the reasons
discussed below, we conclude that the proposed definitions are
appropriate and are adopting them in today's rule. We also finalize
definitions for ``average run average'' and ``average highest or lowest
rolling average'' which were not proposed. We conclude these new
definitions are necessary to clarify the meaning and intent of
regulatory provisions associated with the monitoring requirements that
are discussed in Part 5, Section VII.D. of this preamble.
We promulgate the following definitions in today's rule (see
Sec. 63.1201).
``Average highest or lowest rolling average'' means the average of
each run's highest or lowest rolling average run within the test
condition for the applicable averaging period.
``Average run average'' means the average of each run's average of
all associated one minute values.
``Continuous monitor'' means a device that: (1) Continuously
samples a regulated parameter without interruption; (2) evaluates the
detector response at least once every 15 seconds; and (3) computes and
records the average value at least every 60 seconds, except during
allowable periods of calibration and as defined otherwise by the CEMS
Performance Specifications in appendix B of part 60.
``Feedrate operating limits'' means limits on the feedrate of
materials (e.g., metals, chlorine) to the combustor that are
established based on comprehensive performance testing. The limits are
established and monitored by knowing the concentration of the limited
material (e.g., chlorine) in each feedstream and the flow rate of each
feedstream.
``Feedstream'' means any material fed into a hazardous waste
combustor, including, but not limited to, any pumpable or nonpumpable
solid, liquid, or gas.
``Flowrate'' means the rate at which a feedstream is fed into a
hazardous waste combustor.
``Instantaneous monitoring'' means continuously sampling,
detecting, and recording the regulated parameter without use of an
averaging period.
``One-minute average'' means the average of detector responses
calculated at least every 60 seconds from responses obtained at least
each 15 seconds.
``Rolling average'' means the average of all one-minute averages
over the averaging period.
One commenter opposes the requirement to take instrument readings
every 15 seconds. This commenter contends that such an approach is
simply impractical, unnecessary, and imposes a harsh burden upon
members of the regulated community. Another commenter maintains that
the CEMS Data Acquisition System should be capable of sampling the
analyzer outputs at least every 15 seconds. With today's processing
power and speed, the commenter states that this can easily be achieved.
We agree with the second commenter and are requiring instrument
[[Page 52920]]
readings at least every 15 seconds because this is currently required
in the Boilers and Industrial Furnace rulemaking. (See
Sec. 266.102(e)(6))
Another commenter states that the Agency's definition of
``instantaneous monitoring'' of combustion chamber pressure to control
combustion system leaks is not clear.190 The commenter
states that, although an instantaneous limit cannot be exceeded at any
time, continuous monitoring systems are required to detect parameter
values only once every 15 seconds. We note that the final rule requires
instantaneous monitoring only for the combustion chamber pressure limit
to control combustion system leaks. The rule requires an automatic
waste feed cutoff if the combustion chamber pressure at any time (i.e.,
instantaneously) exceeds ambient pressure (see Sec. 63.1209(p)). The
definition of a continuous monitoring system is that it must record
instrument readings at least every 15 seconds. For instantaneous
monitoring of pressure, the detector must clearly record a response
more frequently than every 15 seconds.191 It must detect and
record pressure constantly without interruption and without any
averaging period.
---------------------------------------------------------------------------
\190\ ``Combustion system leaks'' is the term used in today's
rule to refer to leaks that are called fugitive emissions under
current RCRA regulations. We use the term combustion system leaks to
refer to those emissions because the term fugitive emissions has
other meanings under part 63.
\191\ Typical pressure transducers in use today are capable of
responding to pressure changes once every fifty milliseconds. See
USEPA, ``Final Technical Support Document for Hazardous Waste
Combustor MACT Standards, Volume IV: Compliance with the Hazardous
Waste Combustor Standard,'' July 1999.
---------------------------------------------------------------------------
2. What Is the Rationale for the Averaging Periods for the Operating
Parameter Limits?
The final rule establishes the following averaging periods: (1) No
averaging period (i.e., instantaneous monitoring) for maximum
combustion chamber pressure to control combustion system leaks; (2) 12-
hour rolling averages for maximum feedrate of mercury, semivolatile
metals, low volatile metals, chlorine, and ash (for incinerators); and,
(3) one-hour averaging periods for all other operating parameters. As
discussed later in this section, we conclude that the proposed ten-
minute averaging periods are not necessary, on a national basis, to
better ensure compliance with the emission standards at hazardous waste
combustors, and have not adopted these averaging periods in this
rulemaking.
a. When Is an Instantaneous Limit Used? An instantaneous limit is
required only for maximum combustion chamber pressure to control
combustion system leaks. This is because any perturbation above the
limit may result in uncontrolled emissions exceeding the standards.
b. When Is an Hourly Rolling Average Limit Used? An hourly rolling
average limit is required for all parameters that are based on
operating data from the comprehensive performance test, except
combustion chamber pressure and feedrate limits. Hourly rolling
averages are required for these parameters rather than averaging
periods based on the duration of the performance test because we are
concerned that there may be a nonlinear relationship between operating
parameter levels and emission levels of hazardous air pollutants.
c. Why Has the Agency Decided Not to Adopt Ten-Minute Averaging
Periods? Dual ten-minute and hourly rolling averages were proposed for
most parameters for which limits are based on the comprehensive
performance test. See 61 FR at 17417. We proposed ten-minute rolling
averages in addition to hourly rolling averages for these parameters
because short term excursions of the parameter can result in a
disproportionately large excursion of the hazardous air pollutant being
controlled.
Commenters claim that the Agency's concerns with emission
excursions due to short term perturbations of these operating
parameters were not supported with data and are therefore unjustified,
and claim that averaging periods shorter than those required in the
existing BIF regulations would provide no environmental benefit.
We acknowledge that the Agency does not have extensive short-term
emission data that show operating parameter excursions can result in
disproportionately large excursions of hazardous air pollutants being
emitted. These short-term data cannot be obtained without the use of
continuous emission monitors that measure dioxin/furans, metals, and
chlorine on a real-time basis. Such monitors, for the most part, are
not currently used for compliance purposes at hazardous waste
combustors. However, known relationships between operating parameters
and hazardous air pollutant emissions indicate that a nonlinear
relationship exists between operating parameter levels and emissions.
This nonlinear relationship can result in source emissions that exceed
levels demonstrated in the performance test if the operating parameters
are not properly controlled. An explanation of these nonlinear
relationships, including examples that explain why this relationship
can result in daily emissions that exceed levels demonstrated in the
performance test, are included in the Final Technical Support
Document.192 Thus, at least in theory, an environmental
benefit can result from shorter averaging periods, including ten-minute
rolling averages and perhaps instantaneous readings in certain
situations.
---------------------------------------------------------------------------
\192\ See USEPA, ``Final Technical Support Document for
Hazardous Waste Combustor MACT Standards, Volume IV: Compliance With
the Hazardous Waste Combustor Standards, July 1999, Chapters 2 and
3.
---------------------------------------------------------------------------
We also acknowledge, however, that the Agency's ability to assess
this potential benefit in practice for all hazardous waste combustors
affected by this final rule is limited significantly by the paucity of
short-term, minute-by-minute, operating parameter data. Without this
data we cannot effectively evaluate whether operating parameter
excursions occur to an extent that warrant national ten-minute
averaging period requirements for all hazardous waste combustors. We
therefore conclude that averaging period requirements shorter than
those required by existing BIF regulations are not now appropriate for
adoption on a national level, and do not adopt ten-minute averaging
period requirements in this rulemaking.
We maintain, however, that there may be site-specific circumstances
that warrant averaging periods shorter than one hour in duration,
including possibly instantaneous measurements. Regulatory officials may
determine, on a site-specific basis, that shorter averaging periods are
necessary to better assure compliance with the emission standards. The
provisions in Sec. 63.1209(g)(2) authorize the regulatory official to
make such a determination. Factors that may be considered when
determining whether shorter averaging periods are appropriate include
(1) the ability of a source to effectively control operating parameter
excursions to levels achieved during the performance test; (2) the
source's previous compliance history regarding operating parameter
limit exceedances; and (3) the difference between the source's
performance test emission levels and the relevant emission standard.
For additional information, see the Final Technical Support Document,
Volume 4, Chapter 2.
d. What Is the Basis for 12-Hour Rolling Averages for Feedrates?
The rule requires 12-hour averages for the feedrate of mercury,
semivolatile metals, low volatile metals, chlorine, and ash (for
incinerators) because feedrate and emissions are, for the most part,
linearly
[[Page 52921]]
related. A 12-hour averaging period for feedrates is appropriate
because it is the upper end of the range of time required to perform
three runs of a comprehensive performance test. Thus, a 12-hour
averaging period will ensure (if all other factors affecting emissions
are constant) that emissions will not exceed performance test levels
during any interval of time equivalent to the time required to conduct
a performance test. A 12-hour averaging period is also achievable and
appropriate from a compliance perspective because the emission
standards are based on emissions data obtained over (roughly) these
sampling periods.193
---------------------------------------------------------------------------
\193\ See Chemical Waste Management v. EPA, 976 F.2d, 2, 34
(D.C. Cir. 1992) (It is inherently reasonable to base compliance on
the same type of data used to establish the requirement).
---------------------------------------------------------------------------
e. Has the Agency Over-Specified Compliance Requirements? Some
commenters state that the Agency is over-specifying compliance
requirements by requiring limits on many operating parameters,
requiring dual ten-minute and hourly rolling average limits on many
parameters, and requiring that sources interlock the operating
parameter limits with the automatic waste feed cutoff system. These
commenters wrote that this compliance regime may lead to system over-
control and instability, and an unreasonable and unnecessary increase
in automatic waste feed cutoffs, a result that is contrary to good
process control principles. They propose that we work with industry to
develop a process control system and performance specification
regulatory approach to establish minimum system standards. These would
include: (1) Minimum process instrument sampling time; (2) maximum
calculation capability for output signals; (3) minimum standard for
process control sequences; and (4) minimum requirements for
incorporating automatic waste feed cutoffs into the control scheme. The
specifications would be incorporated into guidance, rather than
regulation. Commenters suggest that the rule should only specify
general goals, similar to the guidance approach we took for hazardous
waste incinerators in the 1981 RCRA regulations.194
---------------------------------------------------------------------------
\194\ The incinerator regulations promulgated in 1981, at the
outset of the RCRA regulatory program, used such a general guidance
approach. However, sources have had over 15 years since then to gain
experience with process control techniques associated with the
combustion of hazardous waste.
---------------------------------------------------------------------------
We evaluated these comments carefully, balancing the need to
provide industry with operational flexibility with the need for
compliance assurance. As previously discussed, we are not adopting ten-
minute averaging period requirements in this rulemaking, although it
can be imposed on a site-specific basis under appropriate
circumstances. This addresses commenter's concerns that relate to the
complexity of the proposed dual averaging period requirements. We
acknowledge, however, that today's rule requires that more operating
parameter limits be interlocked to the automatic waste feed cutoff
system than is currently required by RCRA regulations. Nonetheless, we
conclude that the compliance regime of today's final rule is necessary
to ensure compliance with the emission standards and will not overly
constrain process control systems for the following reasons.
Automatic waste feed cutoffs are (by definition) automatic, and the
control systems used to avoid automatic waste feed cutoffs require
adequate response time and are primarily site-specific in design. The
closer a source pushes the edge of the operating envelope, the better
that control system must perform to ensure that an operating parameter
limit (and emission standard) is not exceeded. Therefore, a source has
extensive control over the impact of these requirements.
Under the compliance regime of today's rule, sources will continue
to perform comprehensive performance testing under ``worst case''
conditions as they currently do under RCRA requirements to establish
limits on operating parameters that are well beyond normal levels. This
cushion between normal operating levels and operating parameter limits
enables the source to take corrective measures well before a limit is
about to be exceeded, thus avoiding an automatic waste feed cutoff.
Regulatory officials do not have the extensive resources that would
be required to develop and implement industry-specific control
guidelines and we are not confident that this approach would provide
adequate compliance assurance. Although specifying only emissions
standards and leaving the compliance method primarily up to the source
and the permit writer (aided by guidance) would provide flexibility, it
would place a burden on the permit writers and the source during the
development and approval of the performance test plan and the finding
of compliance subsequent to Notification of Compliance. In addition,
this level of interaction between permitting officials and the source
is contrary to our policy of structuring the MACT standards to be as
self-implementing as possible.195 The Agency therefore
maintains its position that the compliance scheme adopted in today's
rule, is appropriate.
---------------------------------------------------------------------------
\195\ The time that would be associated with this type of review
and negotiation between permit writer and source would be better
spent on developing, reviewing, and approving the comprehensive
performance test plan under today's compliance regime.
---------------------------------------------------------------------------
f. Why Isn't Risk Considered in Determining Averaging Periods?
Several commenters state that long averaging periods (e.g., monthly
metal feedrate rolling averages) for the operating parameter limits and
CEMS-monitored emission standards would be appropriate. These
commenters believe that long averaging periods would be appropriate
given that the Agency has performed a risk assessment and concluded
that the emission standards would be protective over long periods of
exposure. They state that long averaging periods would ensure that
emissions are safe and reduce compliance costs.
Consideration of risk is not an appropriate basis for determining
averaging periods to ensure compliance with the technology-based MACT
emission standards.196 As previously stated, we must
establish averaging periods that ensure compliance with the emission
standard for time durations equivalent to the emission sampling periods
used to demonstrate compliance. Longer averaging periods would not
ensure compliance with the emission standard because many of the
operating parameters do not relate to emissions linearly.
---------------------------------------------------------------------------
\196\ We note, however, that within eight years of promulgating
MACT standards for a source category, we must consider risk in
determining under section 112(f) whether standards more stringent
than MACT are necessary to provide an ample margin of safety to
protect public health and the environment.
---------------------------------------------------------------------------
In addition, a longer averaging period is not warranted even for
those operating parameters than may relate linearly to emissions
because this would allow a source to emit hazardous air pollutants in
excess of the emission standard for times periods equivalent to the
stack emission sampling periods used to demonstrate compliance. For
example, a monthly averaging period for metal feedrates could result in
a source emitting metals at a level three times the regulatory standard
continuously for a one week period.197 This would not be
consistent with the level of control that was achieved by the best
performing sources in our data base. Modifying the results of the MACT
process based on risk considerations is thus contrary to Congressional
intent that MACT
[[Page 52922]]
standards, at a minimum, must represent the level of control being
achieved by the average of the best performing 12 percent of the
sources. We therefore conclude that we must limit averaging times at
least to time durations equivalent to the emission sampling periods
used to demonstrate compliance.
---------------------------------------------------------------------------
\197\ For this to occur, the source would have to emit metals
far below the standard for time periods before and after this one-
week period.
---------------------------------------------------------------------------
g. Will Relaxing Feedrate Averaging Times Increase Environmental
Loading? One commenter questions whether relaxing the averaging time
for the feedrate of metals and chlorine from an hourly rolling average
under current RCRA regulations to the 12-hour rolling average of
today's rule would increase total environmental loading of pollutants
and be counter to the Agency's pollution prevention objectives.
Contrary to the commenter's concern, we conclude that today's rule will
decrease environmental loading of hazardous air pollutants because the
emission standards are generally more stringent than current RCRA
standards. Today's standards more than offset any difference in
environmental loading associated with longer averaging times. As
previously discussed, the averaging periods in today's rule were chosen
to ensure compliance with the emission standard for intervals of time
equivalent to the time required to conduct a performance test.
Although current RCRA standards generally establish hourly rolling
averages for the feedrate of metals, sources are actually allowed to
establish up to 24-hour rolling averages for arsenic, beryllium,
chromium, cadmium, and lead, provided they restrict the feedrate of
these metals at any time to ten times what would be normally allowed
under an hourly rolling average basis. For these reasons, the
commenter's concern is not persuasive.
3. How Are Performance Test Data Averaged To Calculate Operating
Parameter Limits?
The rule specifies which of two techniques you must use to average
data from the comprehensive performance test to calculate limits on
operating parameters: (1) Calculate the limit as the average of the
maximum (or minimum, as specified) rolling averages for each run of the
test; or (2) calculate the limit as the average of the test run
averages for each run of the test.
Hourly rolling averages for two parameters--combustion gas flowrate
(or kiln production rate as a surrogate) and hazardous waste feedrate--
are based on the average of the maximum hourly rolling averages for
each run. Hourly rolling average and 12-hour rolling average limits for
all other parameters, however, are based on the average level occurring
during the comprehensive performance test. We determined that this more
conservative approach is appropriate for these parameters because they
can have a greater effect on emissions, and because it is consistent
with how manual method emissions results are determined.198
---------------------------------------------------------------------------
\198\ Manual method emission test results for each run
represents average emissions over the entire run.
---------------------------------------------------------------------------
These are examples of how the averages work. The hourly rolling
average hazardous waste feedrate limit for a source is calculated using
the first technique. If the highest hourly rolling averages for each
run of the comprehensive performance test were 200 lbs/hour, 210 lbs/
hr, 220 lbs/hr, the hourly rolling average feedrate limit would be 210
lbs/hr.
The second approach uses the average of the test run averages for a
given test condition to calculate the limit. Each test run average is
calculated by summing all the one-minute readings within the test run
and dividing that sum by the number of one-minute readings. For
example, if: (1) The sum of all the one-minute semivolatile metal
feedrate readings for each run within a test condition is 2,400 lbs/
hour, 2,500 lbs/hour, and 2,600 lbs/hour; and (2) there are 240, 250,
and 200 one-minute readings in each run, respectively; then (3) the
average feedrate for each of these three runs is 10 lbs/hour, 10 lbs/
hour, and 13 lbs/hour, respectively. The 12-hour rolling average
semivolatile metal feed rate limit for this example is the average of
these three values: 11 lbs/hour. This averaging methodology is not
equivalent to an approach where the limit is calculated by taking the
time-weighted average over all three runs within the test condition,
because, as noted by the example, sampling times may be different for
each run. The time-weighted average feedrate over all three test runs
for the previous example is equivalent to 10.9 lbs/hr.199
Although the two averaging techniques may not result in averages that
are significantly different, we conclude that basing the limits on the
average of the test run averages is more appropriate, because this
approach is identical to how we determine compliance with the emission
standards.
---------------------------------------------------------------------------
\199\ This time weighted average is calculated by summing all
the one-minute feedrate values in the test condition and dividing
that sum by the number of one minute readings in the test condition.
---------------------------------------------------------------------------
These averaging techniques are the same as we proposed (see 61 FR
at 17418).200 A number of commenters object to the more
conservative second technique of basing the limits on the average
levels that occur during the test. The commenters claim that this
approach ensures a source would not comply with the limits 50% of the
time when operating under the same conditions as the performance test.
Further, they are concerned that this approach would establish
operating parameter limits that would ``ratchet'' emissions to levels
well below the standards, and further ratcheting would occur with each
subsequent performance test (i.e., because the current operating limits
could not be exceeded during subsequent performance testing). Some
commenters prefer the approach of setting the limit as the average of
the highest (or lowest) rolling average from each run, technique one
above, which is the same approach used in the BIF rule.
---------------------------------------------------------------------------
\200\ Except that average hourly rolling average limits are
calculated as the average of the test run averages rather than
simply the average over all runs as proposed.
---------------------------------------------------------------------------
Notwithstanding the conservatism of the promulgated approach
(technique two above) for many operating parameter limits, we maintain
that the approach results in achievable limits and is necessary to
ensure compliance with the emission standards. Comprehensive
performance tests are designed to demonstrate compliance with the
emission standards and establish corresponding operating parameter
limits. Thus, sources will operate under ``worst-case'' conditions
during the comprehensive performance tests, just as they do currently
for RCRA trial burns. Given that the source can readily control (during
the performance test and thereafter) the parameters for which limits
are established based on the average of the test run averages during
performance testing (i.e., rather than on the average of the highest
(or lowest) hourly rolling averages), and that these parameters will be
at their extreme levels during the performance test, the limits are
readily achievable.
There may be situations, however, where a source cannot
simultaneously demonstrate worst-case operating conditions for all the
regulated operating parameters. An example of this may be minimum
combustion chamber temperature and maximum temperature at the inlet to
the dry particulate matter control device because when the combustion
chamber temperature is minimized, the inlet temperature to the control
device may also be minimized. Sources should consult permitting
officials to resolve
[[Page 52923]]
compliance difficulties associated with conflicting operating
parameters. Potential solutions to conflicting parameters could be to
conduct the performance test under two different modes of operation to
set these conflicting operating parameter limits, or for the
Administrator to use the discretionary authority provided by
Sec. 63.1209(g)(2) to set alternative operating parameter limits.
We address commenters' concern that subsequent performance tests
would result in a further ratcheting down of operating parameter limits
by waiving the operating limits during subsequent comprehensive
performance tests (see Sec. 63.1207(h)). The final rule also waives
operating limits for pretesting prior to comprehensive performance
testing for a total operating time not to exceed 720 hours. See
discussion in Part Five, Section VI for more information on this
provision.
Some commenters suggest that we use a statistical analysis to
determine rolling average limits, such that the limits are calculated
as the mean plus or minus three standard deviations of all rolling
averages for all runs. Commenters state that this would ensure that the
operating parameter limits are achievable. If such an approach were
adopted, there would be no guarantee that a source is maintaining
compliance with the emission standards for the time durations of the
manual stack sampling method used to demonstrate compliance during the
comprehensive performance test. Such an approach could conceivably
encourage a source to intentionally vary operating parameter levels
during the comprehensive performance test to such an extent that the
statistically-derived rolling average limits would be significantly
higher than the true average of the test condition. This could also
result in widely varying statistical correction factors from one source
to another, which is undesirable for reasons of consistency and
fairness.
Such a statistical approach prevents us from establishing the
minimum emission standards that Congress generally envisioned under
MACT because we would not be assured that the sources are achieving the
emission standard. We would also have difficulty estimating
environmental benefits if this statistical approach were used because
we would not know what level of emission control each source achieves.
Again, the methodology promulgated for averaging performance test data
to calculate operating parameter limits results in limits that are
achievable and necessary to ensure compliance with the emission
standards for time durations equivalent to emission sampling periods.
Several commenters oppose the compliance regime whereby limits on
operating parameters are established during performance testing. They
are concerned that this approach encourages sources to operate under
worst-case conditions during testing. One commenter states that this
approach effectively punishes sources for demonstrating emissions
during their performance test that are lower than the standards (i.e.,
by establishing limits on operating parameters that would be well below
those needed to comply with the standards).
We understand these concerns, but absent the availability of
continuous emissions monitoring systems, we are unaware of another
compliance assurance approach that effectively addresses the (perhaps
unique) problem posed by hazardous waste combustors. The Agency is
using this same approach to implement the RCRA regulations for these
sources. Compliance assurance for hazardous waste combustors cannot be
maintained using the general provisions of Subpart A in Part 63--
procedures that apply to all MACT sources unless we promulgate
superseding provisions for a particular source category. Those
procedures require performance testing under normal operating
conditions, but operating limits are not established based on
performance test operations. This approach is appropriate for most
industrial processes because process constraints and product quality
typically limit ``normal'' operations to a fairly narrow range that is
easily defined.
Hazardous waste combustors may be somewhat unique MACT sources,
however, in that the characteristics of the hazardous waste feed (e.g.,
metals concentration, heating value) can vary over a wide range and
have a substantial effect on emissions of hazardous air pollutants. In
addition, system design, operating, and maintenance features can
substantially affect pollutant emissions. This is not the same
situation for many other MACT source categories where feedstream
characteristics and system design, operation, and maintenance features
must be confined to a finite range so that the source can continue to
produce a product. Hazardous waste incinerators do not have such
inherent controls (i.e., because they provide a waste treatment service
rather than produce a product), and cement and lightweight aggregate
kilns can vary substantially hazardous waste characteristics in the
fuel, as well as system design, operation, and maintenance features and
still produce marketable product.
To address commenters' concerns at least in part, however, we have
included a metals feedrate extrapolation provision in the final rule.
This will reduce the incentive to spike metals in feedstreams during
performance testing (and thus reduce the cost of testing, the hazard to
test crews, and the environmental loading) by explicitly allowing
sources to request approval to establish metal feedrate limits based on
extrapolating upward from levels fed during performance testing. See
discussion in Section VII.D.4 below, and Secs. 63.1209(l)(1) and
63.1209(n)(2)(ii).
4. How Are the Various Types of Operating Parameters Monitored or
Established?
The operating parameters for which you must establish limits can be
categorized according to how they are monitored or established as
follows: (1) Operating parameters monitored directly with a continuous
monitoring system; (2) feedrate limits; and (3) miscellaneous operating
parameters. (Each of these parameters is discussed in Section VII.D
below.)
a. What Operating Parameters Are Monitored Directly with a
Continuous Monitoring System? Operating parameters that are monitored
directly with a continuous monitoring system include: Combustion gas
temperature in the combustion chamber and at the inlet to a dry
particulate matter control device; baghouse pressure drop; for wet
scrubbers, pressure drop across a high energy wet scrubber (e.g.,
venturi, calvert), liquid feed pressure, pH, liquid-to-gas ratio,
blowdown rate (coupled with either a minimum recharge rate or a minimum
scrubber water tank volume or level), and scrubber water solids
content; minimum power input to each field of an electrostatic
precipitator; flue gas flowrate or kiln production rate; hazardous
waste flowrate; and adsorber carrier stream flowrate. These operating
parameters are monitored and recorded on a continuous basis during the
comprehensive performance test and during normal operations. The
continuous monitoring system also transforms and equates the data to
its associated averaging period during the performance test so that
operating parameter limits can be established. The continuous
monitoring system must operate in conformance with Sec. 63.1209(b).
b. How Are Feedrate Limits Monitored? Feedrate limits are monitored
by knowing the concentration of the regulated parameter
[[Page 52924]]
in each feedstream and continuously monitoring the flowrate of each
feedstream. See Sec. 63.1209(c)(4). You must establish limits on the
feedrate parameters specified in Sec. 63.1209, including: semivolatile
metals, low volatile metals, mercury; chlorine, ash (for incinerators),
activated carbon, dioxin inhibitor, and dry scrubber sorbent. The
flowrate continuous monitoring system must operate in conformance with
Sec. 63.1209(b).
c. How Are the Miscellaneous Operating Parameters Monitored/
Established? Other operating parameters specified in Sec. 63.1209
include: Specifications for activated carbon, acid gas sorbent,
catalyst for catalytic oxidizers, and dioxin inhibitor; and maximum age
of carbon in a carbon bed. Because each of these operating parameters
may be unique to your source, you are expected to characterize the
parameter (e.g., using manufacturer specifications) and determine how
it will be monitored and recorded. This information must be included in
the comprehensive performance test plan that will be reviewed and
approved by permitting officials.
5. How Are Rolling Averages Calculated Initially, Upon Intermittent
Operations, and When the Hazardous Waste Feed Is Cut Off?
a. How Are Rolling Averages Calculated Initially? You must begin
complying with the limits on operating parameters specified in the
Documentation of Compliance on the compliance date.201 See
Sec. 63.1209(b)(5)(i). Given that the one-hour, and 12-hour rolling
averages for limits on various parameters must be updated each minute,
this raises the question of how rolling averages are to be calculated
upon initial startup of the rolling average requirements. We have
determined that an operating parameter limit will not become effective
on the compliance date until you have recorded enough monitoring data
to calculate the rolling average for the limit. For example, the hourly
rolling average limit on the temperature at the inlet to an
electrostatic precipitator does not become effective until you have
recorded 60 one-minute average temperature values on the compliance
date. Given that compliance with the standards begins nominally at
12:01 am on the compliance date, the hourly rolling average temperature
limit does not become effective as a practical matter until 1:01 am on
the compliance date. Similarly, the 12-hour rolling average limit on
the feedrate of mercury does not become effective until you have
recorded 12 hours of one-minute average feedrate values after the
compliance date. Thus, the 12-hour rolling average feedrate limits
become effective as a practical matter at 12:01 pm on the compliance
date.
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\201\ The operating parameters for which you must specify limits
are provided in Sec. 63.1209. You must include these limits in the
Documentation of Compliance, and you must record the Documentation
of Compliance in the operating record.
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Although we did not specifically address this issue at proposal,
commenters raised the question in the context of CEMS. Given that the
same issue applies to all continuous monitoring systems, we adopt the
same approach for all continuous monitoring systems, including CEMS.
See discussion below in Section VII.C.5.b. We adopt the approach
discussed here because a rolling average limit on an operating
parameter does not exist until enough one-minute average values have
been obtained to calculate the rolling average.
b. How Are Rolling Averages Calculated upon Intermittent
Operations? We have determined that you are to ignore periods of time
when one-minute average values for a parameter are not recorded for any
reason (e.g., source shutdown) when calculating rolling averages. See
Sec. 63.1209(b)(5)(ii). For example, consider how the hourly rolling
average for a parameter would be calculated if a source shuts down for
yearly maintenance for a three week period. The first one-minute
average value recorded for the parameter for the first minute of
renewed operations is added to the last 59 one-minute averages before
the source shutdown for maintenance to calculate the hourly rolling
average.
We adopt this approach for all continuous monitoring systems,
including CEMS (see discussion below in Section VII.C.5.b) because it
is simple and reasonable. If, alternatively, we were to allow the
``clock to be restarted'' after an interruption in recording parameter
values, a source may be tempted to ``clean the slate'' of high values
by interrupting the recording of the parameter values (e.g., by taking
the monitor off-line for a span or drift check). Not only would this
mean that operating limits would not be effective again until an
averaging period's worth of values were recorded, but it would be
contrary to our policy of penalizing a source for operating parameter
limit exceedances by not allowing hazardous waste burning to resume
until the parameter is within the limit. Not being able to burn
hazardous waste during the time that the parameter exceeds its limit is
intended to be an immediate economic incentive to minimize the
frequency, duration, and intensity of exceedances.
c. How Are Rolling Averages Calculated when the Hazardous Waste
Feed Is Cut Off? Even though the hazardous waste feed is cut off, you
must continue to monitor operating parameters and calculate rolling
averages for operating limits. See Sec. 63.1209(b)(5)(iii). This is
because the emission standards and operating parameter limits continue
to apply even though hazardous waste is not being burned. See, however,
the discussion in Part Five, Sections I.C and I.D above for exceptions
(i.e., when a hazardous waste combustor is not burning hazardous waste,
the emission standards and operating requirements do not apply: (1)
During startup, shutdown, and malfunctions; or (2) if you document
compliance with other applicable CAA section 112 or 129 standards).
6. How Are Nondetect Performance Test Feedstream Data Handled?
You must establish separate feedrate limits for semivolatile metal,
low volatile metal, mercury, total chlorine, and/or ash for each
feedstream for which the comprehensive performance test feedstream
analysis determines that these parameters are not present at detectable
levels. The feedrate limit must be defined as nondetect at the full
detection limit achieved during the performance test. See
Sec. 63.1207(n).
You will not be deemed to be exceeding this feedrate limit when
detectable levels of the constituent are measured, provided that: (1)
Your total system constituent feedrate, considering the detectable
levels in the feedstream (whether above or below the detection limit
achieved during the performance test) that is limited to nondetect
levels, is below your total system constituent feedrate limit; or (2)
except for ash, your uncontrolled constituent emission rate for all
feedstreams, calculated in accordance with the procedures outlined in
the performance test waiver provisions (see Sec. 63.1207(m)) are below
the applicable emission standards.
We did not address in the April 1996 NPRM how you must handle
nondetect compliance test feedstream results when determining feedrate
limits, nor did commenters suggest an approach. After careful
consideration, we conclude that the approach presented above is
reasonable and appropriate.
The LWAK industry has expressed concern about excessive costs with
compliance activities that would be needed for the mercury standard.
They
[[Page 52925]]
claim that the increased costs associated with achieving lower mercury
detection limits are large, and does not result in significant
environmental benefits.
The final rule includes four different methods an LWAK can use to
comply with the mercury emission standard in order to provide maximum
flexibility. The basic compliance approach (described below) does not
require an LWAK to achieve specified minimum mercury detection limits
for mercury standard compliance purposes.202 Under this
approach, analytical procedures that achieve given detection limits are
evaluated on a site-specific basis as part of the waste analysis plan
review and approval process, which is submitted as part of the
performance test plan. An LWAK can make the case to the regulatory
official that the increased costs associated with achieving a very low
mercury detection limit is not warranted. We therefore do not believe
that the LWAK industry will incur significant additional analytical
costs over current practices for daily mercury compliance activities.
We acknowledge, however, that site-specific circumstances may lead a
regulatory official to conclude that lower detection limits are
warranted. To better understand this concept, the following paragraphs
summarize this basic mercury emission standard compliance scheme and
discusses why a regulatory official may determine, on a site-specific
basis, that lower detection limits are needed to better assure
compliance with the emission standard.
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\202\ The other three approaches are (1) performance test waiver
provisions (see preamble, part 5, section X.B); (2) alternative
standards when raw materials cause an exceedance of the emission
standard (see preamble, part 5, section X.A); and, (3) alternative
mercury standards for kilns that have non-detect levels of mercury
in the raw material (see preamble, part 5, section X.A). These
mercury standard compliance alternatives require a source to achieve
feedstream detection limits that either ensure compliance with an
emission standard or ensure compliance with a hazardous waste
feedrate limit that is used in lieu of a numerical emission
standard. See previous referenced preamble for further discussion.
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Under this basic approach, the source conducts a performance test
and samples the emissions for mercury to demonstrate compliance with
the emission standard. To ensure compliance with the emission standard
during day-to-day operations, the source must comply with mercury
feedrate limits that are based on levels achieved during the
performance test. A source must establish separate mercury feedrate
limits for each feed location. As previously discussed in this section,
for feedstreams where mercury is not present at detectable levels, the
feedrate limit must be defined as ``nondetect at the full detection
limit''.
There is no regulatory requirement for a source to achieve a given
detection limit under this approach. We acknowledge, however, that
feedstream detection limits can be high enough such that a mercury
feedrate limit that is based on nondetect performance test results may
not completely ensure compliance with the emission standard during day-
to-day operations. For example, the LWAK industry has indicated that a
hazardous waste mercury detection limit of 2 ppm is reasonably
achievable at an on-site laboratory. If we assume that mercury is
present in the hazardous waste at a concentration of 1.99 ppm (just
below the detection limit), the expected mercury emission concentration
would be approximately 80 g/dscm, which is above the
standard.203 (Note also that this does not consider mercury
emission contributions from the raw material.) This is not to say that
this LWAK will be exceeding the mercury emission standard during day-
to-day operations. However, their inability to achieve low mercury
detection limits results in less assurance that the source is
continuously complying with the emission standard.
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\203\ This assumes that all the mercury fed to the unit is
emitted, and is based on typical LWAK gas emission rates.
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The regulatory official should consider such emission standard
compliance assurance concerns when reviewing the waste analysis plan to
determine if lower detection limits are appropriate (if, in fact such
lower detection limits are reasonably achievable). Factors that should
be considered in this review should include: (1) The costs associated
with achieving lower detection limits; and (2) the estimated maximum
mercury concentrations that can occur if the source's feedstreams
contain mercury just below the detection limit (as described above).
C. Which Continuous Emissions Monitoring Systems Are Required in the
Rule?
Although the final rule does not require you to use continuous
emissions monitoring systems (CEMS) for parameters other than carbon
monoxide, hydrocarbon, oxygen, and particulate matter 204 we
have a strong preference for CEMS because they: (1) Are a direct
measure of the hazardous air pollutant or surrogate for which we have
established emission standards; (2) lead to a high degree of certainty
regarding compliance assurance; and (3) allow the public to be better
informed of what a source's emissions are at any time. Additionally,
from a facility standpoint, CEMs provide you with real time feedback on
your combustion operations and give you a greater degree of process
control. Therefore, we encourage you to use CEMS for other parameters
such as total mercury, multimetals, hydrochloric acid, and chlorine
gas. You may use the alternative monitoring provision of Sec. 63.8(f)
to petition the Administrator (i.e., permitting officials) to use CEMS
to document compliance with the emission standards in lieu of emissions
testing and the operating parameter limits specified in Sec. 63.1209.
You may submit the petition at any time, such as with the comprehensive
performance test plan. See Section VII.C.5.c below for a discussion of
the incentives for using CEMS.
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\204\ The final rule requires that particulate matter CEMS be
installed, but defers the effective date of the requirement to
install, calibrate, maintain, and operate PM CEMS until these
actions can be completed.
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In this section, we discuss the status of development of particular
CEMS and provide guidance on issues that pertain to case-by-case
approval of CEMS in lieu of compliance using operating parameter limits
and periodic emissions testing. Key issues include appropriate CEMS
performance specifications, reference methods for determining the
performance of CEMS, averaging periods, and temporary waiver of
emission standards if necessary to enable sources to correlate
particulate matter CEMS to the reference method.
1. What Are the Requirements and Deferred Actions for Particulate
Matter CEMS?
In the April 1996 NPRM, we proposed the use of particulate matter
CEMS to document compliance with the particulate matter emission
standards. Particulate matter CEMS are used for compliance overseas
205, but are not yet a regulatory compliance tool in the
U.S. Concurrent with this proposal, we undertook a demonstration of
particulate matter CEMS at a hazardous waste incinerator to determine
if these CEMS were feasible in U.S. applications. We selected the test
incinerator as representative of a worst-case application for a
particulate matter CEMS at any hazardous waste
[[Page 52926]]
combustor. It was important to document feasibility of the CEMS at a
worst-case application to minimize time and resources needed to
determine whether the CEMS were suitable for compliance assurance at
all hazardous waste combustors.
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\205\ The EU guidelines for hazardous waste combustion state
that particulate matter is a parameter for which compliance must be
documented continuously. In addition, proposals from vendors that we
received in response to our February 27, 1996 NODA (see 61 FR 7262)
indicate that there are many installations elsewhere overseas where
particulate matter CEMS are used for compliance assurance.
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We published preliminary results of our CEMS testing and sought
comment on our approach to demonstrating particulate matter CEMS in the
March 1997 NODA. We then revised our approach and sought comment on the
final report in the December 1997 NODA. The December 1997 NODA also
clarified several issues that came to light during the demonstration
test pertaining to the manual reference method, particulate matter
CEMS, and general quality assurance issues. These clarifications were
embodied in a new manual method, Method 5-I (Method 5i), a revision to
the proposed Performance Specification 11 for particulate matter CEMS,
and a new quality assurance procedure, Procedure 2.
We believe that our tests adequately demonstrate that particulate
matter CEMS are a feasible, accurate, and reliable technology that can
and should be used for compliance assurance. In addition, preliminary
analyses of the cost of PM CEMS applied to hazardous waste combustors
suggest that these costs are reasonable. Accordingly, the final rule
contains a requirement to install PM CEMS. However, we agree with
comments that indicate a need to develop source-specific performance
requirements for particulate matter CEMS and to resolve other
outstanding technical issues. These issues include all questions
related to implementation of the particulate matter CEMS requirement
(i.e. relation to all other testing, monitoring, notification, and
recordkeeping), relation of the particulate matter CEMS requirement to
the PM emission standard, as well as technical issues involving
performance, maintenance and correlation of the particulate matter CEMS
itself. These issues will be addressed in a subsequent rulemaking.
Therefore, we defer the effective date of this requirement pending
further testing and additional rulemaking.
As a result, in today's final rule, we require that particulate
matter CEMS be installed at all hazardous waste burning incinerators,
cement kilns, and lightweight aggregate kilns. However, since we have
not finalized the performance specifications for the use of these
instruments or resolved some of the technical issues noted above, we
are deferring the effective date of the requirement to install,
calibrate, maintain and operate particulate matter CEMS until these
actions can be completed. The particulate matter CEMS installation
deadline will be established through future rulemaking, along with
other pertinent requirements, such as final Performance Specification
11, Appendix F Procedure 2. Finally, it should be noted that EPA has a
concurrent rulemaking process underway for nonhazardous waste burning
cement kilns and plans to adopt the same approach in that rule.
2. What Are the Test Methods, Specifications, and Procedures for
Particulate Matter CEMS?
a. What Is Method 5i? We promulgate in the final rule a new manual
method for measuring particulate matter, Method 5i. See appendix A to
part 60. We first published this new method in the December 1997 NODA.
One outgrowth of these particulate matter CEMS demonstration tests is
that we made significant improvements in making low concentration
Method 5 particulate measurements. We first discussed these
improvements in the preliminary report released in the March 1997 NODA,
and commenters to that NODA ask that these improvements be documented.
We documented these improvements by creating Method 5i.
We incorporated the following changes to Method 5 into Method 5i:
Improved sample collection; minimization of possible contamination;
Improved sample analysis; and an overall emphasis on elimination of
systemic errors in measurement. These improvement achieved significant
improvements in method accuracy and precision at low particulate matter
concentrations, relative to Method 5.
We are promulgating Method 5i today, in advance of any particulate
matter CEMS requirement, for several reasons. We expect this new method
will be preferred in all cases where low concentration (i.e., below 45
mg/dscm (0.02 gr/dscf) 206) measurements are
required for compliance with the standard. Given that all incinerators,
nearly all lightweight aggregate kilns, and some cement kilns are
likely to have emissions lower than 45 mg/dscm, we expect that Method
5i will become the particulate method of choice for most hazardous
waste combustors. In addition, we expect that Method 5i will be used to
correlate manual method results to particulate matter CEMS outputs for
those sources that elect to petition the Administrator to use a CEMS in
lieu of operating parameter limits for compliance assurance with the
particulate matter standard.207 This is because, unlike the
worst-case particulate matter measurements normally used to verify
compliance with the standard, low (or lower than normal) concentration
particulate matter data are required to develop a good correlation
between the CEMS output and the manual, reference method.
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\206\ As noted later in the text, the filter and assembly used
for Method 5i is smaller than the one used for Method 5. This means
that the Method 5i filter plugs more easily than the one used for
Method 5. This issue becomes important at particulate matter
concentrations above 45 mg/dscm, or 0.02 gr/dscf.
\207\ As alluded to previously, sources may elect to use a CEMS
to comply with the numerical value of the particulate matter
emission standard on a six-hour rolling average in lieu of complying
with operating parameter limits specified by Sec. 63.1209(m).
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Many of the issues commenters raise relate to how Method 5i should
be used to correlate particulate matter CEMS outputs to manual method
measurements. Even though we are deferring a CEMS requirement, we
address several key issues here given that sources may elect to
petition the Administrator under Sec. 63.8(f) to use a CEMS. This
discussion may provide a better understanding on our thinking on
particulate matter CEMS issues. In addition, certain comments are
specific to how Method 5i is performed. These comments and our
responses are relevant even if you use Method 5i only as a stack
particulate method and not to correlate a particulate matter CEMS to
the reference method.
i. Why Didn't EPA Validate Method 5i Against Method 5? Several
commenters recommend that we perform a full Method 301 validation to
confirm that Method 5i is equivalent to Method 5. We determined that a
full Method 301 validation is not necessary because the differences in
the two methods do not constitute a major change in the way particulate
samples are collected from an operational or an analytical standpoint.
We validated the filter extraction and weighting process--the only
modification from Method 5 (see ``Particulate Matter CEMS Demonstration
Test Final Report,'' Appendix A, in the Technical Support Document
208) `` and documented that Method 5i gives nearly identical
results as Method 5. Therefore, we disagree with the commenters'
underlying concern and conclude that Method 5i has been validated.
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\208\ See USEPA, ``Final Technical Support Document for
Hazardous Waste Combustor MACT Standards, Volume IV: Compliance With
the Hazardous Waste Combustor Standards,'' July 1999.
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ii. When Are Paired Trains Required? We have included in Method 5i
a requirement that paired trains must be
[[Continued on page 52927]]