(Adopted May 14,1999) 

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 required) 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) 

1. + (plus) denotes an additional performance requirement that shall be conducted 

if the mandatory performance requirement(s) cannot be met. 

Yes 

No 

2. If the concentration of the CEMS is such that the specifications for the low level 

spike recoveryhias factor determination cannot be met, the Facility Permit 

holder shall conduct a low level RATAhias factor determination. 

3. Abbreviations used in this Attachment are: 

x 

x 

Low Level Spike RecoveryA3ias Factor Determination (LLSR.5FD) 

High Level Spike RecoveryA3ias Factor Determination (HLSR.5FD) 

Low Level RATABias Factor Determination (LLmFD) 

Low Level Calibration Error (LLCE) 

Relative Accuracy Test Audit (RATA) 

Relative Accuracy (RA) 

National Institute of Standards Traceability PIST) 

B. Test Definitions, Performance Specifications and Test Procedures 

x 

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

conducted. 

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 levels 

+ 

+ 

Rule 218.1 - 1 

x 

x 
RULE 218.1, ATTACHMENT A (Cont.) (Adopted May 14,1999) 

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 21 8.1, for the verification 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 percent, 10 

percent, and 5 percent of 111 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 zerolspan check; if zero or span check exceeds 2.5 

percent full span, adjust monitor and redo zerolspan check. 

ii. After zerolspan 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 calibration 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 response 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 Recoverv 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 stack gas) and an appropriate non-reactive, noncondensable and non-soluble tracer gas from a single cylinder (EPA Protocol as 

specified in Rule 21 8.1 or NIST traceable to 2 percent analytical accuracy if no 

EPA Protocol is available) near the probe and upstream 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 gas 

Rule 2 18.1, Attachment A - 2 
RULE 218.1, ATTACHMENT A (Cont.) (Adopted May 14,1999) 

matrix (water, C02, 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 Recoverv1Bia.s Factor Determination 

The high level spike recovery/'bias factor determination is used when it is 

technologically not possible to certify the CEMS per the standard Rule 21 8.1 

requirements. The spiking facilitylinterface 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. Performance Specifications 

The CEMS shall demonstrate a RA 5 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 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 sampling flow rate and of such concentrations 

as to produce an expected 40-80 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 

. . 

11. 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 within 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 should 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 expected spike must represent at least 

50 percent of the total pollutant value read by the CEMS. 

Rule 2 18.1, Attachment A - 3 
RULE 218.1, ATTACHMENT A (Cont.) (Adopted May 14,1999) 

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 postspike 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, calculate the Relative 

Accuracy. The RA shall be 5 20 percent. 

4. Low Level Svike Recovew/Bias Factor Determination 

The low-level spike recoveryhias factor determination is used to determine if a 

significant bias exists at concentrations near the 10 percent full scale span level. 

The spiking facilitylinterface 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 passlfail 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 xust be greater 

than the background pollutant level. 

b. Testing 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 sampling 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 if 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 2 18.1, Attachment A - 4 

-- --.---" ---.-.-.-----. - -- -- ---- 
RULE 218.1, ATTACHMENT A (Cont.) (Adopted May 14,1999) 

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 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 percent 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 

alternative tracer gas) for each run by first averaging the pre- and postspike 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, 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 coefficient 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 RATA/Bias Factor Determination using Enhanced Reference 

Method 6.1 

A low level RATAlbias 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 passlfail criteria with respect to the magnitude of the percent 

relative accuracy. There are performance criteria for the special RATA 

with respect to the reference method and range of concentration on the 

CEMS. 

Rule 2 18.1, Attachment A - 5 

---> - . - - - --- 
RULE 218.1, ATTACHMENT A (Cont.) (Adopted May 14,1999) 

b. Testing Procedures 

The reference method for the low level RATAhias factor determination is 

Method 1 00.1 

. i. Perform a minimum of nine runs of low level RATA for CEMS versus 

the reference 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. Ifd>Othenthebias=Oppm;ifd<Oand(d(>ccthenbias=d;ifd< 

0 and Id1 < 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. 

Rule 21 8.1, Attachment A - 6 

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