8. Filterable PM Monitoring

We provided several monitoring options for the filterable 

PM standard in the final rule, including quarterly stack 

testing, PM CEMS, and PM continuous parameter monitoring system 

(PM CPMS) with annual testing. For many reasons, including 

continued use of already-installed instruments on some EGUs, 

direct (as opposed to parametric) measurement of the pollutant 

of concern, and continuous feedback for process control, we 

believe that many EGU owners or operators will choose to use PM 

CEMS to monitor the proposed filterable PM limit.

We solicit comment on whether to retain the quarterly stack 

testing compliance option, as this option may not be necessary 

because continuous, direct measurement of filterable PM or a 

correlated parameter is available and likely to be used by most 

sources to monitor compliance with the revised standard. With 

respect to the PM CPMS compliance option for new EGUs, we 

considered three ways to establish an operating limit based on 

emissions testing. The first way would allow an EGU owner or 

operator to use the highest parameter value obtained during an 

individual emissions test when the result of that individual 

test was below the limit as the operating limit. The second way 

would allow an EGU owner or operator to use the average 

parameter value obtained from all runs pertaining to an 
individual emissions test as the operating limit. The third way,

would allow an EGU owner or operator whose PM emissions as 

demonstrated during performance testing do not exceed 75 percent 

of the PM emissions limit to set his PM CPMS operating limit by 

linearly scaling the average operating value obtained during all 

the runs to be equivalent to the value at 75 percent of the 

limit; an EGU owner or operator whose PM emissions as 

demonstrated during performance testing exceed 75 percent of the 

PM emissions limit would establish his operating limit as a 30-

day rolling average equal to the average PM CPMS values recorded 

during performance testing. Such an approach would prevent 

unnecessary retests for EGUs with low PM emissions.

Even though this rule proposes the third way, we solicit 

comments on the appropriateness of any of the three ways to 

establish a PM CPMS operating limit for new EGUs.

In addition, this rule proposes to require emissions 

testing after each exceedance of the operating limit for new 

sources. This rule proposes a number of consequences if the PM 

monitoring parameter is exceeded. First, the EGU owner or 

operator will have 48 hours to conduct an inspection of the 

control device(s) and to take action to restore the controls to 

proper operation, if necessary, and 45 days to conduct a Method 

5 compliance test under the same operating conditions to verify 

ongoing compliance with the filterable PM limit. Within 60 days, 
the EGU owner or operator will have to complete the emissions 

sampling, sample analyses, and verification that the EGU is in 

compliance with its emissions limit, as well as having to 

determine an operating limit based on the PM CPMS data collected 

during the performance test. The EGU owner or operator would 

then compare the recalculated operating limit with the existing 

operating limit and, as appropriate, adjust the numerical 

operating limit to reflect compliance performance. Adjustments 

could include applying the most recently established value or 

combining the data collected over multiple performance tests to 

establish a more representative value. The EGU owner or operator 

would then apply the reverified or adjusted operating limit 

value from that time forward.

Second, this rule proposes to limit the number of exceedances of 

the site-specific CPMS limit leading to follow-up performance 

tests in any 12 month process operating period and that an 

excess of this number be considered a violation of the 

standard. This presumption of violation could be rebutted by 

the EGU owner or operator, but would require more than a 

Method 5 test as a basis for the rebuttal (e.g., results of 

physical inspections would also need to be included). This 

additional information is necessary since a Method 5 test 

could not be conducted during or immediately following the

discovery of exceedances and would not necessarily represent 

conditions identical to those when the exceedances occurred. 

The basis for this part of the proposal is that the sitespecific CPMS operating limit reflects a 30-day average that 

should represent an actual emissions level lower than the 

three test run numerical emissions limit since variability is 

mitigated over time. Consequently, we believe that there 

should be few, if any, exceedances from the 30-day parametric 

limit and there is a reasonable basis for presuming that 

exceedances that lead to multiple performance tests to 

represent poor control device performance and to be a 
violation of the standard. Therefore, this rule proposes that 

PM CPMS exceedances leading to more than four required 

performance tests in a 12-month process operating period is 

presumed to be a violation of this standard, subject to an EGU 

owner or operator’s ability to rebut that presumption about 

process and control device operations in addition to the 

Method 5 performance test results. We solicit comment on this 

proposed revised approach.
16. Revise § 63.10023 paragraph (b) to read as follows:

§ 63.10023 How do I establish my PM CPMS operating limit and 

determine compliance with it?

* * * * *

(b) Determine your operating limit as provided in paragraph 

(b)(1) or (b)(2) of this section. You must verify an existing or 

establish a new operating limit after each repeated performance 

test.

(1) For an existing EGU, determine your operating limit based on 

the highest 1-hour average PM CPMS output value recorded during 

the performance test.

(2) For a new EGU, determine your operating limit as follows. 

(i) If your PM performance test demonstrates your PM emissions

do not exceed 75 percent of your emissions limit, you will use 

the average PM CPMS value recorded during the PM compliance 

test, the milliamp equivalent of zero output from your PM CPMS, 

and the average PM result of your compliance test to establish 

your operating limit. 

(A) Determine your instrument zero output with one of the 

following procedures.

(1) Zero point data for in-situ instruments should be obtained 

by removing the instrument from the stack and monitoring ambient 

air on a test bench.
(2) Zero point data for extractive instruments should be 

obtained by removing the extractive probe from the stack and 

drawing in clean ambient air.

(3) The zero point can also can be established obtained by 

performing manual reference method measurements when the flue 

gas is free of PM emissions or contains very low PM 

concentrations (e.g., when your process is not operating, but 

the fans are operating or your source is combusting only natural 

gas) and plotting these with the compliance data to find the 

zero intercept.

(4) If none of the steps in paragraphs (A)(1) through (3) of 

this section are possible, you must use a zero output value 

provided by the manufacturer.

(B) Determine your PM CPMS instrument average in milliamps, and 

the average of your corresponding three PM compliance test runs, 

using equation 10.

 =





∑ 





,  =





∑ 



 (Eq. 10)

Where:

X1 = the PM CPMS data points for the runs constituting the 

performance test,

Y1 = the PM emissions value (in lb/MWh) for the runs constituting 

the performance test, and

n = the number of data points. 
(C) With your instrument zero expressed in milliamps, your test

average PM CPMS milliamp value, and your test average PM 

emissions value (in lb/MWh) from your compliance runs, determine 

a relationship of PM lb/MWh per milliamp with equation 11.

X z

Y





1

1 R (Eq. 11)

Where:

R = the relative PM lb/MWh per milliamp for your PM CPMS, 

Y1 = the three run average PM lb/MWh,

X1 = the three run average milliamp output from you PM CPMS, and

z = the milliamp equivalent of your instrument zero determined 

from (i)(A).

(D) Determine your source specific 30-day rolling average 

operating limit using the PM lb/MWh per milliamp value from 

equation 11 in equation 12, below. This sets your operating 

limit at the PM CPMS output value corresponding to 75 percent of 

your emission limit.

Ol = z + (0.75(L))/ R (Eq. 12)

Where:

Ol = the operating limit for your PM CPMS on a 30-day rolling 

average, in milliamps.

L = your source PM emissions limit in lb/MWh,

z = your instrument zero in milliamps, determined from (i)(A), 

and
R = the relative lb/ton-clinker per milliamp for your PM CPMS, 

from equation 11.

(ii) If your PM compliance test demonstrates your PM emissions

exceed 75 percent of your emissions limit, you will use the 

average PM CPMS value recorded during the PM compliance test

demonstrating compliance with the PM limit to establish your 

operating limit. 

(A) Determine your operating limit by averaging the PM CPMS 

milliamp output corresponding to your three PM performance test 

runs that demonstrate compliance with the emission limit using 

equation 13.

 =





∑ 



 (Eq. 13)

Where:

X1 = the PM CPMS data points for all runs i,

n = the number of data points, and

Oh = your site specific operating limit, in milliamps. 

(iii) Your PM CPMS must provide a 4-20 milliamp output and the 

establishment of its relationship to manual reference method 

measurements must be determined in units of milliamps.

(iv) Your PM CPMS operating range must be capable of reading PM 

concentrations from zero to a level equivalent to two times your 

allowable emission limit. If your PM CPMS is an auto-ranging 

instrument capable of multiple scales, the primary range of the 

instrument must be capable of reading PM concentration from zero 
to a level equivalent to two times your allowable emission 

limit.

(v) During the initial performance test or any such subsequent 

performance test that demonstrates compliance with the PM limit, 

record and average all milliamp output values from the PM CPMS 

for the periods corresponding to the compliance test runs.

(vi) For PM performance test reports used to set a PM CPMS 

operating limit, the electronic submission of the test report 

must also include the make and model of the PM CPMS instrument, 

serial number of the instrument, analytical principle of the 

instrument (e.g. beta attenuation), span of the instruments 

primary analytical range, milliamp value equivalent to the 

instrument zero output, technique by which this zero value was 

determined, and the average milliamp signal corresponding to 

each PM compliance test run.

* * * * *