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 anindividual 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 perfo rmance 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 perfo rmance 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 exceedance s 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 exceedance s and would not necessarily represent conditions identical to those when the exceedance s occurred. The basis for this part of the proposal is that the site

specific 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, exceedance s from the 30

- day parametric limit and there is a reasonable basis for presuming that exceedance s that lead to multiple performance tests to represent poor control device performance and to be aviolation of the standard. Therefore, this rule proposes that

PM CPMS exceedance s leading to more than four required pe rformance 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 performan ce 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 emission s do not exceed 75 percent of your emission s 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 ze ro 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 l ow 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: X 1 = the PM CPMS data points for the runs constituting the performance test, Y 1 = 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 . 

#   z X Y

  1 1 

### R (Eq. 11 )

Where: R = the relative PM lb/MWh per milliamp for your PM CPMS, Y 1 = the three run average PM lb/MWh , X 1 = the three run average milliamp output from you PM CPMS, and z = the milliamp equivalent of your instrument ze ro determined from ( i )( A ). (D) Determine your source specific 30

- day rolling average operating limit using the PM lb/MWh per milliamp value from

e quation 11 in e quation 12 , below. This sets your operating limit at the PM CPMS output value corresponding to 75 percent of your emission limit. O l = z + (0.75(L))/ R (Eq. 12 ) Where: O l = the operating limit for your PM CPMS on a 30

- day rolling average, in milliamps. L = your source PM emission s limit in lb/MWh , z = your instrument zero in milliamps, determined from ( i )( A ), andR = the relative lb/ton

- clinker per milliamp for your PM CPMS,

from e quation 11 . (ii) If your PM compliance test demonstrates your PM emission s exceed 75 percent of your emission s 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

e quation 13 .

= ∑ (Eq. 13 ) Where: X 1 = the PM CPMS data points for all runs i, n = the number of data points, and Oh = your site specific operating limit, in milliamps. ( ii i) 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 capabl e of reading PM concentration from zeroto 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 mode l 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. * * * * *