218.1

- 1 (Adopted May 14, 1999)

RULE 218.1 CONTINUOUS EMISSION MONITORING PERFORMANCE

SPECIFICATIONS

(a) Definitions

(1) ANALYZER

- the part of the continuous emission monitoring system
(CEMS) that analyzes the appropriate gaseous constituents of the

conditioned gaseous sample or measures stack gas volumetric flow and fuel
flow rates, as applicable.

(A) Contaminant Analyzer

- the part of the CEMS that detects the air
contaminant concentrations and represents those concentrations in
a signal output.

(B) Diluent Ana lyzer

- the part of the CEMS that detects oxygen,
carbon dioxide or other diluent gas concentrations as represents
those concentrations in a signal output.

(C) Fuel Flowmeter

- the part of the CEMS that detects the parameters

of all essential measurement s ub

- systems (e.g., temperature,
pressure, differential pressure, frequency, gas density, gas
composition, heating value) and generates signal outputs which are

a function of the fuel flow rate and all essential measurement sub

system parameters.
(D) Stack Flowmeter

- . the part of the CEMS that detects the
parameters from all essential measurement sub

- systems (e.g.,
temperature, static and atmospheric pressure, gas density, gas
composition, molecular weight, gas moisture content) and
generates signal outputs

which are a function of the stack gas

volumetric flow rate and all essential measurement sub

- system

parameters.
(2) CALIBRATION

- a procedure performed to ensure that the CEMS
accurately measures and records the concentration of the specific air

contamin ant or diluent gas, flow rate and other parameters necessary to
generate the required data, as evidenced by calibration checks and achieved
by periodic manual or automatic adjustment.

(3) CALIBRATION CHECK

- a procedure performed to determine CEMS

response to a given gaseous compound concentration by means of injectingRule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 2 a certified calibration gas mixture into the CEMS as close to the probe tip
as practical.

(4) CALIBRATION DRIFT (CD)

- change in the CEMS output or response
over a specific period of normal c ontinuous operation when the air
contaminant or diluent gas concentration at the time of the measurements is
the same known upscale value. CD is expressed as the sum of the absolute

value of the mean difference and the absolute value of the confidence

coe fficient of a series of tests, to the full span range, expressed as a
percentage as follows:

CD d CC

FSR = +

× 100

Where:

FSR = Full span range

CC = Absolute value of the 95% confidence coefficient

d = Absolute value o f the mean difference. The mean

difference, d , is calculated as:

d

n i i n 

### d =

= 

### ∑ 1

1

Where:

i i n 

### d

= 

### ∑

1 = Algebraic sum of the individual differences d i

n = Number of data points

d i = The difference between the paired response values of the monitoring system

(5) CALIBRATION ERROR (CE)

(A) CALIBRATION ERROR , as applicable to Section (c), “Standards
for Existing CEMS”

- the ratio of the difference between the air
contaminant or diluent gas concentration indicated b y the CEMS
and the known concentration of the calibration gas, to the known
concentration of the calibration gas. CE is calculated as the ratio of

the sum of the absolute values of the mean difference and the 95Rule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 3 percent confidence coefficient of a serie s of tests, to the gas
concentration, expressed as a percentage, as follows:

CE d CC

C = +

× 100

Where:

C = Calibration gas concentration

CC = Absolute value of the 95% confidence coefficient

d = Absolute value of th e mean difference. The mean

difference is calculated as:

d

n i i n 

### d =

= 

### ∑ 1

1
Where:

i i n 

### d

= 

### ∑

1 = Algebraic sum of the individual differences d i

n = Number of data pairs

d i = The difference between the paired monitoring

system response va lue and the known gas
concentration or the equivalent rating of the

reference method value, both in units of the
applicable standard

(B) CALIBRATION ERROR, as applicable to Section (b), “Standards

for New or Modified CEMS”

- the ratio of the absolute val ue of the
difference between the air contaminant or diluent gas concentration
indicated by the CEMS and the known concentration of the
calibration gas, to the full span range, expressed as a percentage,

as follows.

CE C A

FSR = − × 100

Where:

C = Calibr ation gas concentration

A = Actual response or the concentration indicated by the

monitoring systemRule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 4 FSR = Full span range of the instrument
(6) CEMS AVAILABILITY PERCENTAGE

- a percentage calculated as the
ratio of the total unit operating hours for which the CEMS provided
quality

- assured data, to the source total unit operating hours during a
specified period, excluding periods of calibration, maintenance, repair, or

audit

, up to a maximum of 40 hours per month.

(7) CERTIFIED CEMS

- a CEMS installed, test ed, operated, maintained, and
calibrated according to the applicable requirements of Rules 218 and 218.1;
that has met the applicable performance specifications of Rule 218.1 and,
has received written approval and conditions thereto applying, from the

Exec utive Officer.

(8) CERTIFIED GAS MIXTURE

- a gas mixture manufactured, analyzed and
certified in accordance with the “EPA Traceability Protocol for Assay and

Certification of Gaseous Calibration Standards”

- EPA

- 600/R97/121,
September 1997 Revision (EPA Tr aceability Protocol) or any subsequent
version published by EPA. This definition incorporates by reference EPA

Protocol.

(9) CONFIDENCE COEFFICIENT (CC)

- the 2.5 percent error confidence
coefficient for the 95 percent confidence interval of a series of t ests. The

CC is calculated as follows:

0 975

. 

### CC t S d

n 

### =

Where:

S d = Standard deviation

n = Number of data in a series of tests

t 0.975 = t

- value (see Table of t

- Values below)

Table of t

- Values*

n t 0.975 n t 0.975 n t 0.975
2 12.706 7 2.447 12 2.201

3 4.303 8 2.365 13 2.179

4 3.182 9 2.306 14 2.160

5 2.776 10 2.262 15 2.145

6 2.571 11 2.228 16 2.131

* The t

- values in this table are already corrected for n

- 1 degrees of freedom. Use n equal to the number of data points.Rule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 5 (10) C ONTINUOUS EMISSION MONITORING SYSTEM (CEMS)

- the
total combined equipment and systems required to continuously determine
air contaminants and diluent gas concentrations and/or mass emission rate
of a source effluent (as applicable). The CEMS consists of three major
subsystems: sampling interface, analyzer and data acquisition system.

(11) CONTINUOUS MONITORING

- a monitoring in which a minimum of
one measurement (e.g., concentration, mass emission, flow rate) is taken

and recorded each minute.

(12) DATA A CQUISITION SYSTEM (DAS)

- the part of the CEMS that
processes data generated by the analyzer and records the results, thus
creating a permanent record of the output signal in terms of concentration,
flow rate, and any other applicable parameter necessary to generate the
required data in units of applicable standard. The DAS consists of all
equipment such as a computer required to convert the original recorded
values to any values required for reporting.

(13) DILUENT GAS

- a gas present in a calibration g as mixture or in source
emissions that is present in quantities significantly larger than the air

contaminant.

(14 ) FULL SPAN RANGE

- the full range of values or data display output that
a monitor component is calibrated to measure.

(15 ) LINEARITY ERROR ( LE)

- the percentage error in linearity expressed in

terms of the ratio of the absolute value of the difference between the
reference value and the mean CEMS response value, to the reference

value. LE is calculated as follows:

100 × −

= R C R LE

Where :

C = Mean of the CEMS response values

R = Certified gas concentration as reference value

(16) MODIFICATION REQUIRING RECERTIFICATION

- any change to the
basic equipment, control equipment, contaminant concentration, interfering

substa nces, or CEMS that is deemed by the Executive Officer to have aRule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 6 potential for adversely affecting the ability of the CEMS to provide
accurate, precise and timely data representative of the stack emissions for
which the CEMS (or SCEMS) is required.

(17) NI NETY

- FIVE PERCENT CONFIDENCE INTERVAL

- the statistical
estimation denoting a range of values which is expected to include a true
value with a 95 percent probability.

(18) OPERATIONAL PERIOD

- a minimum period of 168 continuous hours
during which the CEMS shall operate, according to the manufacturer's
written performance and equipment specifications, without unscheduled
maintenance, repair, or adjustment.

(19) QUALITY ASSURANCE/QUALITY CONTROL (QA/QC) PLAN

- a written document in which the specific procedur es for the operation,

calibration and maintenance of a certified CEMS are described in detail,
including additional quality assurance assessments and the corrective action
system. The purpose of this plan is to ensure that the CEMS generates,

collects and reports valid data that is precise, accurate, complete, and of a
quality that meets the requirements, performance specifications, and

standards of Rules 218 and 218.1.

(20) REFERENCE METHOD (RM)

- the official test method employed by the

District to dete rmine compliance with the rules or permit conditions. A list

of reference methods is identified in Table 1.

(21) RELATIVE ACCURACY (RA)

- the absolute mean difference between
the gas concentration or emission rate determined by the CEMS and the

value deter mined by the RM plus 2.5 percent error of confidence
coefficient of a series of tests, divided by the mean of the RM tests.

(22) RELATIVE ACCURACY AUDIT (RAA)

- the RA test expressed in

terms of the ratio of the relative difference between the mean refe rence method value and the mean CEMS response value, to the mean value
determined by the reference method or applicable standard for
concentration, flow or mass emission rate. Unless otherwise specified,
RAA shall have the same specifications and require ments as the Relative
Accuracy Test Audit (RATA), except that the RAA shall require a
minimum of three data sets. When a rule requires a correction of the air
contaminant concentration to a specific O 2 or CO 2 concentration, the RA
requirement shall apply to the corrected concentration value. The RA of a
RAA data set is calculated and expressed as a percentage as follows:Rule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 7 RA r RM

RM = − × 100

Where:

RM = Mean of the values determined by the reference

method or applicable standard

r = Mean of the CEMS response values

(23) RELATIVE ACCURACY TEST AUDIT (RATA)

- the RA test expressed

in terms of the ratio of the sum of the absolute mean difference between the

CEMS

- generated data and the value determined by the applicable ref erence method or applicable standard and the absolute confidence coefficient, to
the mean of the reference method or applicable standard value for

concentration, flow or

mass emission rate. When a rule requires a

correction of the air contaminant concen tration to a specific O 2 or CO 2 concentration, the relative accuracy requirement shall apply to the

corrected concentration value. The RA of a RATA data set is calculated
and expressed as a percentage as follows:

RA d CC

RM = +

× 100

Where:

d = Absolute value of the mean difference

|CC| = Absolute value of the 95% confidence coefficient

RM = Average RM value or applicable standard

The arithmetic mean of the difference, d, of a set of data is calculated as

follows:

d

n i i n 

### d =

= 

### ∑ 1

1
Where:

i i n 

### d

= 

### ∑

1 = Algebraic sum of the individual differences d i

d i = The difference between the reference method value

and CEMS value, both in units of the applicable

standard

n = Number of data pointsRule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 8 (24) RESPONSE TI ME

- the time interval from a step change in the air
contaminant or gas diluent concentration to the time when 95 percent of
the corresponding final value is reached as displayed on the CEMS data
recorder or acquisition system. The response time is determi ned by
introducing a certified gas mixture into the CEMS upstream of the
sampling interface and as close to the probe inlet as practicable.

(25) ROUTINE MAINTENANCE

- preventive evaluation and repair (if
necessary) of CEMS performed at specified intervals to preclude system
failure. Routine maintenance may be performed as recommended by the
manufacturer or a documented standard operating procedure determined
through operating experience and approved by the Executive Officer.
Repairs to a malfunctioning sy stem are excluded from this definition.

(26) SAMPLING INTERFACE

- that part of the CEMS that performs sample
acquisition using one or more of the following operations: extraction,
physical/chemical separation, transportation or conditioning of a

representa

tive sample from a designated source.

(27) SEMI

- CONTINUOUS EMISSION MONITORING SYSTEM (SCEMS)

- the total combined equipment and systems required to semi

- continuously
determine air contaminants and diluent gas concentrations and/or mass

emission rate of a source effluent (as applicable). The SCEMS consists of
three major subsystems: sampling interface, analyzer and data acquisition
system. This class of monitoring includes but is not limited to gas
chromatography, integrated sensitized tape analyzer, other sample
integration based technologies, and time

- shared CEMS.

(28) SYSTEM BIAS

- the difference between the gas concentrations exhibited
by the CEMS when a calibration gas is introduced at a location upstream of
the sampling interface, and as close to the sampling probe inlet as
practicable, and when the same calibration gas is introduced directly to the
analyzer.

(29) SYSTEM FAILURE

- inability of the CEMS to meet the requirements of

Rule 218.1.

(30) TIME

- SHARING

- a monitoring technique where an analyzer and possibly
the associated sample conditioning system is used on more than one

source.Rule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 9 (31) ZERO CHECK

- a procedure performed to determine the response of the
CEMS to a given zero gas standard by means of injecting the zero gas into

the CEMS as close to t he probe tip as practical.

(32) ZERO DRIFT (ZD) is the change in the monitoring system
output/response over a stated period of time of normal continuous
operation when the air contaminant or diluent gas concentration at the time

of the measurements is zero . The values for ZD shall be expressed as the

ratio of the sum of the absolute value of the mean of the difference between
paired instrument response values and the absolute value of the CC, to the
full span range, calculated as a percentage as follows:

ZD d CC

S = + × 100

Where:

S = Full span range

|CC| = Absolute value of the confidence coefficient

d = Absolute value of the mean difference. The mean

difference is calculated as:

d

n i i n 

### d =

= 

### ∑ 1

1
Where:

i i n 

### d

= 

### ∑

1 = Alge braic sum of the individual differences d i

n = Number of data pairs

d i = The difference between a pair of instrument response

values (33) ZERO GAS

- a gas containing less than a specified amount of the
contaminant or diluent gas which, when periodically i njected into the
CEMS, is used to check CEMS’ response to the absence of the air
contaminant or diluent gas.

(b) Standards for New or Modified CEMS
In order to be a Certified CEMS, a CEMS subject to the provisions of Rule 218

Sections (c)(1), (d)(1)(C), (d )(1)(D)(i), (d)(2)(C) and (d)(2)(D), as applicable,
shall meet the operational requirements, performance specifications, and standards

as follows:Rule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 10 (1) Pre

- Certification Testing Requirements for New or Modified CEMS
Before any certification or relative accu racy test is performed, the CEMS
shall meet the following standards:

(A) CEMS Location

The CEMS shall be installed at a location that enables
measurements of air contaminant and diluent gas concentration, and
flow rates can be made which are representative of the stack

emissions of the source.

(B) Sampling Location
The monitoring system sampling probe tip and the reference
method sampling port locations shall be determined according to
District Method 1.1. The monitoring sampling probe shall be

located whe re a sample may be obtained which is representative of
the source emissions. Each probe shall not interfere with the other

when in use. Other locations may be chosen subject to a written
approval of the Executive Officer. If an alternate location is cho sen
which does not conform with District Method 1.1, the absence of
flow disturbance shall be demonstrated using the District method in
the source Test Manual, Chapter X, Section 1.4

- "Alternative Site
Selection Method", or 40 CFR, Part 60, Appendix A, Me thod 1,

Section 2.5

- "Alternative Measurement Site Selection Procedure",
and, the absence of stratification shall be demonstrated using the
District method in the source Test Manual, Chapter X, Section 13

-
"Determination of Gaseous Constituent Stratifi cation".
Alternatives to sampling site selection in the presence of
stratification are presented in Rule 218.1(b)(3)(C)(ii).

(C) Full Span Range (FSR)

(i) The FSR for mass emission rate, air contaminant, diluent

and flow analyzers shall be set such that a ll data points are
within 10 to 95 percent of the range.

(ii) For air contaminant monitors, the FSR shall be set between
150 and 200 percent of the concentration limit as specified
in the applicable rule or permit condition. The FSR may be

set at a value other than that specified, but no lower than
120 percent, provided that the CEMS owner or operator

demonstrates to the satisfaction of the Executive OfficerRule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 11 that the FSR will not be exceeded. Such demonstrations
may include, but not limited to, historical emissions data,
historical process information, and historical operational
information. A written approval from the Executive Officer
shall be obtained before the FSR may be modified outside of
the 150 to 200 percent of the concentration limit.

(iii) For air contaminant monitors, a multiple

- span

- range may be
required to satisfy the provisions of Sections C(i) and (ii)

above in situations where the normal concentration of the
air contaminant emitted is significantly less than the

allowable concentration lim it. The CEMS shall have the
capability to automatically change from one range to the
other as appropriate to the monitor’s measured

concentration.

(iv) For diluent monitors, the FSR shall be set such that the full
range of oxygen and carbon dioxide concen trations can be
measured. The FSR shall be set at 25.0 percent O 2 (maximum) and 1.0 percent CO 2 (minimum)
concentrations, or at a value approved by the Executive

Officer.

(v) Should any data points fall below 10 percent of the FSR,
those data points shal

l be reported according the following,
as applicable:

(I) For CEMS with certified multiple span ranges, the
owner shall report data that falls below 10.0 percent
of the higher FSR and above 95 percent of the lower
FSR, at the 10.0 percent value of the hig her FSR,

(II) In the event that any of the data points gathered by
the CEMS fall below 10.0 percent of the FSR, the
owner or operator may elect to report the
contaminant concentrations at the 10.0 percent FSR

value, or,

(III) In the event that any data p oints gathered fall below
10.0 percent of the lowest vendor guaranteed FSR

for that CEMS (defined as the lowest FSR that the
vendor guarantees to be capable of meeting allRule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 12 current certification requirements of Rule 218 and
Rule 218.1, as applicable) the ow ner or operator
may elect to use the following to measure and report

contaminant concentrations:

(a) Report data at 10.0 percent FSR value, or,

(b) Report data at actual measured value,
provided that the CEMS meets the
Supplemental and Alternative Perform ance Requirements in Attachment A.

(vi) Should any data points fall above 95 percent of FSR, the
value shall be invalid for quantification and the CEMS shall
be considered unavailable for the purposes of determining
CEMS availability percentage. All excurs ions above 95
percent of FSR and the duration of these excursions shall be
reported in the CEMS summary report as prescribed under

Rule 218(f).

(D) Strip Chart Recorder

(i) For CEMS where the strip chart recorder is used as the only

means of data recordin g, the strip chart shall have a
minimum width of at least 10 inches, a readability of 0.5%
of the span, and a minimum of 100 chart divisions.

(ii) For CEMS where the strip chart recorder is used as a back

up system or for recording data from only a single
parameter, a strip chart of lesser size than specified in
Section (D)(i) above, may be proposed in the application.

(iii) For CEMS equipped with multiple

- span ranges, the chart
recorder shall have the capability to automatically change
span, as appropriat e. (E) Data Acquisition System (DAS)

(i) The DAS shall maintain all recorded data in accordance

with Rule 218, Section (e).

(ii) For CEMS, DAS shall acquire data from monitored
parameters at least once every minute.

(iii) For SCEMS, DAS shall acquire data from monitored
parameters at least once every 15 minutes.Rule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 13 (iv) DAS acquisition rate shall be set at a constant rate such that
the data points are equally spaced.

(v) All valid data points shall be used to determine compliance
with applicable limit(s), and, for certification testing and

RATA(s).

(vi) DAS sample acquisition rate during certification and
RATA(s) shall be the same as the DAS sample acquisition
rate during normal CEMS, or SCEMS, operation.

(F) Operational Period
The operational period before any certification tests shall be a

minimum of 168 continuous hours.

(2) Certification Requirements and Performance Specifications for New or

Modified CEMS
Rule 218(c)(1) provides that a series of certification tests shall be
performed to demonstrate the accep tability of CEMS performance. The
requirements and specifications in conducting initial certification tests

follow:

(A) Calibration Error (CE) Testing

The 24

- Hour CE test shall be performed at the low and high ranges,
namely 0 to 20 and 80 to 100 percent of FSR, respectively. CE
specifications shall be less than or equal to:

(i) 2.5 percent of the FSR for all analyzers, and

(ii) 3.0 percent of the FRS of the analyzer, for flow monitors,
when an electronic calibration check is applicable.

The 24

- hour CE test shall be performed once each day as close to

24

- hour intervals as practicable, with a total of eight (8)
consecutive tests performed. The CE specifications shall not be
exceeded on any of the tests during the entire testing period.

(B) Analyzer Encl

osure (i) The analyzer shall be contained in an environmentally
controlled enclosure. An alarm and recording device shall be
incorporated into the system to alert the operator to make
corrective action should the analyzer exceed the

manufacturer’s recommen ded specifications for temperature

drift.Rule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 14 (ii) Alternatively, the owner or operator of the CEMS may
choose to perform the 2

- hour CE tests in

- lieu of meeting
the analyzer enclosure requirement in Section(b)(2)(B)(i).

The 2

- hour CE test shall be performed on ce every two

hours as close to 2

- hour intervals as practicable, with total
of thirteen consecutive tests performed. The 2

- hr CE test
shall be performed when ambient temperature is expected to
vary diurnally at least 30 o F. The test shall be performed at

t he low and high ranges of FSR, namely 0 to 20 and 80 to
100 percent, respectively. The specifications in Sections
(b)(2)(A)(i) and (ii) shall apply to 2

- hour CE.

(iii) The owner or operator of the CEMS may qualify for an
exemption from Section(b)(2)(B)(i) to provide
environmental controls for the analyzer enclosure by
demonstrating, to the satisfaction of the Executive Officer,

that the CEMS is located:

(I) In a geographic area where seasonal high and low
temperatures do not exceed the operational

temperatu re specifications for the analyzer,

(II) In a geographic area where monthly maximum
temperature variation is less than 30 o F for all months
of the year, and

(III) The CEMS is located in a site that is protected from
radiation and convection heating sources.

(C) Relative Accuracy
RATA shall be performed for raw contaminant concentration, and if
applicable, for corrected concentration, emission rate, O 2 concentration, CO 2 concentration analyzers, and stack and fuel

flow monitors. There shall be a minimum of ni ne sets of test data
generated. If the number of tests exceeds nine sets, data may be
discarded if it is identified as an outliers by the technical guidance
set forth by the Executive Officer, or for valid reasons (e.g.,
process upsets, CEMS malfunction, e tc.) which must be
substantiated with appropriate documentation and subject to
approval by the Executive Officer. All data collected shall be

submitted to the Executive Officer.Rule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 15 The CEMS shall meet the following RA performance specifications:

(i) Less than

or equal to 20.0 percent of the mean value of the
reference method for pollutant concentrations, or the de

minimus concentration as follows, whichever is greater:

Pollutant De minimus Concentration

NOx 1.0 ppm

SO 2 2.0 ppm

CO 2.0 ppm

Reduced Sulfur Com

pounds 4.0 ppm
(ii) Less than or equal to 10.0 percent of the mean value of the

reference method for diluent concentrations, or the de
minimus value of 1.0 percent O 2 , whichever is greater.

(iii) Less than or equal to 15.0 percent of the mean value of the

reference method for flow monitors, or the de minimus
value equivalent to a calculated volumetric flow rate based
on 2 feet per second stack gas velocity for cases where the
mean stack gas velocity obtained by the reference method

test is less than 15 fee t per second.

(iv) Less than or equal to 20.0 percent of the mean value of the

reference method for mass emission rates, or the de minimus
value equivalent to a calculated mass emission rate based on
2 feet per second stack gas velocity for cases where the
mean stack gas velocity obtained by the reference method
test is less than 15 feet per second.
The relative accuracy requirement may be met if the average

of the differences between the CEMS measured data and
the reference method test data plus the confid ence coefficient is less than or equal to the relative accuracy de

minimus value.

(3) Relative Accuracy Test Requirements for New or Modified CEMS
Within fourteen days of, or during all relative accuracy tests, the CEMS
shall meet the following requiremen ts, except those that may be waived as

allowed in Rule 218.1, Section (b)(4)(C):

(A) Response Time
The response time for CO CEMS shall not exceed 1.5 minutes
except where there is a technical limitation, in which case theRule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 16 response time shall be 5 minutes. The response time for all other
CEMS and flow monitors, as applicable, shall not exceed 5 minutes.

(B) Calibration Error
The CE testing requirements are specified in Section (b)(2)(A).

(C) Concentration Stratification

(i) The owner or operator shall demo nstrate the absence of
stratification through testing performed according to the
method in Chapter X, Section 13

- “Non

- Standard Methods
and Techniques”, of the District Source Testing Manual.

The number of tests shall be determined as follows:

(I) Test(s ) shall be conducted at one load level if the
owner or operator demonstrates to the satisfaction
of the Executive Officer that the equipment operates
within a 20 percent load range for at least 80 percent

of the time;

(II) Test(s) shall be conducted at tw o different load
levels if the owner or operator demonstrates to the

satisfaction of the Executive Officer that the
equipment operates within a 50 percent load range
for at least 80 percent of the time; or,

(III) Test(s) shall be conducted at three differ ent load
levels if the equipment operates outside of the

criteria in Sections (b)(1)(C)(i)(I) and (II).

The absence of stratification is considered verified if
the difference between the highest measured

concentration (time normalized) and the lowest

meas ured concentration (time normalized) divided
by the average measured concentration (time
normalized), when expressed as a percentage, is less
than or equal to 10 percent. Upon verification of the
absence of stratification, the owner or operator may
positio n the CEMS sampling probe at any point
within the stack with the exception of those points
that are adjacent to the stack wall. The CEMS
sampling probe should be located in the stack at

least one

- third of the stack diameter. The RM forRule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 17 RATA may be conduc ted at a single point within the
stack that is not adjacent to the stack wall and does
not interfere with the sampling and the operation of
the facility CEMS.

(ii) Should testing demonstrate the presence of stratification,
the owner or operator may elect o ne of the following

alternatives:

(I) If the stratification is greater than 10 percent but the
difference between the highest measured

concentration (time normalized) and the lowest

measured concentration (time normalized) is less
than or equal to 1.0 ppm

v: (a) Then the CEMS sampling probe may be
located at any point within the stack except
any points that is adjacent to the stack or
adjacent to the highest measured

concentration (time normalized) and the

lowest measured concentration (time

normalized), o r (b) If it is not possible to avoid using a point
adjacent to either the highest measured

concentration (time normalized) or the

lowest measured concentration (time
normalized), then locate the CEMS sampling
probe such that the placement minimizes the

di fference between the concentration at the
proposed probe location and the
concentration at the point of highest

measured concentration (time normalized) or

the lowest measured concentration (time

normalized).

(II) Determine a representative CEMS probe loca tion
such that the following criteria are met:

(a) all traverse point concentrations are within
10.0% of the average of all traverse point

concentrations (time normalized), or, theRule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 18 difference is less than or equal to 1.0 ppm,
whichever is greater, and

(b ) there exists at least one traverse point

concentration (Xr), not located next to the
stack or duct wall, that is less than or equal
to 10.0% each adjacent traverse point

concentration of Xr, or the difference is less
than or equal to 1.0 ppm, whichever i s greater, and,

(c) the CEMS probe is located at (or as near as
practical) Xr with minimum adjacent traverse
point concentration fluctuations as

determined in section (ii)(II)(b), above.

(III) Determine a representative multiple point sampling
configurati

on as approved by the Executive Officer,
following the guidance document by Emission

Measurement Technical Information Center,

"Evaluation Procedure for Multi

- Hole Sample

Probes" (EMTIC GD

- 031)

(IV) Modify the stack and/or CEMS sampling probe

location an d retest for the absence of stratification.

(D) Cyclonic Flow
The owner or operator shall perform tests to verify the absence of
cyclonic flow for the CEMS and reference method sampling probes.
The cyclonic flow test shall be required when measuring mass
emission rates and shall be performed according to the District
method in the Source Test Manual, Chapter X: Non

- Standard
Methods and Techniques following the testing conditions of
Section (3)(C)(i)(I), (II) or (III), as applicable.

(E) Interference

The ow ner or operator shall perform tests to verify the absence of
sampling, analytical and flow interference, as applicable.

(F) Linearity Error

LE tests shall be performed at the low, middle and high ranges of
concentration, namely 20 to 30, 50 to 60, and 80 t o 100 percent.
Each calibration gas shall be introduced into the CEMS three times.Rule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 19 The same gas shall not be used twice in succession. LE shall be less
than or equal to 5.0 percent of the calibration gas concentration.
(G) Multiple

- Span

- Range

For CEMS that have multiple

- span range, all certification tests
shall be performed at the lowest range. Except for RA and
interference tests, all other certification tests shall be performed on
other ranges.

(4) Operational Requirements and Performance Specifica tions for New or

Modified CEMS
After final approval, the CEMS shall be subsequently operated and
maintained according to the following requirements and specifications:

(A) 24

- Hour CE
CE tests shall be performed once each day as close to 24 hour

intervals a s practicable at the low (0 to 20 percent) and high (80 to
100 percent) ranges of concentration. CE test results which are
greater than the limits specified in Sections (b)(2)(A)(i) and (ii), but
less than or equal to 5.0 percent of the full span range sh all be
addressed by QA/QC Plan remediation. The CEMS shall be

deemed out

- of

- control during such period when any CE test result
is greater than the specified limits and greater than 5.0 percent of
the full span range, until the CE test meets the specificat ions. All
data generated by the CEMS during an out

- of

- control period shall

be deemed invalid but shall not be deleted or excluded from the

records or database.

(B) System Bias Test
A system bias shall be conducted every 12 months in conjunction

with relat ive accuracy audit required under Rule 218 Section
(b)(4)(C). The CEMS system bias shall not exceed + 5.0 percent of
the full span range for contaminant analyzers. In addition, the
owner or operator shall include in the facility QA/QC Plan, criteria

for excessive drift (e.g. control limits on cumulative drift) and
appropriate diagnostic techniques to identify sources of analyzer
drift and system bias when control limits are exceeded.

(C) Relative Accuracy Testing
RATA and RAA, as applicable, shall be perf ormed at least once
every 12 months. The test shall be completed annually no later thanRule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 20 the end of the calendar quarter in which the date of the original
certification test was performed. During any relative accuracy tests

after CEMS certification, the ow ner or operator may request a
waiver from stratification, cyclonic flow, and/or interference
requirements in Sections (b)(3)(C), (D) and (E), respectively, by
submitting to the Executive Officer, for approval, any applicable
documentation or previous test or historical data that meets the
stratification, cyclonic flow, and/or interference requirements.

(D) Cylinder Gas Audit (CGA)
A CGA shall be performed every calendar quarter but in no more
than three quarters in succession. The CGA shall be conducted

ac cording to the provisions of 40 CFR 60, Appendix F. The audit
gases shall be according to the certification requirements of Rule

218.1.

(E) The Executive Officer may require recertification of the CEMS if
the annual availability percentage is below 95 perc ent. Annual
CEMS availability percentage calculations will be based on the year
ending on the last day of the calendar quarter in which the CEMS
was originally certified.

(F) The owner or operator of a CEMS that requires moisture
correction in reporting f low and concentration shall measure and
monitor moisture in the stack gas used for emission data
calculations in accordance with the written technical guidance
document set forth by the Executive Officer. Alternatively, with
Executive Officer approval, fo r equipment whose moisture source
is only from fuel combustion, the operator may calculate the
moisture content using fuel properties and ambient air humidity
data or, for processes that saturate the exhaust gas with moisture,
such as a wet scrubber system , the operator may use the saturation
temperature for moisture content data.

(c) Standards for Existing CEMS
In order to be a Certified CEMS, a CEMS subject to the provisions of Rule 218
Sections (d)(1) and (d)(2), shall meet the following operational requ irements and
performance specifications, and the standards of Rule 218.1 Section (d):

(1) Performance Specifications for Existing Gaseous Air Contaminant CEMSRule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 21 Parameter Specifications

(A) Operational Period Greater than or equal to 168 hours

(B) Calibra

tion Error Less than or equal to 5 percent of

the calibration gas value

(C) Response Time Less than or equal to 10 minutes

(D) Zero Drift (2

- hour) Less than or equal to 2 percent of
FSR

(E) Zero Drift (24

- hour) Less than or equal to 2 percent of
FSR

(F ) Calibration Drift (2

- hour) Less than or equal to 2 percent of
FSR

(G) Calibration Drift (24

- hour) Less than or equal to 2.5 percent
of FSR.

(H) Relative Accuracy Less than or equal to 20 percent of
the mean value of the RM test data, or, less than or e qual to 10 percent of the allowed concentration, whichever is
greater

(2) Performance Specifications for Existing Diluent Gas CEMS

Parameter Specifications

(A) Operational Period Greater than or equal to 168 hours

(B) Calibration Error Less than or equal to 5 percent of the calibration gas value

(C) Response Time Less than or equal to 10 minutes

(D) Zero Drift (2

- hour) Less than or equal to 0.4 percent
CO 2 or O 2

(E) Zero Drift (24

- hour) Less than or equal to 0.5 percent
CO 2 or O 2

(F) Calibration Drift (2

- hour) Less than or equal to 0.4 percent
CO 2 or O 2

(G) Calibration Drift (24 hour) Less than or equal to 0.5 percent
CO 2 or O 2Rule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 22 (3) Full Span Range for Existing CEMS
The instrument FSR shall be equivalent to approximately 200 percent of

the concen tration limit as specified in the applicable rule, or at a value
approved by the Executive Officer. Oxygen and carbon dioxide instrument
full span readings shall be such that the full range of concentrations

encountered can be measured.

(4) Cycle of Opera

tion for Existing CEMS
The CEMS shall complete a minimum of one cycle of operation (sampling,
analyzing and data recording), for each successive 15 minute period.

(d) Standards, Specifications and Requirements for New, Modified and Existing

CEMS:

(1) Calib ration Gas

(A) Calibration gas mixtures, as defined in Rule218.1 (a)(8), shall be
manufactured, analyzed and certified in accordance with the “EPA
Traceability Protocol for Assay and Certification of Gaseous

Calibration Standards”

- EPA

- 600/R97/121, Septem ber 1997
Revision (EPA Protocol). The certification period and
recertification requirements, as applicable, shall be according to the

EPA Protocol.

(B) For gas calibration standards not explicitly covered by the EPA
Protocol, the CEMS owner or operator shall submit the gas
manufacturer's alternative certification protocol for the specific
compound or compounds.

(i) The procedures of the EPA Protocol shall be used for gas
calibration standards not explicitly covered therein, except
that the gas manufact urer must identify a recertificaton
period and submit data documenting the applicability of this
period. The gas manufacturer may submit alternative
performance standards for certification and recertification,
based on supporting technical data also provi ded by the
manufacturer. This alternative shall be subject to the
approval of Executive Officer.

(ii) If there is no existing National Institute of Standards and
Technology (NIST) standard for the measured parameter,
the gas manufacturer may submit an al ternative referenceRule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 23 standard and the supporting technical data that define the
stability, accuracy, and precision of the alternative reference
standard. This alternative shall be subject to the approval of

Executive Officer.

(iii) The CEMS owner or operato r may submit an alternative
protocol to the EPA Protocol, provided that the CEMS
owner or operator demonstrates through supporting
technical data that the procedures therein are not applicable
to the constituent in the calibration gas standard being

certif ied. This alternative shall be subject to the approval of

Executive Officer.

(C) Compressed and/or filtered air, such as instrument air, may also be
used in lieu of oxygen span gas provided that the CEMS owner or
operator demonstrates, to the satisfaction of the Executive Officer,
that it is of equivalent quality to the calibration gas standards above.
As part of such documentation, the owner or operator shall include
in their QA/QC plan the process or operation in producing such
compressed and/or filtered air and periodically checking that
compressed air and/or filtered air continues to meet the calibration
gas standards.

(2) Zero Gas
Zero gases used shall meet the following criteria:

(A) For gaseous air contaminant monitors, the zero gas shall be

certifie d by the manufacturer to contain no more than 0.1 ppm of
the air contaminant analyzed by the subject monitor or 1.0 percent
of the applicable standard, whichever is less.

(B) For carbon monoxide monitors, the zero gas shall be certified by

the manufacturer to contain less than 0.5 ppm carbon monoxide or
1.0 percent of the applicable standard, whichever is less.

(C) For carbon dioxide and oxygen monitors, the zero gas shall be
certified by the manufacturer to contain less than 1.0 ppm carbon
dioxide or oxyge n. (D) Compressed and/or filtered air, such as instrument air, may also be
used in lieu of zero gas provided that the CEMS owner or operator

demonstrates, to the satisfaction of the Executive Officer, that it is
of equivalent quality to the above zero gas standards. As part ofRule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 24 such documentation, the owner or operator shall include in their
QA/QC plan the process or operation in producing such
compressed and/or filtered air and periodically checking that
compressed air and/or filtered air continues to meet the zero gas

standards.

(3) Automatic Calibration Data
If automatic adjustments to the monitor settings are made, conduct the
calibration tests in a way that the magnitude of the adjustments can be

determined and recorded.

(4) F

- Factors
The owner or opera

tor shall use in the CEMS calculations the Fd factors
listed in 40 CFR Part 60, Appendix A, Method 19, Table 19

- 1, as
applicable. When alternative fuels are fired, the owner or operator shall
submit data to develop Fd factors and obtain Executive Officer approval.

(5) NO 2 to NO Conversion Efficiency
The conversion efficiency tests shall be conducted according to the
requirements of District Method 100.1. The value for the NO 2 gas shall be
greater than or equal to the maximum expected or recorded NO 2 and
greater than or equal to 20 percent of the FSR.

(e) Time

- Sharing Requirements

A time

- shared CEMS for which an application is submitted after [date of adoption]
shall meet all of the performance specifications as well as the following
requirements:

(1) All

sources shall have mutually compatible range(s) of air contaminant
gases at all times.

(2) Each source shall have a data

- reading period, at a minimum, equal to three
times the longest response time of the system. For shared systems the
response time is m

easured at the input or probe at each source. A
demonstration of response time for each source shall be made during
certification testing. Data are not to be collected following a switch of
sample sources until a period of time equal to one response time has
passed.

(3) The CEMS shall be capable of performing and recording zero and span
calibrations at each source, including the calibration factors and correction
values before and after every automatic calibration.Rule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 25Rule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 26 Table 1
REFERENCE METHODS
RULE 218.1

District Method 1.1

- Sample and Velocity Traverses for Stationary Sources

District Method 1.2

- Sample and Velocity Traverses for Stationary Sources with Small
Stack or Ducts

District Method 2.1

- Determination of Stack Gas Velocity and Volumetric Flow Rate (S

- type Pitot tube)

District Method 2.2

- Direct Measurement of Gas Volume through Pipes and Small Ducts

District Method 2.3

- Determination of Gas Velocity and Volumetric Flow Rate from
Small Stacks or Ducts

District Method 3.1

- Gas Analysis for Dry Molecular Weight and Excess Air

District Method 4.1

- Determination of Moisture Content in Stack Gases

District Method 6.1

- Determination of Sulfuric Acid and Sulfur Oxides from Stationary
Sources

District Method 7.1

- Determination of Nitroge n Oxide Emissions for Stationary Sources

District Method 100.1

- Instrumental Analyzer Procedures for Continuous Gaseous Emission Sampling

District Method 307.91

- Determination of Sulfur in a Gaseous Matrix

EPA Method 6

- Determination of Sulfur Dioxid e Emissions from Stationary Sources

EPA Method 19

- Determination of Sulfur Dioxide Removal Efficiency and Particulate, Sulfur Dioxide and Nitrogen Oxides Emission Rates from Electric Utility Steam Generator (40 CFR Part 60 Appendix A)

ASTM Method D 4294 or D 2622

- 82

- Determination of Sulfur in Liquid FuelsRule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 27 ATTACHMENT A

SUPPLEMENTAL AND ALTERNATIVE CEMS PERFORMANCE REQUIREMENTS

A. Applicability of Supplemental and Alternative Performance Requirements

The CEMS operator who elects (or who may be r equired) to measure concentrations that fall below 10 percent of the lowest vendor guaranteed full scale span range, shall satisfy the performance requirements as specified in Table A

- 1
listed below.

TABLE A

- 1

Alternative Performance Requirement(s)

CEM S Certified per
Rule 218.1 Performance Requirement(s)

Yes or No LLSR/BFD HLSR/BFD LLR/BFD LLCE

Yes x + x
No x x + x

1. + (plus) denotes an additional performance requirement that shall be conducted if the mandatory performance requirement(s) cannot be met.

2. If the concentration of the CEMS is such that the specifications for the low level spike recovery/bias factor determination cannot be met, the Facility Permit
holder shall conduct a low level RATA/bias factor determination.

3. Abbreviations used in this Attachment are:

Low Level Spike Recovery/Bias Factor Determination (LLSR/BFD) High Level Spike Recovery/Bias Factor Determination (HLSR/BFD) Low Level RATA/Bias Factor Determination (LLR/BFD) Low Level Calibration Error (LLCE)
Relative Ac curacy Test Audit (RATA) Relative Accuracy (RA) National Institute of Standards Traceability (NIST)

B. Test Definitions, Performance Specifications and Test Procedures

This section explains in detail how each performance requirement is to be conduct ed.

1. Low Level Calibration Error The low level calibration error test is defined as challenging the CEMS (from probe to monitor) with certified calibration gases (e.g., NO in N2) at three levelsRule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 28 in the 0

- 20 percent full span range. Since certified gas mixtures or standards may not be available at the concentrations required for this test, gas dilution systems may be used, with District approval, if they are used according to either District or EPA protocols as specified in Rule 218.1, for the verificat ion of gas dilution systems in the field. The CEMS high

- level calibration gas may be diluted for the purpose of conducting the low level calibration error test.

a. Performance Specifications Introduce pollutant concentrations at approximately the 20 per cent, 10 percent, and 5 percent of full span levels through the normal CEMS calibration system. No low level calibration error shall exceed 2.5 percent of full scale span.

b. Testing Procedures
i. Perform a standard zero/span check; if zero or span che ck exceeds 2.5 percent full span, adjust monitor and redo zero/span check.

ii. After zero/span check allow the CEMS to sample stack gas for at least
15 minutes.

iii. Introduce any of the low level calibration error standards through the
CEMS calibratio n system.

iv. Read the CEMS response to the calibration gas starting no later than three system response times after introducing the calibration gas; the CEMS response shall be averaged for at least three response times and for no longer than six respons e times.

v. After the low level calibration error check allow the CEMS to sample stack gas for at least 15 minutes.

vi. Repeat steps iii through v until all three low level calibration error checks are complete.

vii. Conduct post test calibration and zero checks.

2. Spike Recovery and Bias Factor Determinations Spiking is defined as introducing known concentrations of the pollutant of interest (e.g., gas standard to contain a mixture of NO and NO2 is representative
of the ratio of NO and NO2 in sta ck gas) and an appropriate non

- reactive, non

condensable and non

- soluble tracer gas from a single cylinder (EPA Protocol as specified in Rule 218.1 or NIST traceable to 2 percent analytical accuracy if no EPA Protocol is available) near the probe and upstr eam of any sample conditioning systems, at a flow rate not to exceed 10 percent of the total sample gas flow rate. The purpose of the 10 percent limitation is to ensure that the gasRule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 29 matrix (water, CO2, particulates, interferences) is essentially the same as the stack gas alone. The tracer gas is monitored in real time and the ratio of the monitored concentration to the certified concentration in the cylinder is the dilution factor. The expected pollutant concentration (dilution factor times the
certified pollutant concentration in the cylinder) is compared to the monitored pollutant concentration.

3. High Level Spike Recovery/Bias Factor Determination The high level spike recovery/bias factor determination is used when it is technologically not possibl e to certify the CEMS per the standard Rule 218.1 requirements. The spiking facility/interface shall be a permanently installed part of the CEMS sample acquisition system and accessible to the Executive Officer as well as the CEMS operator.

a. Performanc e Specifications
The CEMS shall demonstrate a RA < 20 percent, where the spike value is used in place of the reference method in the normal RA calculation, as
described below.
b. Testing Procedures
i. Spike the sample to the CEMS with a calibration stand ard containing the pollutant of interest and CO or other non

- soluble, non

- reacting alternative tracer gas (alternative tracer gas) at a flow rate not to exceed 10 percent of the CEMS sampling flow rate and of such concentrations as to produce an expected 4 0

- 80 percent of full scale span for the pollutant of interest and a quantifiable concentration of CO (or alternative tracer gas) that is at least a factor of 10 higher than expected in the unspiked stack gas. The calibration standards for both pollutants of interest and CO (or alternative tracer gas) must meet requirements

ii. Monitor the CO (or alternative tracer gas) using an appropriate continuous (or semi

- continuous if necessary) monitor meeting the requirements of Method 100.1 and all data falling wi thin the 10

- 95 percent full scale span, and preferably within 30

- 70 percent full scale

span.

iii. Alternate spiked sample gas and unspiked sample gas for a total of nine runs of spiked sample gas and ten runs of unspiked sample gas. Sampling
times shoul d be sufficiently long to mitigate response time and averaging
effects.

iv. For each run, the average CEMS reading must be between 40 percent full scale span and 80 percent full scale span. If not, adjust spiking as necessary and continue runs, but expe cted spike must represent at least 50 percent of the total pollutant value read by the CEMS.Rule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 30 v. Calculate the spike recovery for both the pollutant and the CO (or alternative tracer gas) for each run by first averaging the pre

- and post

spike values for each run and subtracting that value from the spiked value to yield nine values for recovered spikes.

vi. Using the CO (or alternative tracer gas) spike recovery values for each run and the certified CO (or alternative tracer gas) concentration,
calculate the dilution ratio for each run. Multiply the certified pollutant concentration by the dilution factor for each run to determine the expected diluted pollutant concentrations. Using the expected diluted concentrations as the "reference method" value, ca lculate the Relative Accuracy. The RA shall be < 20 percent.

4. Low Level Spike Recovery/Bias Factor Determination
The low

- level spike recovery/bias factor determination is used to determine if a significant bias exists at concentrations near the 10 per cent full scale span level. The spiking facility/interface shall be a permanently installed part of the CEMS sample acquisition system and accessible to the Executive Officer staff as well as the CEMS operator.

a. Performance Specifications
There are no pass/fail criteria with respect to the magnitude of the percent relative accuracy. There are performance criteria for the range of concentration on the CEMS the extent to which the spike must be greater than the background pollutant level.

b. Testi ng Procedures
i. Spike the sample to the CEMS with a calibration standard containing the pollutant of interest and CO or other non

- soluble, non

- reacting alternative tracer gas (alternative tracer gas) at a flow rate not to exceed 10 percent of the CEMS s ampling flow rate and of such concentrations as to produce an expected 10

- 25 percent of full scale span for the pollutant of interest and a quantifiable concentration of CO (or alternative tracer gas) that is at least a factor of 10 higher than expected

in the unspiked stack gas. The calibration standards for both pollutants of interest and CO (or alternative tracer gas) must meet Rule 218.1 requirements.

ii. Monitor the CO (or alternative tracer gas) using an appropriate continuous (or semi

- continuous i f necessary) monitor meeting the requirements of Method 100.1 and all data falling within the 10

- 95 percent full scale span, and preferably within 30

- 70 percent full scale

span.Rule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 31 iii. Alternate spiked sample gas and unspiked sample gas for a total of nin e runs of spiked sample gas and ten runs of unspiked sample gas. Sampling times should be sufficiently long to mitigate response time and averaging
effects.

iv. For each run, the average CEMS reading must be below 25 percent full scale span and > 10 pe rcent full scale span. If not, adjust spiking as necessary and continue runs; but expected spike must represent at least 50 percent of the total pollutant value read by the CEMS.

v. Calculate the spike recovery for both the pollutant and the CO (or
alt ernative tracer gas) for each run by first averaging the pre

- and post

spike values for each run and subtracting that value from the spiked value to yield nine values for recovered spikes.

vi. Using the CO (or alternative tracer gas) spike recovery valu es for each run and the certified CO (or alternative tracer gas) concentration, calculate the dilution ratio for each run. Multiply the certified pollutant concentration by the dilution factor for each run to determine the expected diluted pollutant conce ntrations. Using the expected diluted concentrations as the "reference method" value, calculate the Relative Accuracy as specified in Rule 218.1. If the average difference is less than the confidence coefficient then no low level bias factor is applied. If the average difference is greater than the confidence coefficient and the average expected spike is less than the average CEMS measured spike, then no low level bias factor is applied. If the average difference is greater than the confidence coefficie nt and the average expected spike is greater than the average CEMS measured spike, then a low level bias factor equal to the absolute value of the average difference is added to data reported at or below the 10 percent of full scale span.

5. Low Level RA TA/Bias Factor Determination using Enhanced Reference
Method 6.1 A low level RATA/bias factor determination is designed to determine if there exists a statistically significant bias at low level concentrations. It consists of
nine test runs that measure the stack concentration and the CEMS concentration concurrently.

a. Performance Specifications There are no pass/fail criteria with respect to the magnitude of the percent relative accuracy. There are performance criteria for the special RATA with resp ect to the reference method and range of concentration on the
CEMS.Rule 218.1 (Cont.) (Adopted May 14, 1999)

218.1

- 32 b. Testing Procedures
The reference method for the low level RATA/bias factor determination is
Method 100.1
i. Perform a minimum of nine runs of low level RATA for CEMS versus
the refe rence method at actual levels (unspiked).

ii. The full scale span range for the reference method shall be such that all
data falls with 20

- 95 percent of full scale span range.

iii. The reference method shall meet all Method 100.1 performance
criteria

.

iv. Calculate the average difference (d = CEMS

- reference method, ppm) and confidence coefficient (cc = statistical calculated, ppm).

v. If d > 0 then the bias = 0 ppm; if d < 0 and |d| > cc then bias = d; if d < 0 and |d| < cc then bias = 0 ppm.

C. Testing Frequency For each CEMS, perform the aforementioned performance requirements once a year thereafter. These annual assessments shall be completed within six months of the end of the calendar quarter in which the CEMS was originally certified.