TRC
TRC Environmental Corporation
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MODEL OPERATING PERMIT FOR PM10 EMISSIONS
FROM CALCINERS AND DRIERS IN THE MINERAL INDUSTRIES
DRAFT REPORT
November 1992
Prepared by
TRC ENVIRONMENTAL CORPORATION
100 Europa Drive, Suite 150
Chapel Hill, NC 27514
EPA Contract No. 68-DO-0121
Work Assignment No. 11-91
EPA Work Assignment Manager: W. Stephen Fruh
Emission Standards Division
Office of Air Quality Planning and Standards
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
THIS DOCUMENT HAS NOT BEEN PEER OR ADMINISTRATIVELY
REVIEWED WITHIN EPA AND IS FOR AGENCY USE/DISTRIBUTION
ONLY. DO NOT QUOTE, CITE OR DISTRIBUTE.
(CH-91-16u)
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DISCLAIMER
This Draft Final Report was prepared for the Emission Standards Division,
U.S. Environmental Protection Agency, Research Triangle Park, North Carolina by
Alliance Technology Corporation, operating under the name TRC Environmental
Corporation, 100 Europa Drive, Chapel Hill, North Carolina 27514, in partial
fulfillment of Contract No. 68-DO-0121, Work Assignment No. 11-91. The opinions,
findings and conclusions expressed are those of the authors and not necessarily
those of the Environment Protection Agency.
CH-91-16u 11
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TABLE OF CONTENTS
Section Page
List of Tables iv
1.0 Introduction 1-1
2.0 Sources of Emissions 2-1
2.1 General 2-1
2.2 Dryers 2-1
2.3 Calciners 2-3
2.4 References 2-5
3.0 Model Permit for Calciners and Dryers in the Mineral Industries . . 3-1
3.1 Introduction 3-1
3.2 Specific Conditions 3-2
3.2.1 Example of Specific Conditions for Calciners and for
Calciners and Dryers Installed in Series 3-2
3.2.2 Example of Specific Conditions for Dryers 3-2
3.3 Control Equipment Operating Parameters 3-4
3.3.1 Fabric Filter Operating Parameters 3-4
3.3.2 Electrostatic Precipitator Operating Parameters 3-4
3.3.3 Mechanical Collectors Operating Parameters 3-4
3.3.4 Scrubber Operating Parameters 3-4
3.4 Monitoring Requirements 3-5
3.5 Testing Requirements 3-6
3.6 Recordkeeping Requirements 3-7
3.7 Reporting Requirements 3-8
3.8 References 3-9
CH-91-16u i i i
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LIST OF TABLES
Number Page
2-1 Types of Dryers and Calciners used by Industry 2-2
CH-91-16U IV
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1.0 INTRODUCTION
Title V of the 1990 Clean Air Act Amendments (CAAA) requires States to
adopt operating permit programs to be administered by State or local air
pollution control agencies. The programs are to issue operating permits to major
stationary sources of criteria and hazardous air pollutants, sources covered by
new source performance standards (NSPS), sources covered by national emission
standards for hazardous air pollutants (NESHAP), sources regulated under the acid
rain program (Title IV Acid Deposition Control) and the stratospheric ozone
program (Title VI Stratospheric Ozone Protection), and sources covered by State
implementation plans.
The permits must meet several requirements. They must contain all the
applicable pollution control obligations of a source such as those imposed by
State implementation plans and NSPS under the authority of Title I of the CAAA,
under the air toxics program of Title III of the CAAA, under the acid rain
program of Title IV of the CAAA, or under other applicable provisions of the
CAAA. As necessary, the operating permits are to establish maximum source
operating rates, maximum pollutant emission rates and/or pollutant control
methods, and methods for determining compliance with the emission limits or
control methods.
Emissions from many sources of particulate matter (PM) are regulated under
the above titles of the CAAA including State implementation plans for particles
with an aerodynamic diameter less than or equal to a nominal 10 microns (PM,0).
Therefore, operating permits will be required for several categories of sources
that emit PM. The processes and operations for calciners and dryers used in the
mineral industries which cause PM emissions are discussed in this document, and
an operating permit for this source category is presented as a model that may be
used in implementing a permit program. This model permit covers only the
particulate matter aspects of this source category; it does not cover other
pollutants for which the source may be regulated.
CH-91-16u 1-1
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2.0 SOURCES OF EMISSIONS
2.1 GENERAL
The source category for mineral dryers and calciners includes process
equipment used to dry and calcine seventeen types of minerals, as shown in Table
2-1.' Drying is the removal of uncombined (free) water from mineral material
through direct or indirect heating, while calcining is the removal of combined
(chemically bound) water and/or gases through direct or indirect heating.
Processing plants for these mineral industries are located domestically in 43
States and in the Virgin Islands. Several of the mineral processes are composed
of a large number of individual facilities located in many States, while others
are limited to relatively few plants located near natural deposits of the
minerals being processed. The mineral industries considered in this source
category use a wide variety of processing equipment for the drying and calcining
of raw materials.
2.2 DRYERS
Dryers are used by the mineral industries to remove uncombined water from
mineral materials. In general, dryers use either a convection (direct) or a
conduction (indirect) method of drying. In the convection method, a heating
medium, usually air or combustion products, is in direct contact with the wet
material. In the conduction method, heat is transmitted indirectly through a
heated surface which directly contacts the wet material.2
Rotary dryers are the most frequently used dryer type in the mineral
industries. A rotary dryer consists of a cylindrical shell, ranging in length
from 4 to 10 times its diameter, into which wet charge is fed at one end and from
which dried product is discharged at the other end. Material is moved through
the dryer by the combined effects of horizontal shell inclination and the action
of lifting flights within the shell. As the shell rotates, the lifting flights
pick up the material and shower it as a curtain in the path of hot gases. Direct
rotary dryers are used when the materials to be dried can be safely brought into
contact with heated air or combustion gases and when volatile, flammable, or
noxious components are entirely absent or present only in small amounts. The
drying medium, heated air or combustion gas, is fed into the dryer at one end and
is drawn out the other end, coming into contact with the mineral as it flows
through the dryer. The gases may move either concurrently or countercurrently
with the movement of the process material.2
CH-91-16U 2-1
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TABLE 2-1. TYPES OF DRYERS AND CALCINERS USED BY INDUSTRY*
no
I
ro
Mineral Type
Alumina
Ball clay
Bentonite
Diatomite
Feldspar
Fire clay
Fuller's earth
Gypsum
Industrial sand
Kaolin
Lightweight
aggregate
Magnesium
compounds
Perlite
Roofing granules
Talc
Titanium dioxide
Vermiculite
Rotary Rotary
direct Indirect
X
X
X
X
X
X
X
X
X
X
X
X
X X
X
Dryers
Fluid Vibrating Flash Spray
bed grate
X
X
X
X
X
X
X
X
X
X
X XX
X
Rotary Flash
X X
X
X
X
X
X X
X
X
X
X
Calciners
Hearth Kettle Expansion
furnace furnace
X
X
X
X
X
"Reference 1.
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Fluid bed dryers are also commonly used by the mineral industries. In a
typical fluidized bed dryer, wet feed material is charged in batch or continuous
mode to the dryer above the bed. The wet feed bed expands due to the high
velocity of the hot gas stream rising from beneath the bed of particulate solids.
The solid particles become suspended, thus creating a fluidized bed. In a fluid
bed dryer, efficient mixing of the solid particles results in uniform drying.
Thus, the gas stream velocity is controlled to yield optimum conditions for
drying with regard to particle size and density. Product discharge rate and gas
temperature are also monitored to obtain the desired product moisture content.2
Dried product is removed near the base of the vessel. Gas is exhausted through
the top of the dryer to a control device.
Other dryer types used in the mineral industries include indirect rotary,
flash, spray, and vibrating grate. Indirect rotary dryers are used if the
process material cannot be exposed to combustion gases, if excessive dust carry-
over may occur through entrainment, if low-cost steam is available, or if
volatile components desirable for recovery are present.2 Flash dryers are
designed to dry material and convey it by a stream of hot gases from the feed
point to a point of delivery.2 Separation of the dried product from the
conveying air usually takes place in a cyclone, followed by further separation
in other cyclones or baghouses. Spray dryers are used to dry liquids, slurries
and pastes. Vibrating-grate dryers are suitable for free-flowing solids
containing mostly surface moisture. They are not effective on fibrous materials
that form a mat, or on sticky solids that agglomerate or adhere to the deck.
2.3 CALCINERS
Calciners are designed to remove the majority of combined moisture in the
process material and are operated at higher temperatures than the dryers. In
general, a calciner has up to four zones of heating, each of which has a
different heat transfer rate. These include a feed drying zone, a heating zone
where charge is heated to the reaction temperature, a reaction zone where process
material is reacted and bound moisture is removed, and the soaking zone (wet-feed
calciners only) where reacted charge is super-heated or "soaked" at the desired
temperature or cooled before discharge.3 Rotary and flash calciners are the most
common types of calciners used in the mineral industries.
A rotary calciner consists of a cylindrical shell into which wet charge
(wet feed) or predried (dry feed) material is fed at the elevated end by various
methods including chutes, overhung screw conveyors, and slurry pipes. The
material is heated, reacted and super-heated. The primary source of heat
transfer in rotary calciners is radiation from the refractory to the material
bed. Since most rotary calciners have countercurrent air and material flow to
CH-91-16U 2-3
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achieve the most energy efficient reduction in moisture content, secondary heat
transfer occurs by convection from the hot gas to the exposed material bed
surface.3 Natural gas, oil, or pulverized coal may be used as fuel for the
heating source. The calcined product is discharged at the other end into quench
tanks, conveyors, or cooling devices.
Flash calciners are similar to flash dryers in principle and operation
except that flash calciners operate at higher temperatures. Both multi-stage and
direct contact flash calciners are used in the mineral industries. A typical
flash calcining unit consists of a two-stage cyclone, a preheater, a venturi-type
flash dryer, the calciner, a multi-stage cyclone cooler, and a secondary fluid
bed cooler. Partly calcined material formed in the cylindrical heating zone of
the calciner is discharged into the reactor just above the fuel inlet. The
calcined material is retained for a few seconds and is then separated from hot
gases in the separation cyclone, prior to being discharged into the primary
cooler. Natural gas and distillate fuel oil are the primary heating fuels used
in flash calciner installations.
Other calciner types used in the mineral industries include multiple hearth
furnaces, kettle calciners, and expansion furnaces. Multiple hearth furnaces
handle granular material and provide a long countercurrent path between flue
gases and process material. Kettle calciners are constructed from cylindrical
metal shells, which are set in masonry brick and surrounded by a steel jacket.
Although some kettle calciners are designed to operate in only a batch mode, most
kettle calciners can be operated in either batch or continuous modes. Expansion
furnaces are used to process ore that "expand" up to 20 times their original
volume when exposed to high temperatures.
Particulate matter emissions from drying and calcining result from
entrainment of dust and fly ash particles in the gas stream passing through the
equipment, with subsequent carryover to the exhaust system. The variables that
affect emissions from calciners include the gas velocity through the unit; the
characteristics of the feed material; and the fuel type.1
CH-91-16u 2-4
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2.4 REFERENCES
1. U.S. Environmental Protection Agency. Calciners and Dryers in Mineral
Industries - Background Information for Proposed Standards. EPA-450/3-85-
025a. Office of Air Quality Planning and Standard, Research Triangle
Park, NC, October 1985.
2. Williams-Gardner, A. Industrial Drying. Gulf Publishing Company,
Houston, TX, 1977.
3. Porter, H.F., G.A. Schurr, D.F. Wells, and K.T. Semrau. Solids Drying and
Gas-Solid Systems. In: Chemical Engineers' Handbook. 6th Edition, Perry,
R.H., D.W. Green, and J.O. Maloney (eds.). McGraw-Hill, New York, 1984.
CH-91-16U 2-5
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3.0 MODEL PERMIT FOR CALCINERS AND DRYERS USED IN THE MINERAL INDUSTRIES
3.1 INTRODUCTION
Section 190 of Title I of the Clean Air Act Amendments of 1990 requires the
Administrator of the U.S. Environmental Protection Agency to provide guidance to
State and local agencies on categories of sources that contribute to
nonattainment of the PM,0 national ambient air quality standard. As part of that
guidance, Section 3.5 provides specific conditions that may be included in
operating permits that would apply to PM]0 emission sources from calciners and
dryers used in the mineral industries. These specific conditions should be
considered as guides for States to use in designing their own operating permit
programs.
Individual facilities should be permitted on a case-by-case basis, and the
emission limits included in the permit should be based on State implementation
plan (SIP) regulations applicable in the area where the source is located. Where
applicable, the mass and visible emission limits on an emission source and the
operating conditions should be sufficiently detailed in the permit to allow a
clear determination of whether the source is or is not in compliance. At a
minimum, the permit should contain the following components:
• A fixed term, not to exceed five years [Section 502(b)(5)(B)];
• Limits and conditions to ensure compliance with all applicable
requirements under the Act, including requirements of the applicable
implementation plan [Section 504(a)];
• A schedule of compliance, which is defined as a schedule of remedial
measures, including an enforceable sequence of actions or operations,
leading to compliance with applicable requirements under the Act [Sections
504(a) and 501(3)];
• Inspection, entry, monitoring, compliance certification, recordkeeping and
reporting requirements to ensure compliance with the permit terms and
conditions consistent with any monitoring regulations that EPA promulgates
under Section 504(b) [Section 504(c)];
• A provision describing conditions under which any permit for a major
source with a term of three or more years must be reopened to incorporate
any new standard or regulation promulgated under the Clean Air Act
[Section 502(b)(9)];
CH-91-16U 3-1
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• Provisions under which the permit can be revised, terminated, modified, or
reissued for cause [Section 502(b)(5)(D)]; and
• Provisions ensuring operational flexibility within a permit so that
certain changes can be made without a permit revision, if no
"modification" (as defined in Title I of the Act) would occur and the
changes do not exceed the emissions allowable under the permit (whether
expressed as a rate or in terms of total emissions) provided that a notice
is sent to the permitting authority at least seven days in advance of the
change [Section 502(b)(10)].
Examples of the following sections of a typical operating permit will be
provided in a separate document:
Source Identification
Findings of Fact, Conclusions of Law, Decisions
General Conditions
Compliance Conditions, and
Operational Flexibility
CH-91-16U ' 3-2
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3.2 SPECIFIC CONDITIONS
3.2.1 Example of Specific Conditions for Calciners and for Calciners and Dryers
Installed in Series
1. The permittee shall not jcause or, allow the [ipeHfyrijpVf||]
processing rate to exceed [^"^p^Yfr;T|^^ayy^d^-w^^
. I - •+? * ••"• "* •. ' *i*ff!*mW ***^ f * V""lri'H" f S i. "V 4*.t* '"*'A JJ**?^W.A W.WA* WV.*
in each [cafcuwfr^wro cslcfiTer^ ^;^^r^--^1«st^1|f3[ ^-^$e|fs$j
(maximum design capacity as specified in uies "permitsvappVfcatToii)T
2. The permittee shall determine the [spetlfyWriemf] processing rate
daily by weight. s "' ".""
3. The permittee shall not cause or allow to be discharged into the
atmosphere from the outlet of any control device for calciners and
for calciners and dryers installed in_seriesAjnymjase^tJ)at £onta
particulate emissions in excess of [["''T""tJK^-""'*"*"'"*' - ™3™-^-
4. The permittee shall not cause or allow to be discharged into the
atmosphere from the outlet of any dry control device for calciners
and for calciners and dryers installed in series any gases that
exhibit visible emissions greater than [T^rifr^enf] opacity.
5. This section should contain operating parameters for the control
equipment applied at this emission point (See Section 3.3 for
example operating parameters).
3.2.2 Example of Specific Conditions for Dryers
1. The permittee shall not %cause or allqw_the [^Vecify^ifpefil]
processing rate to exceed L % J^ffiay { " ".'."tos$/3ayH rdryVe fgKt ,
in each dryer (maximum design capacity as specified in the permit
application).
2. The permittee shall determine the [^ecify~4W%rat] processing rate
daily by weight.
3. The permittee shall not cause or allow to be discharged into the
atmosphere from the outlet of a control device for any dryer any
gases that contain particulate emissions in excess of ["^vv ¥-">^--~
4. The permittee shall not cause or allow to be discharged into the
atmosphere from the outlet of a dry control device for anyjdryerany
gases that exhibit visible emissions greater than [^^I^i^^^ni]
opacity.
5. This section should contain operating parameters for the control
equipment applied at this emission point (See Section 3.3 for
example operating parameters).
Note: Specific control, performance and reporting
information contained in thie model permit • provided solely
for akwtrative purpome and ie not intended to ectabRth
CH-91-16U 3~3 ndmtriaj norm* or national itandanh.
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3.3 CONTROL EQUIPMENT OPERATING PARAMETERS
The parameters listed in this section are provided as examples of typical
control equipment operating conditions that should be specified. There
may be other important parameters not listed below.1
3.3.1 Fabric Filter Operating Parameters
Air/Cloth Ratio:
Pressure Drop Across Baghouse: in. H20 (MIN) in. H20 (MAX)
Inlet Air Temperature: (MIN) (MAX)
Outlet Air Temperature: (MIN) (MAX)
Inlet Air Flow Rate:
3.3.2 Electrostatic Preclpitator Operating Parameters
Pressure Drop:
Inlet Air Temperature: (MIN) (MAX)
Outlet Air Temperature: (MIN) (MAX)
Gas Velocity through (ESP): ft/sec
Conditioning Agent Additions: gr/ft3
Voltage and Current Readings for each Transformer-Rectifier (T-R) Set:
Example: first 3 fields - 3 at 50 KVA
(55 kVp, 35 kV8V, 500 mA)
last 2 fields - 4 at 64 KVA
(70 kVp, 45 kVw, 500 mA)
3.3.3 Mechanical Collectors Operating Parameters
Gas Flow Rate: ft3/nrin
Pressure Drop: in. H20 (MIN) in. H20 (MAX)
Inlet Velocity: ft/sec
Inlet Air Temperature: (MIN) (MAX)
Outlet Air Temperature: (MIN) (MAX)
3.3.4 Scrubber Operating Parameters
Scrubbing Liquor:
Gas Flow Rate: ft3/min
Liquor Flow Rate: gal/min
Gas Pressure Drop Across Unit: in. H20 (MIN) in. H20 (MAX)
Liquid Pressure Drop Across Unit: psi.(MIN) psi (MIN).
Inlet Air Temperature: (MIN) (MAX)
Outlet Air Temperature: (MIN) (MAX)
Solids Content of Recirculated Scrubber Water: gr/gal
Note: Specific control, performance and reporting
information contained in thi> modal permit ia provided toMy
for iouatrativa purpoaaa and • not intended to evtabfoh
CH-91-16U 3-4 hdurtrial noima or national (tandardt.
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3.4 MONITORING REQUIREMENTS
1. The permittee shall install, calibrate, maintain, and continuously
operate for each dryer and calciner that uses a fabric filter or a
dry ESP control device, a continuous monitoring system to measure
and record the opacity of emissions discharged into the atmosphere
from the control device. The continuous monitoring device shall
be calibrated on a semiannual basis; or
2. If the facility employs a dry control device together with a
gypsum flash or kettle calciner or a perlite rotary dryer or
expansion furnace, the permittee may, in lieu of a continuous
opacity monitoring system, observe and record three six-minute
averages of the opacity of visible emissions from the control
device, once per week of operation.
3. When a wet scrubber is used to control particulate emissions, the
permittee shall install, calibrate, maintain, and operate
monitoring devices that continuously measure and record the
pressure loss of the gas stream through the scrubber and the
scrubbing liquid flow rate. The pressure_loss..jpjjtorijj3 device
shall be accurate to within plus/minus [^"^'tepiCliefgrl
i rr^flncBeV)"wat¥r,^asig^]. The 1 iquid ^Tbw*""ritT"inonft^ring
device shall be accurate to within plus or minus [^^"fHffCfrt£] of
the design scrubbing liquid flow rate. Both monitorTrig devices
shall be calibrated on a semiannual basis.
Note: Specific control, performance and reporting
information contained in thfe model permit » provided tolery
for JhjrtratJve purpoeee and " not intended to artafaish
CH-91-16U 3-5 industrial norm* or national ttandard*.
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3.5 TESTING REQUIREMENTS
Section 504(b) of the Clean Air Act, as amended, requires procedures and
methods for determining compliance and for monitoring and analyzing pollutants
regulated under the Act. An example of testing requirements that should be
included in the permit is provided below.
1. The permittee shall perform a compliance test for each emission
point from a stack or vent within 60 days of achieving the maximum
production rate at the facility, but no later than 180 days after
the initial start-up, and annually thereafter. EPA Reference
Method 5 shall be used to perform each compliance test on each
emission point from a stack. The s^ampljjig time and sample volume
for each run shall be at least [ ^Tho'urs] and [ - '3-J t IIIJl.l.^Z.T.T.jE.
{"\.d$cf}], respectively. Emissions testing shaTT be
•* .......... <**.~..tm.p* ' ' . . Jvt^-.fVmv. ,. ,•.•.•. v^s > . | . . . .
accomplished at a minimum of [^ j^r^epi] of the permitted
c|RaS.J.|l^J/ testing is performed 'at If rate of less than
[S7^jpifc¥ni;] of the permitted capacity, operation is restricted
tcTthe process input rate of testing at such level until a
subsequent compliance test is performed at a minimum of
capacity.
2. EPA Reference Method 9 and the procedures in 40 CFR 60.11 shall be
used to determine opacity.
3. During the initial performance test of a wet scrubber, the
permittee shall measure and record an arithmetic average of both
the change in pressure of the gas stream across the scrubber and
the liquid flow rate.
At least Q __ ^^JMlJ prior to performing a test, the owner
or operator sR'aTT""siiBm"if"a""test plan to the permitting authority
that describes the test duration, test locations, test methods,
source operation and other parameters that may affect test
results.
Note: Specific control, performance and repotting
information contained h this model permit ta provided tolely
for Murtrativu purpoMe and • not intended to ectabfith
CH-91-16U 3-6 Industrial norm* or national •tandard*.
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3.6 RECORDKEEPING REQUIREMENTS
Section 504(c) of the Clean Air Act, as amended, requires permits to contain
inspection, entry, monitoring, compliance certification, and reporting
requirements to ensure compliance with permit terms and conditions. Provided
below are examples of recordkeeping requirements.
1. Records shall be maintained for five years from the date of sample,
measurement, report, or application;
2. The permittee shall maintain the following records:
a. Compliance test reports for each affected vent;
b. For facilities which operate a gypsum flash or kettle
calciner or a perlite rotary dryer or expansion furnace,
weekly observances of three six-minute averages of the
opacity of visible emissions to the atmosphere from the dry
control device;
c. Daily pressure drop readings across control equipment (e.g.,
fabric filter, ESP, or wet scrubber);
d. Daily readings of liquid flow rate to the wet scrubber,
where applicable;
e. Daily mineral processing rate; and
f. Operating schedule.
Note: Specific control, performance and repmtng
Information contained h thii model permit • provided toWy
for iBuetrative purpoce* and « not intended to ertahfch
CH-91-16U 3-7 industrial norm or national (tandardi.
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3.7 REPORTING REQUIREMENTS
Provided below are examples of reporting requirements.
1. Records of any required monitoring shall be submitted at least every
six months and shall clearly identify all instances of deviations from
the permit requirements.
"The total mineral processing rate, in tons per day, shall be
recorded and submitted each quarter to the permitting authority."
2. Deviations from permit requirements, including those attributable to
upsets, shall be reported promptly, and the report shall include the
cause of such deviations and any corrective actions or preventive
measures taken. Corrective actions may include a requirement for
additional stack testing, or more frequent monitoring, or could trigger
implementation of a corrective action plan.
3. Exceedances that must be reported are defined as all six-minute periods
during^wMdhJthj average opacity from a dry control device is greater
than [^ ~ ~lif^£|&] > or any we* scrubber pressure drop or wet scrubber
liquid"Trow"jrat¥%that deviates more than plus or minus [,,,m,,"pferffiBi]
and [ Jjefceal], respectively, from the average value recoTdeOuring
initiaTTpe'rfol'ma'nce testing as specified in Section 3.5.4.3.
4. Definitions of deviations that trigger additional reporting
requirements should be as specific as possible.
"If the mineral processing rate exceeds the allowable rate as
specified in this permit, the permit holder shall immediately
notify the permitting authority and shall submit all records
specified under the Monitoring. Recordkeepinq and Reporting
subsections above within two days."
5. The permittee shall send $.w.9. C.P.P).?.S. °.f all reports required above to
the [|>sriifg&i"pt^^
6. Any document (including reports) required to be submitted by this
permit shall be certified as being true, accurate, and complete by a
responsible corporate official.
Note: Specific control, performance and reporting
Information contained in this modal permit '• provided soWy
for iduetrativa purposes and '• not intended to establish
CH-91-16U 3-8 industrial norm, or national standards.
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3.8 REFERENCES
U.S. Environmental Protection Agency. Technical Assistance Document:
Recommended Recordkeeping Systems for air Pollution Control Equipment
Part 1. Particulate Hatter Controls. EPA-340/1-86-021. Stationary
Source Compliance Division. Washington, DC. August 1987.
CH-91-16U 3-9
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