United States Office of Air Quality EPA-450/3-81-009c
Environmental Protection Planning and Standards January 1984
Agency Research Triangle Park NC 27711
Metallic Mineral Final
Processing Plants - EIS
Background
Information
for Promulgated
Standards
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EPA-450/3-81-009c
Metallic Mineral
Processing Plants -
Background Information
for Promulgated Standards
Emission Standards and Engineering Division
U.S ENVIRONMENTAL PROTECTION AGENCY
Office of Air, Noise, and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
January 1984
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This report has been reviewed by the Emission Standards and Engineering Division of the Office of Air Quality Planning
and Standards, EPA, and approved for publication. Mem ion of trade names or commercial products is not intended to
constitute endorsement or recommendation for use. Copies of this report are available through the Library Services
Office (MD-35), U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711; or, for a fee, from
the National Technical Information Services, 5285 Port Royal Road, Springfield, Virginia 22161.
Publication No. EPA-450/3-81-009c
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ENVIRONMENTAL PROTECTION AGENCY
Background Information and
Final Environmental Impact Statement for
Metallic Mineral Processing Plants
Prepared by:
Jcfck R. Farmer (Date)
Director, Emission Standards and Engineering Division
U.S. Environmental Protection Agency
Research Triangle Park, N.C. 27711
1. The promulgated standards of performance will limit emissions of
particulate matter from new, modified, and reconstructed metallic
mineral processing plants. Section 111 of the Clean Air Act
(42 U.S.C. 7411), as amended, directs the Administrator to establish
standards of performance for any category of new stationary source
of air pollution that ". . . causes or contributes significantly to
air pollution which may reasonably be anticipated to endanger public
health or welfare." The promulgated standards of performance are
expected to affect mostly the western states.
2. Copies of this document have been sent to the following Federal
Departments: Office of Management and Budget, Labor, Health and
Human Services, Defense, Transportation, Agriculture, Commerce,
Interior, and Energy; the National Science Foundation; the Council
on Environmental Quality; State and Territorial Air Pollution
Program Administrators; the Association of Local Air Pollution
Control Officials; EPA Regional Administrators; and other interested
parties.
3. For additional information contact:
Mr. C. Douglas Bell
Standards Development Branch (MD-13)
U.S. Environmental Protection Agency
Research Triangle Park, N.C. 27711
Telephone: (919) 541-5624
4. Copies of this document may be obtained from:
U.S. EPA Library (MD-35)
Research Triangle Park, N.C. 27711
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
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TABLE OF CONTENTS
Section
1.
2.
Summary
1.1 Summary of Changes Since Proposal ....
1.2 Summary of the Impacts of the Promulgated
Action
Page
1-1
1-1
1-2
Summary of Public Comments 2-1
2.1 General 2-1
2.2 Emission Control Technology 2-16
2.3 Modification and Reconstruction 2-25
2.4 Economic Impact 2-30
2.5 Environmental Impact 2-33
2.6 Energy Impact 2-37
2.7 Test Methods and Monitoring 2-38
Number
2-1
LIST OF TABLES
List of Commenters on the Proposed Standards of
Performance for Metallic Mineral Processing .
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1. SUMMARY
On August 24, 1982, the U.S. Environmental Protection Agency (EPA)
proposed new source performance standards (NSPS) for metallic mineral
processing plants under the authority of Section 111 of the Clean Air
Act. The proposed standards were published in the Federal Register
(47 FR 36859) with a request for public comment. A public hearing was
held on October 7, 1982. No comments were presented at the public
hearing. A total of 19 comments from industry, two trade associations,
the Oregon State Department of Environmental Quality, and a private
citizen were submitted during the comment period. Their comments and
EPA's responses are summarized in this document. The summary of comments
and responses serves as the basis for the revisions that have been made
to the proposed standards.
1.1 SUMMARY OF CHANGES SINCE PROPOSAL
In response to the public comments and as a result of EPA revaluation,
certain changes have been made in the proposed standards. Section 60.380
has been modified to clarify that at open-pit mines only crushers and
screens are affected facilities. Within the same section, an explicit
exemption from the standards has been added for conveyor belt transfer
points between crushers located in an open-pit mine and the concentrator,
mill, storage areas, or waste rock disposal areas. The definition of a
crusher in Section 60.381 has been modified to indicate that the crusher
includes the pan feeder, apron feeder or other conveyors located below
the crushing surfaces. This clarification is necessary (1) to distinguish
between transfer points between in-pit crushers and subsequent milling
operations, which are exempt, and crusher feeders, which are part of an
affected facility, and (2) to indicate that emissions from material
dropped from the crushing surfaces onto these feeders are intended to be
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controlled. Emissions from these feeders would be indistinguishable
from crushers and would be controlled simultaneously with the crusher
emissions.
The definition of "metallic mineral processing plant" has been
modified and a definition of "metallic mineral concentrate" has been
added in order to clarify what is meant by a metallic mineral processing
plant.
The list of ore-contact surfaces whose repairs are exempt from
reconstruction provisions (Section 60.15) has been expanded to include
surfaces on pan feeders. Pan feeders are located in high impact areas
and can be subject to a repair frequency similar to that of other ore
contact surfaces. A discussion of the rationale for exempting repairs
to ore contact surfaces is provided in the preamble to the proposed
standards (47 FR 36867).
Section 60.384 is expanded to clarify that the owner or operator of
a wet scrubber is required to record the scrubber liquid flow rate to
the scrubber and the change in pressure of the gas stream across the
scrubber during the initial performance test and at least weekly
thereafter. Reporting of the results of the initial performance tests
including these readings is required by the General Provisions. However,
semiannual reporting of subsequent readings is only required when one or
more weekly readings of the pressure difference or liquid flow rate
differs by more than ±30 percent from the readings of the most recent
performance test.
Section 60.385 (Test methods and procedures), is expanded to indicate
that Method 9, Visual Determination of the Opacity of Emissions from
Stationary Source (Appendix A, 40 CFR Part 60), is to be used for
determining opacity for stack and process fugitive emissions. This
section now directs the person observing opacity to take readings only
when emissions are clearly identified as emanating solely from the
affected facility being observed.
Method 9 has been amended to orovide additional instructions for
determining opacity from fugitive sources.
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1.2 SUMMARY OF THE IMPACTS OF THE PROMULGATED ACTION
1.2.1 Alternatives to the Promulgated Action
The alternative control techniques are discussed in Chapter 6 of
"Metallic Mineral Processing - Background Information for Proposed
Standards," EPA-450/3-81-009b, August 1982. (This document is also
referred to as the Background Information Document [BID].) These
regulatory alternatives reflect the different levels of emission control
from which one is selected that represents the best demonstrated
technology, considering costs, nonair quality health and environmental
and economic impacts for metallic mineral processing plants. These
alternatives remain the same.
1.2.2 Environmental Impacts of the Promulgated Action
The environmental impacts of the proposed standard are discussed in
Chapter 7 of the BID. A review of these environmental impacts indicated
no changes were necessary, and therefore, the impacts remain unchanged
since proposal. However, it should be noted that because metallic
mineral processing plants will operate under a variety of processing
conditions, the impacts of the proposed standard were analyzed in terms
of worst-case conditions that might be expected anywhere in the industry.
These worst-case conditions were then assumed for all affected facilities
in the industry. The result of these assumptions has been to overestimate
somewhat the environmental impacts, which is consistent with the
overestimate of control costs to ensure compliance under worst-case
conditions.
The review of the environmental impacts discussed in the proposal
BID constitutes the final Environmental Impact Statement.
1.2.3 Economic and Energy Impacts of the Promulgated Action
The economic impacts of the proposed standard are discussed in
Chapter 9 of the BID. A review of these economic impacts indicated no
changes were necessary, and therefore, the impacts remain unchanged
since proposal. As discussed in the previous section, the impacts of
the proposed standard were analyzed in terms of worst-case conditions.
These worst-case conditions were then assumed for all affected facilities
in the industry. Economic impacts were then calculated on the worst-case
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assumption that all facilities would require high-energy wet scrubbers
to meet the standards. The result of these assumptions has been to
overestimate the economic impacts.
The energy impacts of the proposed standards are discussed in
Chapter 7 of the BID and remain unchanged for the promulgated standards.
1.2.4 Other Considerations
1.2.4.1 Irreversible and Irretrievable Commitment of Resources.
This impact is discussed in Chapter 7 of the BID and remains unchanged
since proposal.
1.2.4.2 Environmental and Energy Impact of Delayed Standards.
This impact is discussed in Chapter 7 of the BID and remains unchanged
since proposal.
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2. SUMMARY OF PUBLIC COMMENTS
A list of commenters, their affiliations, and the EPA docket entry
number assigned to each comment are shown in Table 2-1. Twenty letters
commenting on the proposed standard and the Background Information
Document for the proposed standard were received. Significant comments
have been combined into the following seven categories:
2.1 General
2.2 Emission Control Technology
2.3 Modification and Reconstruction
2.4 Economic Impact
2.5 Environmental Impact
2.6 Energy Impact
2.7 Test Methods and Monitoring.
Comments, issues, and their responses are discussed in the following
sections of this chapter. Changes to the regulations are summarized in
Subsection 1.2 of Chapter I.
2.1 GENERAL
2.1.1 Comment: (IV-D-1) One commenter objected to the EPA's proposal
of emission limits based on the performance of control equipment under
so-called "worst-case11 conditions. He also felt that the EPA had not
established the standard at stringent enough levels to ensure that the
control device is operated and maintained as well as possible. This
commenter proposed that the EPA require that all new sources be controlled
at least as well as the average existing source employing "best techno-
logical systems." Based on EPA test data, this commenter stated that
the stack particulate mass concentration emission limit should remain at
0.05 g/dscm; but the stack emission opacity standard should be reduced
from 7 percent to zero percent opacity; and the process fugitive standard
should be reduced from 10 percent to 5 percent opacity.
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Response: In setting emission limits for a particular process or
group of processes under Section 111 of the Clean Air Act (CAA>, the EPA
must consider the range of operating conditions that would affect emissions
from these processes [National Lime Association v. EPA. 627 F.2d 416
(1980)]. Therefore, the EPA analyzed and tested numerous well-designed
and well-maintained facilities in the metallic mineral industry to
determine the most difficult control conditions and the emission limits
that could be achieved in these circumstances. In selecting control
devices for testing, the Agency consciously chose those devices that
were well-maintained and operated in accord with the General Provisions
[FR 60.11(d)] that require that owners and operators "maintain and
operate any affected facility including the associated air pollution
control equipment in a manner consistent with good air pollution control
practice for minimizing emissions." To base emission limits on the
average performance of a large sample of well-maintained control devices
as suggested by the commenter would likely render noncompliant those
control devices that operate under conditions more difficult than the
average. Therefore, the stack emission opacity standard and the process
fugitive emission standard will not be revised.
2.1.2 Comment: (IV-D-11, IV-D-18) Two commenters contended that mass
emission limits were based on the performance of high-energy wet scrubbers
that had not been "adequately demonstrated" as mandated in the Clean Air
Act. These commenters stated that high-energy wet scrubbers were not
currently in use at metallic mineral plants and therefore not available
for testing and that the Agency relied instead on the modeling of scrubber
performance to predict their operating characteristics. One of these
commenters (IV-D-11) also indicated her understanding that baghouses
were also not adequately demonstrated. Both commenters recommended that
the mass emission limit for these standards be revised and that a new
standard be based on the performance of low-energy wet scrubbers or
other "adequately demonstrated" technology.
Response: The EPA must demonstrate that a standard is achievable
over the range of conditions normally found in the industry, and therefore,
the performance of control options is analyzed in terms of worst-case
conditions. The basis for selecting worst-case conditions is discussed
below. Since high-energy wet scrubbers are not currently in use, the
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EPA used modeling to predict the performance of these scrubbers under
worst-case operating conditions. Primary evidence for the achievability
of the standard is derived from the EPA's test program of operating
control devices, including both baghouses and wet scrubbers.
The EPA tested a variety of control devices including baghouses and
wet scrubbers, primarily low pressure drop scrubbers, operating under a
variety of conditions. All baghouses and all but two of the wet scrubbers
tested in the mineral processing industry were able to meet the proposed
mass emission standard. Both of the scrubbers that exceeded the proposed
mass emission level were operating with relatively low pressure drops
(6 inches and 10 inches of water) and high mass loadings. The modeling
of scrubber performance using a predictive mathematical system indicated
that in both cases a 15-inch pressure drop scrubber could reduce emissions
from these sources to the proposed mass emission limits. The predictive
capability of this model has been widely demonstrated as discussed in
the document entitled Venturi Scrubber Performance Model (EPA-600/2-77-172).
In situations where there are no existing facilities controlled with the
best available control system, it is technically feasible and legally
permissible to use modeling techniques to project the system's performance.
The United States Court of Appeals for the District of Columbia Circuit
has specifically upheld the use of reasonable projections based on the
application of existing technology in other industrial settings when the
recommended technology is not currently in use at existing plants in the
industry being regulated under Section 111 [Portland Cement Association
v. Ruckelshaus. 486 F.2d 375 (1973)].
The EPA went one step further to demonstrate that the full range of
operating conditions possible in the industry were considered. A hypo-
thetical situation involving conditions of high uncontrolled emissions,
small particle size, and high moisture was developed. A baghouse that
had been tested under identical mass loading and particle size conditions
but with low moisture conditions, was able to meet the proposed standard.
However, high moisture conditions in the metallic minerals industry and
problems of moisture condensation affect the use of baghouses and may
require the use of wet scrubbers. Because these worst-case conditions
could not be exactly duplicated at currently operating facilities, it
was again necessary to simulate performance of a wet scrubber under such
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conditions using a mathematical model. This model demonstrated that a
30-inch pressure-drop wet scrubber, which is currently available for
installation at new plants, could reduce emissions under these hypothetical
worst-case conditions to the level of the mass emission standard. Such
worst-case conditions of high uncontrolled emissions, small particle
size, and high moisture appear as a very low probability occurrence
because high moisture conditions would lower uncontrolled emissions.
Nonetheless, the EPA considered these conditions in order to ensure that
the mass emission standards were demonstrated as achievable under the
full range of operating conditions,
Considering the range of test:; of wet scrubbers under actual operating
conditions and the modeling of wet scrubber performance under hypothetical
worst-case conditions, the EPA believes it has adequately demonstrated
the achievability of the mass emission standard proposed for the metallic
mineral processing industry based on the use of wet scrubbers. The EPA
has also shown that baghouses are also capable of meeting the standards
under most operating conditions found in the industry, although not
necessarily under worst-case conditions.
2.1.3 Comment: (IV-D-2) One comrienter indicated that the format of
the stack emission standard that requires continuous control of emissions
to a level of 0.05 grams per dry cubic meter deviates from the "Agency's
well-established practice of regulating averaged mass flows." The
commenter stated that the current form of the mass standard would cause
inequities in the industry such as allowing a facility that operates
8 hours per day only one-third the emissions of a facility operating
24 hours per day.
Response: Congress mandated in Section lll(a) of the Clean Air Act
that the Agency develop standards of performance for new stationary
sources that reflect "the degree of emission reduction achievable through
the application of the best system of continuous emission reduction
considering costs, non-air quality health and environmental impacts, and
energy requirements." In fulfilling the congressional intent, the
actual emission limitations formulated by the EPA can take one of several
forms. As discussed in the preamble to the proposed standard, often the
most equitable standards relate the allowable emissions to the amount of
material processed (i.e., pounds of emissions per pounds of material
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processed). As discussed in the proposal preamble (see Selection of
Format for the Proposed Standards), this type of format was not possible
for many types of facilities in this industry. Therefore, a concentration
format was chosen. For normal industry practice, however, a concentration
standard should generally relate the emissions to material processed.
For example, a small crusher would require a smaller control device with
a correspondingly lower air flow rate than a large crusher. Thus the
mass of controlled emissions emitted from the small crusher should be
less per unit of full-capacity operating time than that from the large
crusher. However, the actual emissions per ton of material processed
should be similar whether a company elects to have one large crusher
process a specified amount in an 8-hour day; or a smaller crusher process
the same amount in 24 hours.
The argument might be made that a company could circumvent this
standard either by placing an oversized, high-flow rate control device
on a facility or by running a facility significantly under capacity.
However, the capital, operating, and maintenance costs of such an approach
would very likely preclude extensive use of this strategy. More
importantly, such a circumvention of the standard would be a violation
of the General Provisions (40 CFR 60.12). Therefore, in the Administrator's
judgement, the concentration standard format is equitable and within the
intent of the Clean Air Act.
2.1.4 Comment: (IV-D-8, IV-D-9, IV-D-10, IV-Q-18) Several commenters
expressed concern about potential problems and inconsistencies in the
definition of "metallic mineral processing plants" presented in the
proposal preamble and regulation. They believe that the definition as
presented in the regulation might be interpreted to include primary
aluminum reduction plants under these standards, even though a separate
standard has been developed for reduction plants. They also believe
that the use of the term "aluminum plant" instead of the term "alumina
plant" in the preamble may also cause confusion. Two commenters also
suggested that the definition of metallic mineral plants be clarified to
indicate what portions of integrated ore process/smelting operations are
covered by the standards.
Response: As a result of these comments, the definition of "metallic
mineral processing plants" has been revised. The standard is intended
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to cover the production of alumina (aluminum oxide) from bauxite but not
the subsequent reduction of alumina to aluminum; therefore, the definition
has been modified to delineate the beginning and end of metallic mineral
processing. For the purpose of these standards, metallic mineral processing
includes all operations up to and including the final loading of
concentrates for shipment to off-site refining and smelting operations.
Where the concentration and refining operations are located at one site,
as in an integrated facility, metallic mineral processing includes all
storage and transfer operations up to the refining operations that
produce purified metals from concentrates.
For further clarification, a separate definition of "metallic
mineral concentrate" has also been added. This definition clarifies the
fact that concentrates are usually intermediate product;; between the
mining of ore and the production of refined metals. Metallic mineral
concentrates require additional processing to produce refined metals
although this additional refining to pure metals is not always performed.
For example, alumina may be used as a refractory and in other chemical
production processes or titanium dioxide can be used in the production
of paint. Although these concentrates are not refined to pure metals,
their production is still covered by the standard.
2.1.5 Comment: (IV-D-12, IV-D-18) Two commenters noted that the
preamble indicates that the loading and hauling of ore in the mine is
exempted from the standards but that truck loading and rail car loading
stations are listed as affected facilities in the regulation. These
commenters recommended that changes in the regulation be made to eliminate
inconsistencies and to indicate that loading of ore in the mine is not
covered by the standards.
Response: The EPA exempted the loading of material onto trucks and
railcars by mobile equipment such as front-end loaders or shovels at the
mine site because of the limited demonstration of the effectiveness of
specific control techniques for these sources for the variety of conditions
experienced across the country. Section 60.380 now specifically states
that only crushers and screens are considered to be affected facilities
in open-pit mines.
2.1.6 Comment: (IV-D-10, IV-D-18) Two commenters noted that the
preamble to the proposed regulation discussed several types of facilities
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or operations that are located within the bounds of a metallic mineral
plant but are not covered by the proposed standards. These commenters
requested that the EPA explicitly list in the regulation those facilities
not covered by the standards.
Response: In the preamble to the proposed regulations (47 FR 36861),
the EPA discussed the rationale for exempting from the proposed standards
certain major operations or facilities at metallic mineral processing
plants. This discussion is intended to provide for the public the
background information and support for the decisions on the coverage or
non-coverage of major facilities at metallic mineral processing plants.
In the regulation (40 CFR 60.380), the Agency provides a legal
designation of those metallic mineral processing facilities that are
"affected" by the regulation. The Agency also provides a specific
definition of the circumstances under which a facility listed as "affected"
would not be covered by the regulations (e.g., when they are located in
underground mines). The EPA does not provide a list of "non-affected"
facilities in the regulation because question would arise as to the
legal standing of metallic mineral facilities or operations that were
not specifically listed as either "affected" or "non-affected."
2.1.7 Comment: (IV-D-2, IV-D-18) Two commenters felt that the stack
opacity standard was redundant with the stack mass emission standard and
could be eliminated.
Response: Opacity limits are used in conjunction with mass emission
limits to ensure proper operation and maintenance of control equipment,
to lower compliance costs, and to simplify enforcement procedures.
Effective enforcement includes initial demonstration of compliance and
routine evaluation of control equipment operation and maintenance.
Compliance with particulate mass emission limits can only be demonstrated
with EPA Method 5 performance tests. However, Method 5 tests may be too
expensive and time consuming to be used routinely to monitor for the
proper operation and maintenance of emission control equipment, which is
the key factor in continuous compliance with the emission limit. In
contrast, EPA Method 9 opacity tests are quicker, simpler, and less
expensive than EPA Method 5. Therefore, opacity limits have been adopted
in the standards as an effective tool to assure proper operation and
maintenance of control equipment (Clean Air Act, Section 302(k)). The
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opacity limits have been set at levels no more restrictive than the
participate mass emission limits to ensure that any observed violations
of the opacity standards accurately indicate a violation of the participate
mass emission limits. In addition, the United States Court of Appeals
for the District of Columbia Circuit has specifically upheld the use of
opacity standards as a means of assuring control of mass emissions under
NSPS in Portland Cement Association v. Train, 513 F.2d 506, 508 (1975).
2.1.8 Comment: (IV-D-2, IV-D-18, IV-D-19) A number of commenters
objected to a process fugitive standard. One of these commenters (IV-D-19)
felt that it had not been justified in terms of its air quality benefits.
Two other commenters (IV-D-2 and IV-D-18) stated that the lack of difference
between a 10 percent process fugitive emission standard and a 7 percent
stack standard seemed to imply that EPA was requiring uncontrolled
emissions to be as low as controlled emissions from a stack. One commenter
(IV-D-19) noted that EPA data showed that all facilities tested were
meeting the process fugitive standard and that there is no reason to
expect that practices would change. This commenter felt that the additional
monitoring, performance tests, and recordkeeping resulting from the
standard were not justified in view of the insignificance of the emissions.
Therefore, he felt the standard can be eliminated. On the other hand,
one commenter (IV-D-18) stated that the standard should be raised from
10 to 20 percent opacity.
Response: The process fugitive emission standard serves at least
two purposes. First the standard ensures that emissions from facilities
that use control devices such as wet scrubbers or baghouses are in fact
collecting these emissions at the point of generation and ducting them
to the control device. Demonstrations of control device efficiency in
meeting the stack emission standard would do little good if emissions
were not being properly ducted to the device. Thus, where control
devices are used, the process fugitive emission standard is designed to
prevent short-circuiting of emissions and to ensure that the air quality
benefits that accrue to the control of stack emissions are achieved.
Second, the process fugitive emission standard allows the facility
to use alternative methods of emission control. For example, if the
operator of a facility can keep the process fugitive emissions below
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10 percent by using enclosures and/or wet suppression, then the operator
would not be required to duct emissions to a control device such as a
wet scrubber.
As noted by one commenter (IV-D-19) the EPA test data do indeed
demonstrate the achievability of the standard. Although the EPA's
experience shows that a poorly designed capture system could cause
emissions in excess of the standard, EPA test data show that properly
designed systems can meet the fugitive opacity standard of 10 percent.
In addition, as discussed above, eliminating the standard would make it
impossible to judge the effectiveness of alternative control systems
such as wet suppression.
While recordkeeping and reporting for initial performance testing
and periodic readings for the fugitive opacity standard are not required
by the metallic minerals NSPS, a separate notice requiring recording and
reporting of Method 9 opacity readings is being drafted for inclusion in
the General Provisions to 40 CFR Part 60. The ongoing costs of monitoring
and demonstrating compliance with the fugitive opacity standard increase
only marginally the total costs of performance testing and monitoring
for the entire metallic minerals NSPS.
For the above reasons, the Administrator has determined that the
process fugitive emission standard is necessary and justified.
2.1.9 Comment: (IV-D-2, IV-D-18) Two commenters felt that the 7 percent
stack opacity standard was unduly restrictive and that an opacity standard
of 20 percent (more commonly allowed by the States) should be set.
Response: Test data from 25 baghouses, 21 of which showed a maximum
of 0 percent opacity, demonstrates the achievability of the stack opacity
standard. The standard was set above the level of the highest 6-minute
average observed at a baghouse tested by the EPA. Therefore, the test
data indicate that the 7 percent stack opacity is appropriate.
2.1.10 Comment: (IV-D-2, IV-D-7, IV-D-15) One commenter questioned
the necessity for additional regulations for the metallic mineral
processing industry. The commenter felt that current regulatory standards
adequately protect the quality of the Nation's air, both in and around
metallic mineral processing plants. Another commenter stated that the
regulation was unnecessary because emissions from metallic mineral
processing are not suspended particles that adversely affect air quality
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but instead are coarse matter that falls to the ground within a short
distance of the source and, therefore, provide no hazard to health or
degradation of the environment. The commenter further stated that
emissions from new plants are controlled by Prevention of Significant
Deterioration (PSD), New Source Review (NSR), and Best Available Control
Technology (BACT) regulations, as well as State and local requirements
and asked the EPA to drop the NSPS due to insignificant benefits and
burdens. The third commenter suggested that the NSPS be delayed until a
new national ambient air quality standard (NAAQS) based on particle size
is established.
Response: The National Ambient Air Quality Standard for particulate
matter is 150 micrograms per cubic meter (ug/m3) calculated as a 24-hour
average concentration. The NAAQS allows this concentration to be exceeded
once per year. Although some fraction of the material emitted from
metallic mineral plants could be expected to fall out within the plant
boundary, dispersion modeling projections indicate that sufficient
material could be transported beyond the plant boundary to cause violations
of the NAAQS if no contols are applied. Dispersion modeling of metallic
minerals emissions allowed under current standards indicates that the
maximum 24-hour average concentration in the vicinity of processing
plants could range from 153 ug/m3 for small uranium plants to 1,007 ug/m3
for a large iron ore plant. These concentrations were all reduced to
below the NAAQS when emission levels were reduced to those allowed by
the NSPS.
Standards of performance are promulgated under Section 111 of the
Clean Air Act. Section lll(b)(l)(A) requires that the Administrator
establish standards of performance for categories of new, modified, or
reconstructed stationary sources that in the Administrator's judgment
cause or contribute significantly to air pollution that may reasonably
be anticipated to endanger public health or welfare. Standards of
performance prevent new air pollution problems from developing by requiring
application of the best technological system of continuous emission
reduction that the Administrator determines to be adequately demonstrated.
The 1977 Amendments to the Clean Air Act added the words, "in the
Administrator's judgment," and the words, "may reasonably be anticipated,"
to the statutory test. The legislative history for these changes stresses
two points:
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• The Act is preventive, and regulatory action should be taken
to prevent harm before it occurs; and
• The Administrator should consider the contribution of each
single class of sources to the cumulative impact of all
particulate matter emitters.
The 1977 Amendments to the Clean Air Act also required that the
Administrator promulgate a priority list of source categories for which
standards of performance are to be promulgated. The priority list,
40 CFR 60.16, was promulgated in the Federal Register August 21, 1979
(44 FR 49225). Development of the priority list was initiated by compiling
data on a large number of source categories from literature sources.
Major stationary source categories were then subjected to a priority
ranking procedure using the three criteria specified in Section lll(f)
of the Act. The procedure ranks source categories on a pollutant-by-
pollutant basis. In this ranking, first priority was given to the
quantity of emissions, second priority was given to the potential impact
on health or welfare, and third priority was given to the mobility and
competitive nature of the source category.
In light of the considerations stated above, the Administrator
found that the metallic mineral processing industry is a "significant
contributor." (Applying the criteria for prioritizing such contributors,
the Administrator ranked the metallic mineral processing industry 14th of
59 source categories on the priority list.) This listing decision
requires the Agency to promulgate standards of performance for new
sources in this category.
Standards of performance required by Section 111 play a unique role
under the Clean Air Act. The main purpose of standards of performance
is to require new sources, wherever located, to reduce emissions to the
level achievable by the best technological system of continuous emission
reduction considering the cost of achieving such emission reduction, any
nonair quality health and environmental impact, and energy requirements
[(Section lll(a)(l)]. Congress recognized that establishing such standards
would minimize increases in air pollution from new sources, thereby
improving air quality as the nation's industrial base is replaced over
the long-term. An NSPS thereby serves as a distinct means of achieving
the Act's goals, supplementing the role played by the Reasonably Available
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Control Technology (RACT) requirements for existing and new sources
within state implementation plans developed for the purpose of attaining
the NAAQS.
Where RACT-level control is already in place, however, the impact
of NSPS will be smaller than calculated. RACT and the systems chosen as
the best demonstrated technology for this industry's standards of
performance for new stationary sources are not conflicting types of
control; therefore, where RACT already applies, the standards of perfor-
mance will supplement RACT-level control. The EPA has determined that
existing RACT-level facilities that become subject to the standards of
performance (e.g., through modification) can achieve the additional
reduction required at a reasonable cost.
Congress also intended NSPS to play an integral role in the new
source review programs of the Act. Standards of performance required by
Section 111 also serve as the minimum level of emission control for BACT
and Lowest Achievable Emission Reduction (LAER), which are determined
case-by-case. Promulgation of these standards therefore assures that
BACT and LAER for individual sources are not less stringent than the
"best demonstrated technology" for the class of sources into which those
individual sources fall. Absent identification of "best demonstrated
technology" through promulgation of NSPS's, BACT and LAER might be less
stringent than BDT-level control.
Also, the standard has other benefits in addition to reducing
emissions beyond those levels required by current State regulations.
Standards of performance establish a degree of national uniformity,
which precludes situations in which some States may attract industries
by relaxing air pollution standards relative to other States. They
improve the efficiency of case-by-case determinations of BACT for
facilities located in attainment areas and LAER for facilities located
in nonattainment areas, by providing documentation and a starting point
for the basis of these determinations. This documentation results from
the process of developing a standard of performance, which involves
identification and comprehensive analysis of alternative emission control
technologies, development of associated costs, evaluation and verification
of applicable emission test methods, and identification of specific
emission limits achievable with alternate technologies.
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The existence of other environmental regulations was considered
during selection of BDT, but their existence does not lead the EPA to
conclude that standards reflecting better control technology cannot be
applied at reasonable costs.
The EPA is evaluating a possible change in the NAAQS for particulate
matter based on particle size considerations. However, the Clean Air
Act requires the timely promulgation of NSPS for priority industries and
does not allow for a delay in the promulgation of this NSPS. The impacts
of any changes in the particulate matter NAAQS on this NSPS and previously
promulgated NSPS for other industries will be handled in a similar
fashion. Until such changes are made to the NAAQS, this NSPS will be
based on the same assumption that guided the previous promulgation of
NSPS's for other particulate matter sources, namely that all suspended
particulate matter impacts human health and the environment.
2.1.11 Comment: (IV-D-7) One commenter noted, after listing all the
affected facilities covered by the proposed NSPS, that the standards
regulate every constituent of a new or modified metallic mineral processing
plant and, as such, are unnecessarily burdensome.
Response: In accordance with its congressional mandate to set
performance standards based on best systems of continuous emission
reduction considering cost, the EPA reviewed all operations associated
with the mining and processing of metallic minerals for possible coverage
by the NSPS. Certain of these operations and facilities are not covered
by the proposed standards for reasons of unavailability of adequately
demonstrated control systems or other technical complications. Those
facilities now listed as affected and covered by the proposed NSPS
represent those for which the EPA has adequately demonstrated control
techniques, which can be applied at reasonable cost.
As discussed in the proposal preamble, the choice of the affected
facility is based on the Agency's interpretation of Section 111 of the
Act and judicial construction of its meaning. (The most important case
is ASARCO, Inc. v. EPA. 578 F.2d 319 (D.C. Cir. 1978).) Under Section 111,
the NSPS must apply to "new sources;" "source" is defined as any building,
structure, facility, or installation which emits or may emit any air
pollutant" [Section lll(a)(3)]. Most industrial plants, however, consist
of numerous pieces or groups of equipment that emit air pollutants and
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that might be viewed as "sources." The EPA therefore uses the term
"affected facility" to designate the equipment, within a particular kind
of plant, which is chosen as the "source" covered by a given standard.
In choosing the affected facility, the Administrator must decide
which pieces or groups of equipment are the appropriate units for separate
emission standards in the particular industry. The Administrator must
do this by examining the situation in light of the terms and purpose of
Section 111. One major consideration in this examination is that the
use of a narrower definition results in bringing replacement equipment
under the standards sooner. If, for example, an entire plant is designated
as the affected facility and a piece of equipment is replaced, no part
of the plant would be covered by the standards unless the replacement
causes the plant as a whole to be "modified" or "reconstructed." The
plant as a whole could be considered modified only if the replacement
resulted in an increase in the aggregate emissions from the entire
plant. The plant as a whole could be considered reconstructed only if
the cost of the replacement exceeded 50 percent of the cost of an entire
new plant. If, on the other hand, each piece of equipment is designated
as the affected facility, then, as each piece is replaced, the replacement
piece will be a new source subject to the standards regardless of the
cost of the replacement or whether the replacement caused emissions from
the plant as a whole to increase. Since the purpose of Section 111 is
to minimize emissions by application of the best demonstrated control
technology (considering cost, health and environmental effects, and
energy requirements) at all new, modified, and reconstructed sources,
there is a presumption that a narrower designation of the affected
facility is proper. This presumption ensures that new emission sources
within the plant will be brought under the coverage of the standards as
they are installed; however, this presumption can be overcome if the
Agency concludes either that (1) a broader designation of the affected
facility would result in greater emissions reduction than would a narrow
designation or (2) other relevant statutory factors (technical feasibility,
cost, energy, and other environmental impacts) point to a broader
designation.
2.1.12 Comment: (IV-D-6) One commenter requested that an exemption
from the proposed standards be granted for very small (2 or 3 man)
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operations that might otherwise be forced out of business by the
regulations.
Response: Further questioning of the commenter revealed no examples
of processing plants of the size mentioned, and none are known to exist
(docket item IV-E-3). Therefore, the EPA can find no basis for
establishing such an exemption at this time.
2.1.13 Comment: (IV-D-19) One commenter requested that small pieces
of equipment be exempted from the stack mass emission standards because
of their relatively minor air quality impacts. Such an exemption could
be phrased in terms of air flow rate through the control device or
process throughput rate. The EPA requested more evidence from this
commenter that would indicate that an exemption was warranted on technical
or economic grounds (docket item IV-E-5). The commenter indicated that
he felt that an air flow rate of 1000 to 2000 cubic feet per minute
would be an appropriate cutoff because of the insignificance of emissions
from such devices. The commenter also indicated his understanding that
it was common practice for the EPA to set size criteria within a specific
industry below which an NSPS would not apply.
Response: In developing standards of performance the EPA is mandated
under Section 111 of the Clean Air Act to develop standards that reflect
the degree of emission limitation achievable through application of the
best technological systems of continuous emission (taking into considera-
tion cost, nonair health and environmental impacts, and energy
requirements). Where appropriate, the EPA has promulgated separate
requirements for certain subcategories of industrial source categories.
These subcategories may be defined by various criteria including size of
operation and type of material processed. Typically, this need for
special consideration arises from one of several causes. For example,
there may be economies of scale apparent within an industry that would
cause a standard applied across the industry to have disproportionately
adverse economic impacts on small facilities. Also, there may be reasons
of technical feasbility that would result in certain segments of an
industry being regulated differently or exempted from coverage. Such
decisions are made for specific reasons on a case-by-case basis.
In analyzing the technical and economic impacts of the proposed
standard for the metallic mineral industry, the EPA could find no reasons
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to exempt affected facilities below a certain size limit. Since the
commenter indicates that the process equipment would already have a
control device affixed to it, technical feasibility is not an issue.
Likewise the major cost of meeting the standard is the application of a
control device. Based on the EPA1;; analysis of both large and small
model plants of various configurations, this cost of control equipment
is reasonable. The incremental cost of an initial performance test and
the minimal recordkeeping required by these standards will not have a
significant economic impact on these operations. Thus, the EPA has
proposed that these standards cover all affected facilities regardless
of size.
2.1.14 Comment: (IV-D-10) One commenter recommended that experimental
testing of equipment not be covered by the NSPS. Further questioning of
the commenter indicated that he was concerned about the application of
the NSPS during the initial startup phases of an operation (docket
item IV-B-6).
Response: The General Provisions (40 CFR 60.8) provide that:
"Within 60 days after achieving the maximum production rate at which the
affected facility will be operated, but not later than 180 days after
initial startup of such facility..., the owner or operator of such
facility shall conduct performance test(s) and furnish the Administrator
a written report of the results of such performance test(s)." Experimental
testing or "debugging" of new equipment of the type referred to by this
commenter could be performed within this timeframe.
2.2 EMISSION CONTROL TECHNOLOGY
2.2.1 Comment: (IV-D-18) One commenter interpreted the EPA's discussion
of high pressure drop wet scrubbers as a recommendation that this device
be considered the preferred control method for the industry. This
commenter was also concerned that such a recommendation would require a
new facility in areas subject to Prevention of Significant Deterioration
Provisions to install high-energy scrubbers as the Best Available Control
Technology.
Response: The EPA does not necessarily recommend the use of a high
pressure drop scrubber or any other emission control technology to
attain and maintain compliance with the performance requirements of this
standard. Compliance with the pollutant concentration limits of this
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standard can generally be achieved by application of one of many
alternative emission control strategies, and, for a specific case, the
EPA does not require that a particular control device be used.
The determination of Best Available Control Technology for sources
subject to Prevention of Significant Deterioration provisions results
from a case-by-case analysis considering economic, energy, and environ-
mental factors. As defined in 40 CFR 52.21(b)(12) "Best available
control technology means an emissions limitation (including a visible
emission standard) based on the maximum degree of reduction for each
pollutant subject to regulation under the Act....which the Administrator,
on a case-by-case basis, taking into account energy, environmental, and
economic impacts and other cost, determines is achievable..."(emphasis
added). Embodied in this definition is the emissions limitation criteria
for the determination of BACT. Site-specific factors, while considered
in establishing BACT, are not considered in the NSPS process, and,
therefore, the PSD review authority has some degree of flexibility in
determining BACT. In no case can the BACT emission limitation be any
less stringent than an applicable NSPS. Once the numerical value is
established any control technology can be used by the plant to achieve
the emission limit provided no other adverse environmental impacts
result from its use. However, in actual practice, the PSD reviewing
authority must exercise judgment in approving the use of a particular
control device to ensure that the device is appropriate, is sufficiently
reliable, and will not adversely affect other environmental factors for
the particular case.
As the analysis of the high-energy scrubber shows, there are extreme
case-specific factors that may require use of that technology to comply
with the NSPS. Furthermore, there may be other cases where a BACT
emission limitation more stringent than the NSPS emission limit may
require use of medium- or high-energy rather than low-energy scrubbers.
However, the PSD review authority must weigh the statutorily prescribed
factors in each case and arrive at the appropriate level of BACT.
2.2.2 Comment: (IV-D-11, IV-D-14) Two commenters discussed numerous
problems with the use of baghouses at metallic mineral plants. Commenters
noted that baghouses are subject to bag breakage, which requires
maintenance that exposes repair workers to high concentrations of dust.
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Breakage problems could also require the installation of dual baghouse
systems, the cost of which was not considered in the economic analyses.
The fire danger associated with maintenance welding around baghouses
will be higher than with wet scrubbers. Finally, the handling and
disposal of dust collected in baghouses can be a problem.
Response: The Agency's experience and a review of numerous industry
applications of baghouses at mineral processing facilities indicate
that, although the problems enumerated above can occasionally occur with
the use of baghouses, good maintenance practices with properly designed
baghouses will minimize their occurrence. The selection of the proper
baghouse fabric, air-to-cloth ratios, and baghouse configuration will
greatly reduce the frequency of bag breakage. The use of compartmentalized
baghouses will allow the isolation of a section of the baghouse for
maintenance while the rest of the baghouse is kept on-line. The use of
compartmentalized baghouses, whose costs were calculated for the standard,
will eliminate the need for dual systems.
Repair workers will require protection from exposure to high
concentrations of dust by techniques similar to those used in other high
exposure areas of metallic mineral plants. These techniques include the
use of respirators, proper ventilation, dust suppression and other
methods. Fire danger from welding sparks sucked into baghouses can be
eliminated by shutting down the section of the baghouse on which repair
is occurring and by other common safety measures.
Discussions with design engineers familiar with the metallic mineral
industry indicate that the methods used for disposing of collected dust
will vary with the location of the control device and can even influence
the selection of the type of control device for a particular facility.
If slurried material can be disposed easily, as to a wet beneficiation
system, then a wet scrubber may be the preferred control device. On the
other hand, where the collected particles are more readily disposed or
recycled in a dry state, as when they are comprised primarily of the
final concentrates, a baghouse may be preferred. The Agency has also
inspected several facilities in which materials collected in baghouses
are slurried and recycled to the beneficiation system.
The EPA does not deny the possibility of problems with baghouses or
any other types of control devices that are not properly designed for
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the control situation or are not properly maintained. Conversely, most
problems can be eliminated with proper design, installation, and
maintenance. Where these problems cannot be avoided, the standard
permits the use of alternative technology such as wet scrubbers.
The selection of a particular type of control device will depend on
a variety of factors including overall reliability in a specific situation.
The choice ultimately resides with the facility's personnel. As stated
in the preamble to the proposed standard, baghouses may be used to
achieve compliance with the standards; however, their use is not required.
2.2.3 Comment: (IV-D-13) One commenter calculated that wet scrubbers
at a metallic mineral plant can use from 0.5 to 1.5 million gallons of
water per day. The cost of treating this water should be recalculated
in view of the fact that industry data show that the cost of complete
recycle is 100 times higher than the Effluent Guidelines Division cost
provided in Chapter 8 of the BID.
Response: The commenter calculated the scrubber water usage of
0.5 to 1.5 million gallons of water per day on the assumption that
scrubbers use water once and then dispose of it (docket item IV-E-9).
This is not correct. Scrubbers are typically designed to recycle from
95 to 99 percent of their water internally. The slurry that is eventually
discharged is suitable for use in the beneficiation circuit of most
plants and is often piped to that part of the mill for use as process
water. Thus, typical plant-wide water usage increases that result from
the use of wet scrubbers are very small -- theoretically only evaporative,
pumping, and leakage losses. Even if the scrubber slurries were directly
discharged to the tailings treatment system their volume would represent
less than I percent of the expended process water.
The EPA's Effluent Guidelines Division reports that a relatively
unique configuration at one metallic mineral processing plant could
cause a great increase in the cost of complete recycle of total plant
process water, although this will not normally be the case (docket
item IV-B-5). Regardless of the actual cost of treating process effluents,
the disposal of wet scrubber slurries should have little impact on the
cost of treating process effluents because even under worst-case conditions
scrubber slurries would represent less than 1 percent of the process
effluents.
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2.2.4 Comment: (IV-D-15) One commenter objected to the use of non-
metallic industry data in evaluating control equipment performance in
metallic mineral industries. She noted that metallic ores are often
dissimilar to non-metallic ores, particularly in concentrate and byproduct
characteristics. This commenter also stated that, if the EPA used
non-metallic data, then the stack mass emission standard should be as
high as the stack standard for the coal preparation industry (0.04 gr/dscf).
Response: As discussed in Chapter 4 of the proposal BID and preamble,
emissions from metallic mineral processes and non-metallic processes are
very similar in terms of the crucial characteristics of mass loading and
particle size. Data from non-metallic plants were used in order to
further our understanding of the performance of control devices under
possible worst-case conditions. In addition to the fact that emissions
from metallic and non-metallic ores are similar, it should also be noted
that metallic ores are often comprised primarily of non-metallic minerals.
The material processed in the coal preparation industry and the
emissions from thermal dryers at the coal preparation plants differ in
several critical variables from the material and emissions at metallic
mineral plants. Emissions from coal preparation dryers are characterized
by high uncontrolled emission concentration (8-10 grains per standard
cubic foot and higher), small particle size (10-50 percent less than
1 micron), and low density (1.25-1.45 grams per cubic centimeter). As a
result, these emissions are more difficult to control than emissions
from metallic mineral facilities. Although high pressure drop scrubbers
are routinely used in the coal preparation industry, control efficiencies
cannot be routinely extrapolated to the metallic minerals industry
because of the difference in emission characteristics. For these reasons,
the stack mass emission standard for the metallic mineral industry is
different than the standard for the coal preparation industry.
2.2.5 Comment: (IV-D-14, IV-D-18) Two commenters suggested that
alternative control methods such as water sprays, dust suppressants,
covers, and enclosures should be considered in addition to traditional
capture and collection systems in developing the standards.
Response: These alternative control methods were not widely used
relative to other control devices in the metallic mineral industry
during the development of this standard, and therefore, the economic and
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environmental impacts of these alternatives were not specifically evaluated.
Moreover, studies of their use in the non-metallic industry indicate
that they do not achieve greater control than the traditional capture
and collection systems. However, the standards do not prohibit the use
of any alternative control method as long as it will meet the emission
limitation. The EPA has written the standard in a format that allows
the use of several control alternatives including wet suppression and
enclosures to meet the emission limitations. Although the costs of
these alternatives were not specifically enumerated, in some instances
these systems may be appropriately used at significantly lower costs
than traditional control devices. In line with the EPA's approach of
showing cost under worst-case conditions, the EPA used costs of more
traditional capture and control systems to determine economic impacts of
the proposed NSPS.
2.2.6 Comment: (IV-D-14) One commenter stated that it would be very
difficult to achieve the process fugitive emission standard at a reasonable
cost at ore dumps and conveyor belt transfer points in open-pit mines
and requested that the standard be withdrawn. This commenter provided
data on the cost to control fugitive emissions at ore dumps and conveyor
belt transfer points at in-pit crushing systems. This commenter stated
that the cost to control emissions at these facilities was high enough
to forestall a changeover to in-pit crushing and conveyorized transport.
This changeover was being considered at an existing mine as a means to
reduce energy and labor costs associated with truck hauling. The commenter
also noted that the use of in-pit crushing and conveyorized transport
would reduce plant fugitive emissions by 40 to 50 percent because truck
hauling would be reduced.
Response: Because these new in-pit crushing and conveying systems
were not in use during the development of the NSPS, the EPA has limited
information regarding the industry-wide impacts of the NSPS upon these
systems. Due to the lack of sufficient emission test data and data on
the cost and design of effective in-pit control systems, the EPA is
unable to identify the best demonstrated technology (BDT) for these
facilities at this time and is, therefore, excluding truck and railcar
unloading stations (ore dumps) and conveyor belt transfer points located
in open-pit mines and conveyor belt transfer points located in open-pit
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mines and conveyor belt transfer points located between the mine and the
mill, storage, or waste disposal areas from coverage under the NSPS for
metallic mineral processing at this time.
However, as a result of the comment, the EPA conducted an evaluation
of the impacts associated with the control of emissions from ore dumps
at in-pit crushing operations and from overland conveyor systems -at one
plant for which information was available. This evaluation was based on
the process information supplied by the commenter for an open-pit mining
operation that involves the excavation of greater than 100,000 tons of
ore and 150,000 tons of waste rock per day.
Potential emissions from these ore dumps and conveyor belt transfer
points at this plant are significant based on the number of facilities
and the amount of material transferred through these points. The EPA
calculated that the uncontrolled emissions from the ore dumps at the one
facility for which data were available would likely range from 2,000 to
6,000 tons per year. Uncontrolled emissions from conveyor belt transfer
points on overland conveyors could be in the range of 2,000 to 23,000 tons
per year depending on the actual ore and waste-rock moisture levels.
The cost to control the emissions from these ore dumps and conveyor
belt transfer points at this plant also appears significant. Although
the EPA believes that some of the costs provided by the commenter are
based on process designs that do not allow for the most economical use
of control equipment, even the EPA's calculations for less costly designs
indicate a potential economic impact on the production costs of copper
of as much as I percent from the control of emissions from these sources
alone.
The EPA notes, however, that the preliminary emission and cost
information gathered from this plant suggests that the impact of
controlling ore dumps and conveyor belt transfer points is potentially
so great as to delay or discourage decisions to replace truck hauling
systems with conveyor transport systems. This effect, if it were to
occur, would be counter-productive from an environmental standpoint.
The uncontrolled emissions from truck hauling are typically much greater
than uncontrolled emissions from conveyor belt systems. Viewed in the
broad perspective of controlling emissions from the transport of ore and
waste rock, the replacement of truck hauling with conveyor belts thus
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represents a very effective method for reducing emissions from the truck
transport of rock, emissions that otherwise in the past have proven
difficult to control. Thus, the EPA would seek to encourage this shift
in process technology from the use of truck hauling to conveyor transfer.
The EPA will review the development of this transport technology
and the impacts of possible control techniques for these facilities
during its periodic review of this NSPS.
2.2.7 Comment: (IV-D-4) One commenter indicated that the impacts of
these standards on new portable in-pit crusher and conveyor systems were
not analyzed. At least one company has constructed a portable crusher
for use in open-pit mines. Although not a self-powered mobile facility,
this crusher is designed to be moved by heavy equipment on an annual or
semi-annual basis as operations shift in the mine. Crushed ore is then
transported by conveyor belt from the mine to the mill. This commenter
noted that such a system of in-pit crushing and conveying of ore could
reduce the fugitive emissions associated with the truck transport of ore
over dirt roads because the system would reduce the number of trucks
needed. An exemption from coverage by these standards was requested for
portable crusher and conveyor systems in open-pit mines because analysis
of the environmental, energy, and economic impacts was not performed for
these facilities.
Response: The EPA requested from the company more information that
would indicate that the economic, environmental, and energy impacts of
these standards on portable crusher and conveyor systems would differ
from impacts on fixed-site crusher and conveyor systems (docket
item IV-E-4). Information received to date does not indicate a significant
difference in the techniques used to control emissions from portable and
stationary crushers. Likewise the technology used to unitize and transport
the crusher and conveyor system can quite readily be extended to the
control devices. In discussions with EPA representatives, this commenter
indicated that a portable crusher under construction during proposal of
this standard would use a charged droplet electrostatic precipitation to
meet State standards. The EPA concludes that the cost to control emissions
from portable and stationary crushers would be similar and therefore
reasonable. Therefore, the Administrator believes that an exemption for
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these portable crushers is not warranted. However, as discussed in the
response to comment 2.2.6 above, conveyor belt transfer points between
in-pit crushers and subsequent milling or waste rock disposal areas are
exempted from the NSPS.
2.2.8 Comment: (IV-D-13) One commenter recommended that the EPA
delete the standard for process fugitive emissions until such time that
methods are developed to control the point source of process fugitive
emissions. This commenter specifically cited the example of the coarse
ore reclaimed from a stockpile. He claimed that process fugitive emissions
from the reclaim operation would be difficult to distinguish from the
open-source fugitive emissions from the stockpile itself.
Response: As discussed in the proposal BID and preamble, the EPA
tested all types of affected facilities covered by this NSPS to determine
the proper methods for reducing or eliminating process fugitive emissions
and the levels to which these emissions could be controlled. The process
fugitive emission standards are based on tests of properly designed and
maintained hoods, enclosures, and air ducting systems. The EPA tests of
ore reclaim operations showed that properly designed enclosures and
hoods satisfactorily captured all process fugitive emissions. In addition,
because ore reclaim operations would be located in tunnels or recessed
areas beneath the stockpile, open-source fugitive emissions from the
stockpile would not interfere with the determination of emissions from
the reclaim operation.
Because the achievability of the process fugitive standard has been
adequately demonstrated for the facilities now covered by this NSPS, the
EPA will not delete this standard.
2.2.9 Comment: (IV-D-17) One commenter indicated that the opacity
standard for process fugitive emissions may be difficult to achieve in
arid areas where fairly strong winds are common and the individual
process units are not located in an enclosed area. The commenter suggested
that the final rulemaking consider these situations.
Response: The EPA tested many process units under windy conditions.
Such windy conditions will require enclosures at the emission sources.
Such enclosures need not encompass the entire piece of process equipment;
rather they can be limited to the area at which emissions could escape
to the open air. The efficient use of enclosures is common in the
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industry and greatly reduces the air flow requirements at emission
sources. EPA tests indicate that the efficient use of enclosures will
greatly facilitate the achievability of the process fugitive emission
standard even under windy and arid conditions.
2.2.10 Comment: (IV-D-2) One commenter stated the emissions from a
wet scrubber planned for installation at a new facility were estimated
to be 0.093 g/Nm3 using vendor information and uncontrolled emission
factors from the EPA's Compilation of Air Pollutant Emission
Factors (AP-42) and State reference material. This estimated emission
rate would exceed the stack emission standard set by this NSPS.
Response: This commenter was contacted to obtain more information
on the basis for this controlled emission estimate (docket item IV-E-8).
The commenter stated that the uncontrolled emissions were assumed to be
approximately 12 grains/standard cubic foot (scf) based on their
interpretation of emission factors provided in the EPA document AP-42.
The EPA representative pointed out that the AP-42 factors used by the
commenter have been revised recently by the EPA to specify emissions by
ore moisture conditions and that their estimates of uncontrolled emission
rates are very high for any conditions at crushing and material transfer
operations. In addition, EPA testing at an existing facility at the
same location as the planned facility showed uncontrolled emissions of
less than 1 grain/scf. Therefore, considering a more reasonable estimate
of uncontrolled emissions and their scrubber vendor guarantee of
99.7 percent removal efficiency, it is reasonable to believe that the
stack emission standard can be achieved.
2.3 MODIFICATION AND RECONSTRUCTION
2.3.1 Comment: (IV-D-14) Citing the ASARCO and the Alabama Power
decisions, one commenter stated that the entire reconstruction provision
is unlawful and should be deleted. This commenter interpreted the Clean
Air Act (Section lll(a)(4)) to indicate that the NSPS should only apply
to modifications to existing facilities that cause an increase in emissions.
Response: Since in enacting Section 111 Congress did not define
the term "construction," the question arose whether NSPS would apply to
facilities being rebuilt. Noncoverage of such facilities would have
produced the incongruity that NSPS would apply to completely new facilities
but not to facilities that were essentially new because they had undergone
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reconstruction of much of their component equipment. This would have
undermined Congress1 intent under Section 111 to require strict control
of emissions as the Nation's industrial base is replaced.
EPA promulgated the reconstruction provisions in 1975, after notice
and opportunity for public comment (40 FR 58420, December 16, 1975), to
fulfill this intent of Congress. Since this turnover in the industrial
base may occur independently of whether emissions from the rebuilt
sources have increased, the reconstruction provisions do not focus on
whether the changes that render a source essentially new also result in
increased emissions.
Congress did not attempt to overrule EPA's previous promulgation of
Section 60.15 in passing the Clean Air Act Amendments of 1977. This
indicates that Congress viewed the reconstruction provisions' focus on
component replacement, rather than emissions level, as consistent with
Section 111. See, e.g., Red Lion Broadcasting Co. v. FCC. 395 U.S. 367
(1969); NLRB v. Bell Aerospace Division, 416 U.S. 267 (1974). Nor has
any Court questioned the Agency's authority to subject reconstructed
sources to new source performance standards.
As the commenter correctly notes, the Court of Appeals for the D.C.
Circuit, in ASARCO v. EPA, 578 F.2d 319, 327 n.24 (D.C. Cir. 1978),
stated that:
The Act's language ... is aimed at new sources, not just
new construction, and defines existing sources that are altered
so that their emissions increase as new sources.
Id. (Emphasis in original.)
Contrary to the commenter's contention, however, this passage, as well
as the passage the commenter quoted from the first Alabama Power decision,
Alabama Power Co. v. Costle, 606 F.2d 1068, 1081 (D.C. Cir. 1979),
indicates merely that Section 111 defines existing sources with increased
emissions as "modified" sources subject to "new source" performance
standards. Those passages do not mean, either explicitly or by
implication, that existing sources undergoing such extensive component
replacement that they are essentially newly constructed should not be
considered newly "constructed" sources made subject to "new source"
performance standards through Section lll(a)(2). To the contrary, in
ASARCO the Court implicitly approved the EPA's treatment of these
reconstructed sources as "new sources" subject to NSPS. (ASARCO, 578 F.2d
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at 328 n.31) In fact, the Court suggested in that case that the
reconstruction provisions may not go far enough toward preventing possible
abuses by owners seeking to avoid NSPS by perpetuating the useful lives
of their existing facilities indefinitely through gradual component
replacement.
The commenter also claims incorrectly that the D.C. Circuit's
opinions in the first and second Alabama Power Co. v. Costle decisions,
supra and 636 F.2d 323, 401 (D.C. Cir. 1979), preclude the EPA from
finding reconstructed sources to be "new sources" subject to NSPS when
their emissions have not increased. In the excerpt quoted by the
commenter, the Court was addressing the issue of whether, for purposes
of deciding the applicability of the prevention of significant deterio-
ration (PSD) provisions to an existing facility, a change increasing
emissions from one part of the plant would subject that narrow set of
equipment to the PSD review process as a "modification", even when
overall plant emissions had not increased. The Court upheld the EPA's
decision not to find this type of change to be a "modification", relying
primarily on the following reasoning:
According to their stated purposes, the PSD provisions seek to
assure that any decision to permit increased air pollution
in any area to which this section applies is made only after
careful evaluation of all the consequences of such a decision
and after adequate procedural opportunities for informed
public participation in the decisionmaking process. Congress
wished to apply the permit process, then, only where industrial
changes might increase pollution in an area, . . .
Jji. (Emphasis in original.)
For two reasons, this reasoning and, therefore, the Alabama Power
rulings do not undermine the Agency's authority to subject reconstructed
source to NSPS when emissions from the source have not increased.
First, in contrast to the purposes of the PSD program, the primary
purpose of the NSPS program is not to control emissions to produce a
particular ambient effect in a particular area. Rather, its purpose is
to effect a gradual reduction in emissions as the nation's industrial
base is replaced. For the reasons described above, this goal is furthered
by applying NSPS to any equipment that has undergone substantial component
replacement, regardless of the level of emissions before and after the
change. Second, the Court in Alabama Power was not addressing the NSPS
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reconstruction provisions; it construed the definition of "modification",
merely for PSD purposes. As described above, when the Court did address
the reconstruction provisions in the NSPS area — in the ASARCO footnote
cited above -- it did not question their validity, but instead implicitly
upheld them when it suggested that those provisions do not go far enough
to serve the goals of Section 111.
2.3.2 Comment: (IV-D-10) One commenter noted that under the proposed
standards any new or substantially rebuilt piece of equipment would
become subject to the proposed emission and opacity limits. This commenter
noted that if one of several units that are vented to a common emission
control device should be replaced or substantially rebuilt, the replacement
equipment would fall under the standards as a new source while other
similar units would remain unaffected. The commenter questioned whether
the EPA would require a separate emission control system for the one
unit that was already part of an overall control system. This commenter
recommended that a plant have the option of incorporating the emissions
from the replacement unit into the general control system provided the
plant reduces the overall emissions by an amount equal to that amount
that would have been reduced had the affected unit been a separate
system and had the NSPS applied to it.
Response: The commenter is correct that an affected facility that
is new (in this case, a replacement) or is substantially rebuilt, would
be subject to the standards. The owner would have two alternative means
through which compliance could be achieved. One would be to install a
separate control device. The other would be to upgrade the existing
control device such that if the new or replacement facility were ducted
to the common control device, the total emissions conform to the standard.
The effect of these is consistent with the intent of Section 111 of the
CAA, which is to cause new air pollution sources to install BDT.
The alternative of ducting the emissions from new facilities into
existing technology that is less effective than BDT, would not result in
the emission reductions and attendant air quality benefits envisioned by
Section 111. The alternative presented by the commenter would involve
obtaining emission reduction credits from an existing facility to offset
the amount by which the new facility exceeds the level attainable with
BDT. This is not appropriate for several reasons. First, this is
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inconsistent with the primary purpose of Section 111, which is to reduce
emissions to a minimum through the use of BDT. In addition, this
alternative creates a number of enforcement uncertainties, one of which
is the question of what would happen if the new facility has a longer
life than the facility from which the emission reduction credits were
obtained. Moreover, implementation of such an approach would require
(1) precise pre-construction information on expected actual emission
rates and (2) assumptions about the future relative inputs of the multiple
units to the common control device. In the first instance, although it
is presumed that the facilities in question would be meeting State
standards, inherent variability in performance of the control device
would make it difficult to pick a baseline emission level against which
to measure improvement. This variability would make it very difficult
to differentiate between actual emission reductions and calculated
reductions that may or may not actually occur. In the second instance,
where several different types of equipment were ducted in common, it
would be difficult not only to apportion emissions among them as a base
for determining reduction but to assess the long-term constancy of that
apportionment once it is made. Indeed, if a baghouse were used, the
application under such an arrangement of an opacity limit capable of
assuring the BDT emission reduction, would be infeasible.
2.3.3 Comment: (IV-D-13) One commenter was concerned about the
reconstruction provisions of the regulation. He stated that maintenance
activities for ore contact surfaces on dust collection ductwork, chute
liners, vents, and pans on pan feeders should be exempted from the
reconstruction provisions and that the definition of facilities whose
repairs and replacements are exempted from reconstruction consideration
should be expanded to include: "all surfaces subject to abrasion by
direct contact with ore." This commenter also requested that catastrophic
repair be exempted from the reconstruction provisions. For example, a
large piece of metal jammed in a crusher can cause severe damage to the
crusher, its motor, electrical components, etc. Repair of this facility
is unplanned and not intended to upgrade and modify equipment or technology,
and the commenter felt it would be unreasonable to classify such equipment
as reconstructed and subject to the NSPS.
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Response: The reconstruction provisions apply only to those
facilities listed as affected facilities in the regulation. Dust
collection ductwork, vents, and chute liners are not listed as affected
facilities. In addition, it should be noted that dust collection ductwork
and vents would be considered part of the emission control system, whose
repair or replacement is exempt from the reconstruction regulation as
well as exempt from the modification provision, 40 CFR 60.14, so long as
these actions do not result in an increase in emissions. Pan feeders
are defined as part of the crusher affected facility under Section 60.381.
Because the ore contact surfaces on feeders could be subject to the same
repair frequency as other ore contact surfaces, the definition of ore
contact surface is expanded to include pan feeders. A general exemption
for all ore contact surfaces is not included because of the inherent
difficulty in applying such general language, that is, a general exemption
would be too ambiguous.
Repairs to a facility that occur as a result of an unplanned or
catastrophic occurrence are not exempted from reconstruction considera-
tions unless they are covered under the ore contact surface exemptions.
The reconstruction provisions apply in a straight-forward manner to any
existing facility undergoing substantial component replacement. Neither
the language nor the purpose of either Section 60.15 nor the definition
of "new source" in Section 111 supports an exemption based on the owner's
reasons for replacing the facility component.
2.4 ECONOMIC IMPACTS
2.4.1 Comment: (IV-D-7, IV-D-8, IV-0-9, IV-D-11, IV-D-18) A number of
commenters discussed various aspects of the economic impacts of the
proposed standards. One commenter (IV-D-7) stated that the proposed
standards have lost sight of the primary purpose of the Clean Air Act,
which is to promote "the public health and welfare and the productive
capacity of its population." This commenter questioned the necessity of
additional regulation of an indus;try that is struggling under the
competition of the world market. Four commenters (IV-D-8, IV-D-9,
IV-D-11, IV-D-18) noted that the economic analyses were performed with
1979 cost and price data that are out of date. Production prices have
risen since then while in many cases product prices have fallen. For
example, one commenter noted that cost of producing copper increased
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44 percent from 1978 to 1981. The cost of copper, on the other hand,
fell from a dollar per pound in 1979 to 65$ to 75$ per pound in 1982.
The impact of these standards would be correspondingly more severe at
these lower prices. An increase in price cannot be passed on because of
world-wide competition in the copper market. A similar situation was
presented for the aluminum industry. These commenters generally requested
that the economic impacts of the standards be reevaluated in light of
the weaker economic conditions of the industry today.
Response: The Agency recognizes that since the original economic
analyses were performed in developing these standards many segments of
the metallic mineral processing industry have experienced severe economic
disruptions. The demand for many metals has fallen significantly with a
corresponding drop in price. Even at the price figures quoted in 1979
and 1980 for some metals it was questionable that new processing plants
could be profitably built unless there was a reasonable prospect for an
increase in demand and price. Nonetheless, the Agency believes that,
because of the central role the metallic mineral processing industry
plays in the American economy, the long term prospects for growth in the
industry are good. This belief is obviously shared by others outside
the government as the acquisition of several metallic mineral and metal
processing firms by still larger natural resource-based companies would
attest.
Long-term optimism does not completely redress the short-term
difficulties in the industry, yet it is this severe drop in the demand
and price for metals - and not environmental regulations - that makes
the new construction unlikely at present. When the demand for metals
increases with a corresponding increase in price to levels more comparable
to 1979 prices (in constant dollars), then new construction will be more
likely. Thus, it is reasonable to calculate the impact of these standards
for new facilities by using the price of the commodity that is a minimum
requisite for the construction of a new facility.
The EPA recognizes that the costs of constructing a new metallic
mineral processing plant have likely increased in the past several
years. The cost of control equipment has also increased in a proportionate
manner. Thus, the costs of control equipment as a percentage of processing
equipment cost remained relatively constant. A large manufacturer of
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crushers has quoted price increase;; of 21 to 24 percent between
January 1, 1980, and January 1, 1983 (docket item IV-E-6). During the
same period, a manufacturer of control devices has quoted price increases
of 20 to 22 percent for multi-vane and venturi wet scrubbers (docket
item IV-E-7). At the point at which the rise in the price of metals
makes it reasonable to invest in new plants, the cost of meeting the
standards will have the same relatively insignificant impacts shown in
the analyses based on 1979 dollars.
In addition, the possible economic impacts of the proposed standards
are based on several assumptions that tend to exaggerate the impacts,
particularly at copper plants. As noted elsewhere in these responses,
the economic analysis assumes the universal use of high-energy scrubbers
when in fact less costly low-energy scrubbers or baghouses can meet the
standards at many locations. In addition the concentration of copper in
ore at small copper mines was assumed to be 0.45 percent. This figure
is more typical of large deposits of larger copper mines, which, because
of their economics of scale, can operate at these lower concentrations.
One recently expanded mine and mill in Arizona has the capacity to
process about 1,700 tons per hour of ore containing 0.49 percent copper
and 0.02 percent molybdenum. On the other hand, smaller copper facilities
require higher mineral concentrations. New information developed since
the original economic analyses were performed indicates that a facility
in the planning stage in New Mexico would process about 100 tons of ore
per hour containing about 2 percent copper and 3 percent zinc instead of
the 0.45 percent copper concentration assumed in the economic analysis
for small copper plants. With a higher copper concentration and the
consequent higher production of concentrates and the concurrent processing
of by-products, the impact of the proposed standards on the production
price of metals would be greatly reduced at these smaller plants. Even
assuming the universal use of high-energy scrubbers, the economic impact
of the standards on copper prices at this planned plant in New Mexico
would be closer to 0.17 percent than the 1.7 percent figure quoted for
150 ton per hour copper plants in preamble and the BID for the proposed
standards.
The EPA is very sensitive to the possible adverse economic impacts
of the NSPS. For that reason, the Agency has examined very carefully
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the capital costs of controls, the ability of firms to finance these
costs, the potential price increases, and the cost per ton of emissions
reduced, which addresses the issue of control costs relative to other
industries. As discussed in the proposal preamble, none of these projected
impacts appear unreasonable. More specifically, with the one exception
discussed above, the projected price increases were all less than 1 percent
and typically less than 0.5 percent. In balancing the protection of
public health and welfare against the productive capacity of this industry,
these costs appear reasonable and, in fact, are small compared to other
factors that affect costs and prices.
The EPA has been extremely conservative in calculating the economic
impacts of the proposed standards. As demonstrated by our original
analyses and the discussion above, the proposed standards will not deter
new construction when the demand for metals provides the economic
conditions conducive to the development of new plants. Therefore, an
extensive revaluation of the economic impacts of the standards is
unnecessary.
2.4.2 Comment: (IV-D-18) One commenter stated that the discussion of
costs in the proposal BID (Chapter 8) based on the use of building
evacuation techniques at lead smelters to comply with the lead NAAQS,
should be revised because the technique is unworkable. The commenter
cited a case in which building evacuation caused other problems.
Response: Section 8.2 of the proposal BID is provided to alert the
public to the other regulatory costs affecting the industry in addition
to those resulting from the proposed standards. The cost data provided
in Section 8.2 are based on the best information available at the time
and typically assume the use of certain control techniques. The mention
of a specific technique should not be interpreted as an endorsement of
its use under all conditions. Lead smelters are, of course, not covered
by the proposed NSPS, and it is beyond the scope of the BID to review
the applicability of all control techniques for segments of the industry
not covered by the proposed standards for metallic mineral processing.
2.5 ENVIRONMENTAL IMPACTS
2.5.1 Comment: (IV-D-11, IV-D-14, IV-D-16, IV-D-18) Several commenters
stated that the air quality benefits attributable to the proposed standards
were overstated because the emission reduction attributable to the
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proposed standards was overestimated. These commenters gave several
reasons why the emission reduction was overestimated. They reiterate
that the Agency assumed that the entire industry would be operating
under worst-case conditions when calculating the emissions that would
occur if the NSPS were not promulgated and if current State standards
were allowed to continue. They pointed out that the EPA's own testing
indicates that facilities operating under State standards with low-energy
wet scrubbers or baghouses are achieving much lower emission rates than
EPA's worst-case estimates. One commenter (IV-D-14) calculated that the
true emission reductions with the promulgation of an NSPS would be
closer to a 1000 tons per year as opposed to the EPA's estimate of
14,000 tons per year. These commenters also note that the number of new
metallic mineral plants predicted by the EPA is overestimated, particularly
in the copper and iron ore industry. Thus, the increase in industry
emissions that would occur from new plants if the NSPS were not promulgated
is overestimated. Finally, one commenter (IV-D-14) noted that new
plants often replace old plants; these old plant emissions should be
subtracted from the industry's emissions when calculating an increase in
industry-wide emissions if the NSPS were not promulgated.
Because the technology that must be employed to meet other Clean
Air Act requirements will reduce new source particulars emissions to
insignificant levels and because of the bleak outlook for future growth
in this industry, three of these commenters (IV-D-14, IV-D-16, and IV-D-18)
requested that the NSPS be withdrawn and that the industry be deleted
from the NSPS priority list.
Response: The EPA's estimates of the impacts of various regulatory
alternatives must be seen as that, as estimates made at a point in time
with the best information at hand. In predicting the likelihood of new
facilities in the industry, the EPA consulted the best, sources available,
including the U.S. Bureau of Mines, industry representatives, technical
journals, and State agencies. Typically, these sources do not specify
particular new plant developments; in their forecasts because of various
constraints. However, these sources do make various industry forecasts
in terms of long-range demand, sources of supply, and growth in the
industry. On this basis, the EPA developed models of new plants on
which to base its predictions of the costs and environmental impacts of
new standards.
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Since the time the EPA first developed these predictions, the
metallic mineral industry has experienced severe economic difficulties.
Numerous plants have suspended or reduced operations, and some new plant
construction has been postponed. Nonetheless, the EPA believes that,
because of the central role the metallic mineral processing industry
plays in the American economy, the long term prospects for growth in the
industry are good and the current difficulties experienced by industry
are only temporary.
In predicting the environmental impacts of various regulatory
alternatives, several methods could be used. The EPA could have chosen
to estimate the emissions that would occur if the State standards were
applied at new plants assuming that these emissions would be the maximum
allowed by the States. There are several problems with this approach.
State regulation of metallic mineral facilities was not consistent from
State to State or even within a State as to type of facilities at a
plant that might be required to meet State standards. Much of this
difficulty arose from the application of the term "unit process" to
plants when applying process weighted emission limitations. In addition,
affected facilities under the proposed standards might not be covered at
some locations if State standards continued. On the other hand, the
Agency's survey of the industry indicated that many plant facilities
covered by State standards were doing better than State standards and
that a percentage of the new plants might be expected to do likewise.
Alternately, the Agency could assume the average emission level
measured at facilities that the EPA actually tested. There are also
problems with this approach. The Agency could not perform an exhaustive
test survey of all types of facilities in the industry to determine what
the current emission levels are in the industry. Such a test program
would not have been a wise use of tax dollars and would not have fulfilled
the primary purpose of the EPA's test program. The EPA selects and
tests well-designed and well-maintained types of control devices to
determine the levels of performance. Some facilties that the EPA inspected,
but did not test, were operating with control system designs, devices,
or maintenance programs that were not best systems; although, they were
meeting State standards. For example, some facilities are able to use
dry cyclones to meet State standards. These control devices were not
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tested because they are not examples of best systems of continuous
emission reduction.
Therefore, the Agency decided to use the so-called "worst-case"
approach in calculating emission impacts of the various regulatory
alternatives. This approach assumes a baseline emission level equivalent
to the emissions from a low pressure drop scrubber operating under
worst-case conditions. The EPA agrees that this approach will not
predict the true impact of the proposed standard at each and every new
plant that might be built. However, compared to the results of other
predictive methods, the Agency feels this method gives a valid overall
indication of the impact of the standard. Although the "worst-case"
method will overestimate the impact at some facilities it will not do so
as greatly as using the maximum emissions allowed by the States as a
basis for calculating the impacts. On the other hand, the "worst-case"
approach presumes the use of a wet scrubber that may provide better
control than a dry cyclone. The "worst-case" approach also presumes
coverage of all affected facilities at a plant by the State standards
even though State standards may not consistently require control devices
on all of these facilities. Uncontrolled emissions from these facilities
could easily be higher than "worst-case" baseline emissions of 0.15 gr/dscf.
Also, the EPA did not specifically enumerate the reconstruction of
facilities at existing plants in estimating emission reductions. The
"worst-case" approach used to calculate the environmental benefit of the
standard also corresponds to the approach used to calculate the control
cost of the standard.
Although the estimates of environmental impacts are approximations,
they indicate significant emission reductions such that the NSPS will
not result in unnecessary regulation as claimed by some commenters.
Because of the expected long-term growth in the industry arising from
the construction of new facilities and the reconstruction of existing
facilities, this source category will remain listed as a significant
source on the priority list for which standards of performance will be
promulgated.
2.5.2 Comment: (IV-D-14) One commenter proposed that, if the Agency
could not be persuaded to withdraw the standards for reason of minimal
environmental impact, then the standards should be applied only to
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dryers not covered by the smelter standards. This commenter noted that
dryers were the only facilities that the EPA tested that did not meet
the proposed standards with the low pressure drop scrubber. This commenter
also noted that most new facilities will use wet grinding operations
(which do not require control devices) instead of dry secondary and
tertiary crushing operations as proposed in the EPA's model new plants.
Response: As noted elsewhere in this document, the Agency tested
examples of well-designed and well-maintained control devices. The
EPA's survey of the industry under Section 114 of the Clean Air Act
indicates that there are facilities in addition to dryers in this industry
that are operating with devices that are not best systems of continuous
emission reduction and that emit particulate matter at levels higher
than the proposed standards.
The use of wet grinding has increased in the industry during the
recent past. However, combined crushing and grinding facilities have
been designed and are possible in the future as discussed in the Background
Information Document prepared for the proposed standard. Therefore, the
Agency will continue the inclusion of all types of dry crushing operations
in the standards.
2.6 ENERGY IMPACTS
2.6.1 Comment: (IV-D-11, IV-D-14) Two commenters noted certain
liabilities with the use of high-energy wet scrubbers. Additional
energy consumption from high-energy scrubbers could be the equivalent of
50,000 barrels of oil a year. Even though this is a small percentage of
total plant use, it is still a significant quantity. Additionally, the
noise levels from high-energy wet scrubbers will be higher than from
low-energy scrubbers and will increase personnel noise exposure.
Response: The EPA is aware that the energy consumption of high-energy
wet scrubbers is a significant percentage of their annualized cost. On
an industry-wide basis, however, the use of baghouses and low- and
medium-energy scrubbers will greatly reduce the overall energy impacts.
Even assuming the universal application of high-energy scrubbers, which
is highly unlikely, their energy consumption would be less than one-half
of 1 percent of the total energy consumption of new plants.
The noise levels associated with wet scrubbers, though not as high
as processing equipment such as crushers, may still require hearing
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protection for workers in close proximity. The placement of scrubbers
at roof level will mitigate some of these impacts.
2.7. TEST METHODS AND MONITORING
2.7.1 Comment: (IV-D-2, IV-D-3, IV-D-12, IV-D-13, IV-D-14, IV-D-15,
IV-D-16, IV-D-18, IV-D-19) A number of commenters noted that no method
is specified in the proposal for the determination of the opacity of
process fugitive emissions or stated that Method 9, which is specified
in the General Provisions, is not appropriate for this measurement.
These commenters note that Method 9 was developed for reading opacity at
stacks and that the diffuse nature of process fugitive emissions will
render Method 9 readings highly variable and subjective. Further, the
data used in setting the standard are inappropriately based on Method 9
results in that no procedures for measuring opacity of process fugitive
emissions are provided in Method 9. The commenters recommended that the
process fugitive emission standard be deleted until an appropriate
method is developed.
Response: As stated in the General Provisions (40 CFR 60.11),
Method 9 is the method specified for the determination of opacity. The
Agency agrees that Method 9, as written, does not provide sufficient
guidance for the measurement of opacity levels from process fugitive
sources. During the data collection in support of the metallic minerals
processing regulation, observers trained in the use of Method 9 followed
the guidelines of the method with some modifications in recording visible
process fugitive emission data. Method 9 has been amended to incorporate
these modifications, which explain in more detail how the opacity of
visible process fugitive emissions is determined. The amendment emphasizes
the correct positioning of observers and the location within the visible
fugitive emissions where opacity readings are to be made.
2.7.2 Comment: One commenter (IV-0-9) noted that the certification
section in Method 9 requires readers to achieve an average observational
error of no greater than 7.5 percent. The commenter suggested that any
opacity standard set below ths 7.5 percent level is inconsistent with
Method 9 because it requires the observer to be more precise than required
by the certification section (which the commenter contends governs the
issue of what error enforcement personnel must consider). The commenter
also implied that, by not allowing full use of an average 7.5 percent
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negative error, the proposed 7 percent stack opacity standard somehow
penalizes the facility owner. Another commenter (IV-D-8) advanced a
similar argument.
Response: The introductory paragraphs in Method 9 describe the
"positive observational error" to be taken into account for the enforcement
purposes. (Positive error is a reading higher than the actual opacity
level.) The purpose of these paragraphs is only to insure that sources
subject to opacity standards are not penalized for apparent violations
that are due to observational error. The paragraphs do not suggest, nor
is it true, that Method 9 is not accurate enough to establish and enforce
opacity standards as low as 0 percent opacity. See 40 C.F.R. §60.302
(0 percent opacity standards in NSPS for grain elevators); 40 C.F.R.
§60.372 (0 percent opacity standard in NSPS for lead acid battery
manufacturing).
It is unclear how an owner could be penalized for not "accounting"
for negative error in enforcement proceedings. Negative error is the
degree to which a reading is lower than the actual opacity level.
Inaccurately low readings can only benefit facility owners. For this
reason, observers need not compensate for them to avoid penalizing
owners unfairly.
Moreover, contrary to the commenters1 suggestions, Method 9 does
not require that the maximum 7.5 percent positive error discussed in the
section entitled Certification Requirements be taken into account for
enforcement purposes. The only portion of Method 9 addressing the
enforcement issue is the introductory section. That section requires
that the accuracy of the method be considered for enforcement purposes
and describes that accuracy in terms of the following ranges of positive
error derived from extensive data obtained in the field:
1) For black plumes . . ., 100 percent of the sets were read
with a positive error of less than 7.5 percent opacity;
99 percent were read with a positive error of less than
5 percent opacity.
2) For white plumes . . .,99 percent of the sets were read
with a positive error of less than 7.5 percent opacity;
95 percent were read with a positive error of less than
5 percent opacity.
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This language does not suggest an average positive error of 7,5 percent.
Nor is it appropriate to consider for enforcement purposes the
maximum average 7.5 percent error that observers are permitted for
qualification purposes under the certification section. During the
certification test, the observer is challenged with plume opacities that
are randomly varied from 0 to 100 percent opacity for each group of
25 readings. This contrasts sharply with the range of opacities with
which qualified readers are typically challenged on field inspections.
In the field, an observer can expect that opacities from a given stack
will usually vary within only a narrow range during the 6-minute time
span encompassing a set of 24 readings. In the Administrator's judgment,
an observer's error, when reading plumes with relatively constant opacity
levels, will be significantly less than the observer's error when reading
a full range of randomly varied opacity levels. Since readers enforce
opacity limits in the field, the EiPA properly required that the range of
error demonstrated under field conditions, rather than the maximum
allowable average error associated with certification testing in an
artificial environment, be considered for enforcement purposes.
2.7.3 Comment: (IV-D-8, IV-D-9, IV-D-13, IV-D-15) A number of commenters
noted that as Method 9 readings are collected in increments of 5 percent
opacity, the emission limit should be stated as an increment of 5 percent
opacity.
Response: Opacity results from Method 9 tests represent the average
of 24 readings over a 6-minute period. While each reading is recorded
as an increment of 5 percent opacity, the average of all the readings
can be any value. The new source performance standard is based on
6-minute averages and, therefore, is not limited to an interval of
5 percent opacity.
2.7.4 Comment: (IV-D-9) One commenter suggested that the opacity data
be normalized for stack diameter and that a statistical analysis be
included in the procedure.
Response: The new source performance standard support data represent
measurements from different stack sizes and configurations. The
recommended emission limit accounts for differences between stack
configurations in that the limit is set above the highest observed
values. There is no need to perform any further statistical evaluation
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or normalization of the data in order to show compliance with an emission
standard set in this manner.
The opacity standard for stack emissions would be applicable in all
cases unless the EPA were to approve establishment of a special opacity
standard under the provisions of 40 CFR 60.11(e). The provisions allow
an owner or operator to apply to the EPA for establishment of a special
opacity standard for any source that meets the applicable concentration
standard (demonstrated through performance tests under conditions
established by the EPA) but is unable to meet the opacity standard
despite operating and maintaining the control equipment so as to minimize
opacity. A special opacity standard might be established, for example,
where an unusually large diameter stack precludes compliance with the
proposed opacity standard.
2.7.5 Comment: (IV-D-11) One commenter stated that the requirement
for initial performance tests was extremely costly particularly at
plants with up to 25 control devices. At $5,000 to $9,000 per test,
this could cost up to $250,000.
Response: Initial performance tests are required by the General
Provisions (40 CFR 60.8). Although their cost is a relatively small
percentage of the cost of control equipment, which in turn is a relatively
small percentage of the capital cost of new plants, the EPA recognizes
that the cumulative cost of these tests can be significant. Several
factors should be seen as mitigating these costs. At plants with a
large number of control devices economies of scale would reduce the cost
of testing to at least the lower end of the price range quoted above.
In addition, the General Provisions (40 CFR 60.8(b)) provide authority
for waiving of performance tests. For example, the enforcing agency
could limit testing to a representative sample of similar control devices
at a specific site.
2.7.6 Comment: (IV-D-11, IV-0-12, IV-D-18) Several commenters provided
comments on the requirements for wet scrubber monitoring devices. One
commenter (IV-D-11) stated that the wet scrubber monitoring devices are
costly and unnecessary because the Background Information Document
showed that most devices were operating properly with zero opacity. The
two other commenters suggested that the regulation be clarified to
indicate that opacity limits on baghouses and wet scrubber monitoring
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devices were meant as quick performance checks and that continuous
performance records are not required.
Response: As discussed in the preamble and in Chapter 4 of the BID
for the proposed standards, some wet scrubbers showed no stack opacity;
however, as a whole the stack emission opacity data collected during the
tests of wet scrubbers were inconclusive due to their high variability.
Some of the highest opacity readings (e.g., 25 percent) were observed at
low outlet particle concentrations (e.g., 0.006 gr/dscf); while at other
facilities with outlet concentrations closer to the stack emission
limits, opacity was essentially zero. Therefore, an opacity standard
was not proposed for wet scrubbers. Instead, the monitoring of the
operating parameters of wet scrubbers (pressure drop and scrubber liquid
flow rate) would be required by the proposed standards in order to
provide an inexpensive and easily verifiable check of the operation and
maintenance of wet scrubbers. The annualized cost of these monitors is
reasonable, ranging from about 1 percent of the control device cost at
large iron ore plants to 7 percent at small tungsten plants.
The EPA's experience with control devices shows that regular
maintenance, both remedial and preventive, greatly enhances control
equipment efficiency and reduces overall control costs. The installation
of wet scrubber monitoring devices will greatly improve the ability of
maintenance personnel to detect a gradual decrease in scrubber performance
before a major breakdown occurs. Thus, the installation of these devices
is justified in terms of insuring proper operation and maintenance of
wet scrubber control devices.
The General Provisions require recordkeeping for continuous monitoring
devices. Therefore, Section 60.384 of the proposed standards has been
revised to clarify the type of recordkeeping required for wet scrubber
monitoring devices. The owner or operator of a wet scrubber would be
required to record the liquid flow rate and the change in pressure of
the gas stream at the time of the initial performance test and at least
weekly thereafter. The owner or operator would be required to report
the liquid flow rate and the change in pressure of the gas stream at the
time of the initial performance test. Semiannual reporting of the
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subsequent weekly readings is only required when one or more readings of
the liquid flow rate or pressure varies by more than ±30 percent from
the readings of the most recent performance test.
2.7.7 Comment: (IV-D-8) One commenter noted that the accuracy
requirement for liquid flow meters on wet scrubbers was upgraded from
±10% to ±5%. The commenter requested an explanation of the change.
Response: The Agency surveyed suppliers of these devices and found
that they can be routinely guaranteed as accurate to at least ±5 percent.
In fact, devices more accurate than those prescribed by the standard are
typically the norm in the industry. Therefore, the specifications were
changed in line with industry standards.
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Table 2-1. LIST OF COMMENTERS ON THE PROPOSED STANDARDS
OF PERFORMANCE FOR METALLIC MINERAL PROCESSING PLANTS
Docket entry number3 Commenter/affiliation
IV-D-1 D. L. Shepherd
2528 Aval on Avenue, Northwest
Roanoke, Virginia 24012
IV-D-2 D. B. Crouch
Homestake Mining Company
650 California Street
San Francisco, California 94108
IV-D-3 D. G. Doughty
Oklahoma State Department of Health
1000 Northeast 10th Street
Post Office Box 53551
Oklahoma City, Oklahoma 73152
IV-D-4 D. E. Cochran
Duval Corporation
4715 East Fort Lowell Road
Tucson, Arizona 85712
IV-D-5 Francis W. Giaccone
Air Facilities Branch
Air and Waste Management Division
EPA, Region II
26 Federal Plaza
New York, New York 10278
IV-D-6 E. J. Weathersbee
Department of Environmental Quality
522 Southwest 5th Avenue
Box 1760
Portland, Oregon 97207
IV-D-7 L. A. Pirozzoli
Heel a Mining Company
Post Office Box 320
Wallace, Idaho 83873
IV-D-8 J. H. Goldman, Ph.D.
The Aluminum Association, Incorporated
818 Connecticut Avenue, Northwest
Washington, D.C. 20006
(continued)
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Table 2-1. Continued
Docket entry number3 Commenter/affiliation
IV-D-9 L. C. Tropea, Jr., P.E.
Reynolds Aluminum
Reynolds Metals Company
Richmond, Virginia 23261
IV-D-10 E. R. Bingham
Amax Environmental Services, Inc.
1707 Cole Boulevard
Golden, Colorado 80401
IV-D-11 A. R. Coy
Evans, Kitchel & Jenckes, P.C.
2600 North Central Avenue
Phoenix, Arizona 85004-3099
Attorney for Phelps Dodge Corporation
IV-D-12 J. H. Boyd
Newmont Services Limited
Post Office Box M
San Manuel, Arizona 85631
IV-D-13 C. B. Scott
Union Oil Company of California
Union Oil Center
Box 7600
Los Angeles, California 90051
IV-0-14 K. E. Blase
Prather, Seeger, Doolittle & Farmer
1101 Sixteenth Street, Northwest
Washington, D.C. 20036
Attorney for Kennecott Minerals Company
IV-D-15 A. L. Scott
Kerr-McGee Corporation
Kerr-McGee Center
Oklahoma City, Oklahoma 73125
IV-0-16 L. C. Turnock
American Iron Ore Association
1501 Euclid Avenue
514 Bulkley Building
Cleveland, Ohio 44115
(continued)
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Table 2-1. Concluded
Docket entry number3 Commenter/affillation
IV-D-17 B. Blanchard
United States Department of the Interior
Office of the Secretary
Washington, D.C. 20240
IV-D-18 J. A. Overton, Jr.
American Mining Congress
Suite 300
1920 North Street, Northwest
Washington, D.C. 20036
IV-D-19 J. C. Parrel!
Freeport Gold Company
Mountain City Star Route
Elko, Nevada 89801
IV-D-20 W. R. Chalker
E. I. duPont de Nemours & Company
Engineering Department
Louviers Building
Wilmington, Delaware 19898
These designations represent docket entry numbers for Docket
No. A-81-03. These documents are available for public inspection at:
U.S. Environmental Protection Agency, Central Docket Section, West
Tower Lobby, Gallery 1, Waterside Mall, 401 M Street, Washington, D.C.
20460.
This memo is an internal EPA document that was inadvertently put into
the docket and was subsequently withdrawn from the docket.
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing}
1. REPORT NO.
EPA-450/3-81-009C
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Metallic Mineral Processing Plants
Background Information for Promulgated Standards
5. REPORT DATE
January 1984
6. PERFORMING ORGANIZATION CODE
7. AUTHOR
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