December 13 , 2011

**Note :**  Subject: D ata and procedure for handling below detection level data in analyzing various pollutant emissions databases for MACT and RTR emissions limits To: SPPD management and MACT rule writers From: Peter Westlin, SPPD, MPG Ray mond Merrill, AQAD, MTG This is a note regarding the handling of below detection level (BDL) data and in developing representative detection level (RDL) data in evaluating the floor and setting emissions limits for your NSPS, MACT, and RTR rule making projects. At the end of this note is a table which includes several updates . The updates include corrected values for metals RDL, an easier to use table (e.g., sample volume versus sampling time) and some pollutants not covered in the initial table (e.g., HCl and filterable PM) . The RDL determination procedure The revised procedure for determining an RDL starts with identifying all of the available reported pollutant specific method detection levels for the best performing units regardless of any subcategory

(e.g., existing or new, fuel ty pe, etc.). From that combined pool of data, we calculate the arithmetic mean value. By limiting the data set to those tests used to establish the floor or emi ssions limit (i.e., best performers), we believe that the result is representative of the best performing testing companies and laboratories using the most sensitive analytical procedures. We believe that the outcome should minimize the effect of a test(s) with an inordinately

high method detection level ( e.g., the sample volume was too small, the laboratory technique was insufficiently sensitive, or the procedure for determining the minimum value for reporting was other than the detection level). We then call the resulting mean of the method detection levels as the representative detection level (RDL) as characteristic of accepted source emissions measurement performance. The second step in the process is to calculate three times the RDLto compare with the calculated floor or emissions limit. This step is similar to what we have used before in rulemaking applications. We use the multiplication factor of three to approximate reduce the imprecision of the analytical method until the imprecision in the field sampling reflects the relative method precision as estimated b y the ASME study 1 that also indicates that such relative imprecision, from 10 to 20 percent, remains constant over the range of the methods. For comparing to the floor, if three times the RDL were less than the calculated floor or emissions limit (e.g., calculated from the UPL), we would conclude that measurement variability was adequately addressed. The calculated floor or emissions limit would need no adjustment. If, on the other hand, the value equal to three times the RDL were greater than the UPL, we would conclude that

1 (ReMAP): PHASE 1 , Precision of Manual Stack Emission Measurements ; American Society of Mechanical Engineers , Research Committee on Industrial and Municipal Waste , February 200 1.the calculated floor or emissions limit does not account entirely for measurement variability. If

indicated, we substituted the value equal to three times the RDLfor the c alculated floor or emissions limit which results in a concentration where the method would produce measurement accuracy on the order of 10 to 20 percent similar to other EPA test methods and the results found in the ASME study. We determined the RDL for each pollutant using data from tests of all the best performers for all of the final regulatory

subcategories (i.e., pooled test data). We applied the same pollutantspecific RDL and emissions limit adjustment procedure to all subcategories for which we established emissions limits. We believe that emissions limits adjusted in this manner better ensure measurement variability is adequately

addressed relative to compliance determinations than did the procedure applied for the proposal that may have been based on data sets smaller than seven tests and as few as one test. We also believe that the emissions testing procedures and technologies available now and in the future will be adequate to provide the measurement certainty sufficient for sources to demonstrate compliance at the levels of the adjusted emissions limits when applied in the manner representative of this protocol . **We recommend that rule writers considering emissions limits for these pollutants**  **review the exis** **ting data sets and compare the R DL values used in earlier analyses with the revised**  **RDLs shown in the attached table. We believe that these revised values and the procedures described in the table**  **better reflect representative method capabilities and should be used**  **in data**  **review for**  **cu rrent rule development projects**  **and in setting representative emissions limits.**  Results of MDL/RDL data analys es We have collected data used for the boilers rule reconsideration and the proposed utility MACT in light of the comments to review the effect of available larger pools of dioxin/furan emissions as measured with Method 23 and the Hg emissions as measured with Method 29 of data for these sources. The expanded data set represents several hundred emissions tests used in the floor calculations (i.e., best performers) for the boilers and utility rules. We presume that data for the best performing units also refl ect the capabilities of high quality testing companies and laboratories. Further, the method detection levels calculated from larger data are more representative of the inherent measurement variability both within and between testing companies. We have also included data on the RDLvalues for the individual metals as measured with Method 29 based on a similar assessment of data collected during method development. The table s attached below express the results in two formats: 1) The mass of pollutant sample the method can detect quantitatively and is representative of the method detection level (RDL) for the set of data collected for the specific rule development; and 2) The lowest concentrations that could be measured quantitatively for a range of sampl e volumes for use in comparing to calculated UPL values and in setting applicable emissions limits.The first table represents a thorough review of D/F emissions data for both the boilers and utility

data sets. Not too surprisingly, the resulting values are similar but not identical. Our first observation is that these calculated representative detection levels are generally greater in magnitude than those calculated for the initial reviews and particularly for establishing new source limits (i.e., for the single best performing unit). The second observation is that the RDLs determined for the utility ICR data set are lower in magnitude than for the boiler data collected during an earlier ICR project. We believe that the boiler data set includes some data reported incorrectly

(e.g., laboratory

reporting limits rather than method detection limits) and that the utility D/F data set includes fewer of these misreported data. As a result, we believe that the RDLs determined from the utility D/F data set are more representative of current expected measurement data quality. The application procedures described in the table reflect this conclusion. Also attached to this note is a spreadsheet example of the calculations used to develop these values. As rule writers collect additional data in the future and test methods and techniques improve, there will be a need to assess new data for representative method detection capabilities. We will prepare new procedures for you and your contractors to use as needed in future rule making activities based on these findings. We will build on these procedures to reflect greater reliance on the broadest set of measurement data available and provide default values to use when there are only a few (e.g., fewer than seven) p erformance test results available for a source category. Peter Westlin Measurement Policy

Group Sectors Policies and Programs Division Ray mond Merrill Measurement Technology Group Air Quality

Assessment Division Addressees: SPPD management SPPD technical staff cc : Conniesue Oldham, MTG, AQAD Jason Dewees, MTG, AQAD Kim Garnett, MTG, AQAD Kristen Benedict, MTG, AQAD Robin Segall, MTG, AQAD**Summary of pollutant**  **emissions representative**  **method detection level analyses and a regulatory**  **emissions limit setting**  **procedure RDL**  **(ng) 3 x**  **RDL (ng**  **) 3 x RDL Concentrations**  **(ng/dscm) 1 dscm test**  **2 dscm test 3 dscm test**  **4 dscm test 6 dscm test**  **8 dscm test** Ind. Boilers D/F total mass (Method 23) 5.6E - 01 **1.7E+00** 1.7E+00 8.5E - 01 5.7E - 01 4.3E - 01 2.8E - 01 2.1E - 01 Ind. Boilers TEQ (Method 23) 8.2E - 02 **2.5E -** **01** 2.5E - 01 1.3E - 01 8.3E - 02 6.3E - 02 4.2E - 02 3.1E - 02 Utilities D/F total mass (Method 23) 3.1E - 01 **9.2E -** **01** 9.2E - 01 4.6E - 01 3.1E - 01 2.3E - 01 1.5E - 01 1.2E - 01 Utilities TEQ (Method 23) 3.6E - 02 **1.1E -** **01** 1.1E - 01 5.5E - 02 3.7E - 02 2.8E - 02 1.8E - 02 1.4E - 02 **RDL (ug) 3 x RDL** 

**(ug) 3 x RDL Concentrations**  **(ug/dscm)**

**1 dscm test 2 dscm test**  **3 dscm test 4 dscm test**  HCl/Cl2 (Method 26A) 6.0E+1 **1.8E+2** 1.8E+02 9.0E+0 1 6.0E+0 1 4.5E+0 1 PM filterable (Method 5) 1.0E+3 **3.0E+3** 3.0E+0 3 1.5E+0 3 1.0E+0 3 7.5E+02 Ind. Boiler Hg (Method 29) 8.3E - 01 **2.5E+00** 2.1 E+00 1.0E+00 7.1 E - 01 6.2E - 01 **120L test 240L test**  **360L test** HCl/CL2 (Method 26) 1.0E+01 **3.0E+01** 2.5E+02 1.3E+02 8.3E+01**Summary of pollutant emissions representative method detection level analyses and regulatory emissions limit setting** 

**procedure for Method 29 Metals using**  **Inductively Coupled Atomic Emission**  **Spectroscopy or Atomic Absorption Analysis** 

**Method 29 Metal RDL** 

**ICP/AES or AA**  **(ug) 3 X RDL**  **ICP/AES or AA**  **(ug) 3 x RDL**  **Concentrations (**   **g/dscm) 1 dscm test**  **2 dscm test 3 dscm test**  **4 dscm test** Antimony 1.2E+01 3.5E+01 3.5E+01 1.7E+01 1.2E+01 8.6E+00 Arsenic 1.9E+01 5.7E+01 5.7E+01 2.9E+01 1.9E+01 1.4E+01 Barium 8.0E - 01 2.4E+00 2.4E+00 1.2E+00 8.0E - 01 6.0E - 01 Beryllium 1.1E - 01 3.3E - 01 3.3E - 01 1.7E - 01 1.1E - 01 8.3E - 02 Cadmium 1.5E+00 4.5E+00 4.5E+00 2.3E+00 1.5E+00 1.1E+00 Chromium 2.5E+00 7.5E+00 7.5E+00 3.8E+00 2.5E+00 1.9E+00 Cobalt 2.5E+00 7.5E+00 7.5E+00 3.8E+00 2.5E+00 1.9E+00 Copper 2.1E+00 6.3E+00 6.3E+00 3.2E+00 2.1E+00 1.6E+00 Lead 1.5E+01 4.5E+01 4.5E+01 2.3E+01 1.5E+01 1.1E+01 Manganese 7.0E - 01 2.1E+00 2.1E+00 1.1E+00 7.0E - 01 5.3E - 01 Mercury* 5.6E - 01 1.7E+00 1.7E+00 8.4E - 01 5.6E - 01 4.2E - 01 Nickel 5.4E+00 1.6E+01 1.6E+01 8.1E+00 5.4E+00 4.1E+00 Phosphorus 2.7E+01 8.1E+01 8.1E+01 4.1E+01 2.7E+01 2.0E+01 Selenium 2.7E+01 8.1E+01 8.1E+01 4.1E+01 2.7E+01 2.0E+01 Silver 2.6E+00 7.8E+00 7.8E+00 3.9E+00 2.6E+00 2.0E+00 Thallium 1.4E+01 4.3E+01 4.3E+01 2.2E+01 1.4E+01 1.1E+01 Zinc 8.0E - 01 2.4E+00 2.4E+00 1.2E+00 8.0E - 01 6.0E - 01 *Mercury analyz ed b y Cold Vapor AA RDL= Method derived regulatory detection limit based. ICP/AES = Inductively Coupled Argon Plasma/Atomic Emission Spectroscopy AA = Atomic Absorption Spectroscopy GFAA = Graphite Furnace Atomic Absorption spectroscopy**Summary of pollutant emissions representative method detection level analyses and regulatory emissions limit setting**

**procedure for Method 29 Metals using**  **Inductively Coupled Pl asma/Mass Spectrometry**  **or Graphite Furnace**  **Atomic Absorption Analysis** 

**Method 29 Metal**  **RDL**

**ICP/MS or GFAA**  **(**  **g /dscm**  **) 3 X RDL**  **ICP/MS or GFAA**  **(**  **g /dscm**  **) Concentrations**  **(**  **g/dscm) 1 dscm**  **test 2 dscm**  **test 3 dscm test**  **4 dscm test 5 dscm**  **test** Antimony 1.1E+00 3.3E+00 3.3E+00 1.7E+00 1.1E+00 8.3E - 01 6.6E - 01 Arsenic 4.0E - 01 1.2E+00 1.2E+00 6.0E - 01 4.0E - 01 3.0E - 01 2.4E - 01 Barium ** 8.0E - 01 2.4E+00 2.4E+00 1.2E+00 8.0E - 01 6.0E - 01 4.8E - 01 Beryllium 8.0E - 02 2.4E - 01 2.4E - 01 1.2E - 01 8.0E - 02 6.0E - 02 4.8E - 02 Cadmium 3.0E - 02 9.0E - 02 9.0E - 02 4.5E - 02 3.0E - 02 2.3E - 02 1.8E - 02 Chromium 3.0E - 01 9.0E - 01 9.0E - 01 4.5E - 01 3.0E - 01 2.3E - 01 1.8E - 01 Cobalt 3.0E - 01 9.0E - 01 9.0E - 01 4.5E - 01 3.0E - 01 2.3E - 01 1.8E - 01 Copper ** 2.1E+00 6.3E+00 6.3E+00 3.2E+00 2.1E+00 1.6E+00 1.3E+00 Lead 3.0E - 01 9.0E - 01 9.0E - 01 4.5E - 01 3.0E - 01 2.3E - 01 1.8E - 01 Manganese 3.0E - 01 9.0E - 01 9.0E - 01 4.5E - 01 3.0E - 01 2.3E - 01 1.8E - 01 Mercury* 5.6E - 01 1.7E+00 1.7E+00 8.4E - 01 5.6E - 01 4.2E - 01 3.4E - 01 Nickel ** 5.4E+00 1.6E+01 1.6E+01 8.1E+00 5.4E+00 4.1E+00 3.2E+00 Phosphorus ** 2.7E+01 8.1E+01 8.1E+01 4.1E+01 2.7E+01 2.0E+01 1.6E+01 Selenium 8.0E - 01 2.4E+00 2.4E+00 1.2E+00 8.0E - 01 6.0E - 01 4.8E - 01 Silver ** 2.6E+00 7.8E+00 7.8E+00 3.9E+00 2.6E+00 2.0E+00 1.6E+00 Thallium 3.0E - 01 9.0E - 01 9.0E - 01 4.5E - 01 3.0E - 01 2.3E - 01 1.8E - 01 Zinc 8.0E - 01 2.4E+00 2.4E+00 1.2E+00 8.0E - 01 6.0E - 01 4.8E - 01 *Mercury analyz ed b y Cold Vapor AA ** Common metals analyzed by Inductively Coupled Plasma/AES or Flame Atomic Absorption Spectroscopy RDL= Method derived regulatory detection limit based on 1.25 dscm collected in 1 hour. ICP/MS = Inductively C oupled Argon Plasma/Mass SpectrometryGFAA = Graphite Furnace Atomic Absorption spectroscopy

Except for assessing boiler and CISWIdata, we recommend that you select D/F data calculated from the utilities ’ data set rather than for the industrial boilers in conducting the following analys es. 1. Calculate the UPL for your respective data set in units o f pollutant mass as sampled by the test method (e. g. , total ng of D/F, total TEQ of D/F, ug of Hg) . 2. Compare the 3xRDL mass value (shown in **bold**) to the calculated UPL . If 3xRDL mass < UPL mass , use the UPLvalue for rulemaking. If 3xRDL> UPL, use the 3xRDLvalue for rulemaking. For source categories other than boilers, use the 3xRDL D/F values shown above for Utilities. 3. Alternatively, you may calculate the UPL for your data set in units of pollutant concentration (ng/dscm for D/F, ug/dscm for Hg). If so, repeat steps 1 and 2 selecting the concentration associated with the sample volume appropriate for your ICR or regulatory

decision. You may

also determine to convert the values in the table to other emissions formats (e.g., lb/MMBtu or lb/MWh) for these comparisons.Example spreadsheet: (ng/dscm @ 7 percent O2) ng ng mass (average of all congener data in set) TEQ (average of

all TEQ per congener in set) lab mass TEQ Total OCDD 2.19E - 02 6.24E - 06 8.77E - 02 2.50E - 05 Total OCDF 6.72E - 03 1.89E - 06 2.69E - 02 7.55E - 06 1,2,3,4,6,7,8 HpCDD 2.95E - 03 2.70E - 05 1.18E - 02 1.08E - 04 1,2,3,4,6,7,8 HpCDF 6.10E - 03 6.02E - 05 2.44E - 02 2.41E - 04 1,2,3,4,7,8 HxCDD 1.16E - 03 1.06E - 04 4.63E - 03 4.25E - 04 1,2,3,4,7,8 HxCDF 8.24E - 03 8.10E - 04 3.30E - 02 3.24E - 03 1,2,3,4,7,8,9 HpCDF 3.08E - 03 3.00E - 05 1.23E - 02 1.20E - 04 1,2,3,6,7,8 HxCDD 1.33E - 03 1.23E - 04 5.32E - 03 4.93E - 04 1,2,3,6,7,8 HxCDF 9.64E - 04 8.83E - 05 3.86E - 03 3.53E - 04 1,2,3,7,8 PeCDD 4.40E - 03 4.33E - 03 1.76E - 02 1.73E - 02 1,2,3,7,8 PeCDF 1.82E - 03 5.26E - 05 7.29E - 03 2.10E - 04 1,2,3,7,8,9 HxCDD 3.37E - 03 3.26E - 04 1.35E - 02 1.30E - 03 1,2,3,7,8,9 HxCDF 7.81E - 04 6.93E - 05 3.12E - 03 2.77E - 04 2,3,4,6,7,8 HxCDF 2.35E - 03 2.27E - 04 9.40E - 03 9.09E - 04 2,3,4,7,8 PeCDF 1.61E - 03 4.61E - 04 6.43E - 03 1.85E - 03 2,3,7,8 -TCDD 3.38E - 03 3.34E - 03 1.35E - 02 1.34E - 02 2,3,7,8 -TCDF 2.24E - 03 2.18E - 04 8.98E - 03 8.73E - 04

max DL 2.19E - 02 4.33E - 03 8.77E - 02 1.73E - 02 min DL 7.81E - 04 1.89E - 06 3.12E - 03 7.55E - 06 mean DL 4.26E - 03 6.05E - 04 1.70E - 02 2.42E - 03

sum 7.24E - 02 1.03E - 02 2.90E - 01 4.11E - 02 RDL = EDL x 2 1.45E - 01 2.06E - 02 5.80E - 01 8.22E - 02 RDL x 3 > floor? 4.35E - 01 6.17E - 02 1.74E+00 2.47E - 01