Date: November 6, 2014

To: Jeff Telander, EPA/OAQPS/SPPD

From: Gabrielle Raymond and Kristin Sroka (RTI International)

Subject: Maximum Achievable Control Technology (MACT) Floor Analysis for Brick and 

Structural Clay Products

I. Introduction

In accordance with section 112 of the Clean Air Act (CAA), the U.S. Environmental 

Protection Agency (EPA) established national emission standards for hazardous air pollutants 

(NESHAP) on May 16, 2003, for the brick and structural clay products (BSCP) manufacturing 

industry. The NESHAP regulated emissions of hydrogen fluoride (HF), hydrogen chloride 

(HCl), and particulate matter (PM)—a surrogate for hazardous air pollutant (HAP) metals—from 

tunnel kilns located at BSCP facilities. On March 13, 2007, the D.C. Circuit Court vacated the 

emission standards for BSCP manufacturing due to issues associated with the methodology used 

to determine the minimum regulatory “floors” for new and existing units.

1

 Therefore, the EPA is 

proposing new standards for BSCP manufacturing, including standards for HF, HCl, chlorine 

(Cl2), mercury (Hg), and non-Hg HAP metals (or PM surrogate).

Section 112 of the CAA requires that the EPA establish NESHAP for the control of the 

HAP emitted from both new and existing sources in a source category. These standards must 

reflect the maximum degree of reduction in the HAP emissions that is achievable. The minimum 

level of control is referred to as the “maximum achievable control technology (MACT) floor.” 

The method for determining the MACT floor is defined for both new and existing sources by 

CAA section 112(d)(3). For new sources, the MACT floor cannot be less stringent than the 

emission control that is achieved in practice by the best controlled similar source. For existing 

sources, the MACT floor cannot be less stringent than the average emission limitation achieved 

by the best performing 12 percent of existing sources for source categories with 30 or more 

sources, or the best performing 5 sources for source categories with fewer than 30 sources.

The purpose of this memorandum is to present the methodology and the results of the

MACT floor analysis for the BSCP source category. This MACT floor analysis uses data 

collected in a survey of BSCP owners and operators conducted by the EPA in 2008 and 2010

under section 114 of the CAA. The emissions data supplied by BSCP owners and operators in 

 1 Sierra Club v. EPA, 479 F.3d 875 (D.C. Cir. 2007).
2

response to the survey were compiled into a Microsoft Excel® data base that serves as the 

dataset used for this MACT floor analysis (referred to in this memorandum as the “survey

dataset”). For more details about the survey dataset, see Test Data Used in BSCP Proposed Rule

(Raymond, 2014).

II. Hazardous Air Pollutants

The specific chemicals, compounds, or groups of compounds designated to be HAP are 

listed in CAA section 112(b). Included on the list are metals, organic compounds, and inorganic 

chemicals. From this HAP list, the following HAP were identified to be emitted from BSCP 

facilities: the acid gases HF, HCl, and Cl2; the metals antimony (Sb), arsenic (As), beryllium 

(Be), cadmium (Cd), chromium (Cr), cobalt (Co), lead (Pb), manganese (Mn), Hg, nickel (Ni), 

and selenium (Se); and dioxins and furans (D/F). MACT floor levels for HAP metals other than 

Hg were analyzed using filterable PM emissions as a surrogate for total non-Hg HAP metals 

from BSCP facilities (see the preamble to the BSCP proposed rule for more information about 

filterable PM as a surrogate for total non-Hg HAP metals).

MACT floors were not developed for acid gases or D/F. A health-based emission limit 

was developed for acid gases under CAA section 112(d)(4), and work practice standards were 

developed for D/F under CAA section 112(h). The rationale behind these standards is discussed 

in the preamble to the BSCP proposed rule.

III. MACT Floor Analysis Subcategories

Under CAA section 112(d)(1), the EPA has the discretion to “...distinguish among 

classes, types, and sizes of sources within a category or subcategory in establishing...” standards. 

When separate subcategories are established, a MACT floor is determined separately for each 

subcategory. To determine whether the BSCP source category warrants subcategorization for 

the MACT floor analysis, the EPA reviewed BSCP tunnel kiln design, operating information, 

and emissions data compiled in the survey dataset and other information collected by the Agency 

for development of the NESHAP for this source category (Raymond et. al, 2014). Based on this 

review, the EPA concluded that there are significant design and operational differences in BSCP 

tunnel kilns that affect the levels of emissions of certain HAP to justify subcategorizing BSCP 

tunnel kilns for the purpose of establishing MACT floors. For the BSCP source category, the 

following two subcategories were identified:

• Large tunnel kilns: New and existing BSCP tunnel kilns with a design capacity equal to 

or greater than 10 tons per hour (tph) of fired product.

• Small tunnel kilns: New and existing BSCP tunnel kilns with a design capacity less than 

10 tph of fired product.

For the proposed standards, these subcategories were only used for the MACT floors for 

Hg. In the subcategory analysis (Raymond et. al, 2014), the data showed that for PM, sources 

controlled with a fabric filter-based control device (i.e., a dry injection fabric filter (DIFF), dry 

lime scrubber and fabric filter (DLS/FF), or a stand-alone fabric filter (FF)) are better performers 

as a group than kilns without fabric filter-based controls. Therefore, the proposed MACT floor 
3

for PM (as a surrogate for non-Hg HAP metals) was developed without size subcategories and 

was based on emissions data for the sources with fabric filter-based controls.

As discussed in Section VI of this memorandum, the EPA is also considering the 

alternate approach of subcategorizing the PM data by kiln size. Therefore, this memorandum 

also presents the MACT floors for that alternate approach.

IV. MACT Floor Analysis Concepts

A. Upper Prediction Limit

The MACT floor analysis for BSCP manufacturing uses an upper prediction limit (UPL) 

approach to identify the average emission limitation achieved by those best performing sources. 

The EPA uses a UPL approach in its MACT floor analyses because it incorporates the average 

performance of the best performing sources and the variability of the performance during testing 

conditions. The UPL represents the value which one can expect the mean of a specified number 

of future observations (e.g., 3-run average) to fall below for the specified level of confidence, 

based upon the results of an independent sample from the same population. The level of 

confidence represents the level of protection afforded to facilities whose emissions are in line 

with the best performers. For example, a 99 percent level of confidence means that a facility 

whose emissions are in line with the best performers has one chance in 100 of exceeding the 

floor limit. A prediction interval for a single future observation (or an average of several test 

observations) is an interval that will, with a specified degree of confidence, contain the next (or 

the average of some other pre-specified number of) randomly selected observation(s) from a 

population. In other words, the UPL estimates what the upper bound of future values will be, 

based upon present or past background samples taken. The UPL approach encompasses all the 

data point-to-data point variability. The predictions derive from the dataset to which it is 

applied, and, thus, can be applied to any type of data.

There are different equations for calculating a UPL based on the distribution of the 

dataset. Data can be normally distributed, lognormally distributed, or neither and thus have a 

skewed/unknown distribution. The EPA implemented the statistical tests of skewness and 

kurtosis to determine the distribution of the best performing sources’ data.

The skewness statistic (S) characterizes the degree of asymmetry of a given data 

distribution. Normally distributed data have an S value of zero. An S value that is greater than 

zero indicates that the data are asymmetrically distributed with a right tail extending towards 

positive values; similarly, an S value that is less than zero indicates that the data are 

asymmetrically distributed with a left tail extending towards negative values. The value of S can 

be approximated using the following equation (which is implemented in Microsoft Excel® using 

the “SKEW” function):
4

( )( )

3

1 2 1

∑=





 



 −

− − =

n

i

i

stdev

x x

n n

n Skewness

where:

n = sample size

x = mean of MACT floor pool

xi = individual source mean

stdev = ( )

( ) ∑ −

−

1

2

n

x x i

As part of determining whether a data distribution can be considered normal, the S value 

must be compared to the standard error of the skewness statistic (SES). The SES value can be 

approximated using the following equation:

( )( )

( 2)( 1)( 3)

6 1

− + +

× − = n n n

n n SES

According to the skewness hypothesis test, if the absolute value of S is less than two times the 

absolute value of SES, the skewness of the data can be considered normal.

The kurtosis statistic (K) characterizes the degree of peakedness or flatness of a given 

data distribution in comparison to a normal distribution. Normally distributed data have a K 

value of zero. A K value that is greater than zero indicates a relatively peaked distribution. A K 

value that is less than zero indicates a relatively flat distribution. The estimate of K can be 

calculated one of two ways. For datasets with more than three run values, kurtosis can be 

estimated using the following equation (which is implemented in Microsoft Excel® using the 

“KURT” function):

( )

( )( )( )

( )

( 2)( 3)

3 1

1 2 3

1 4 2

− −

− −















 



 



 −

− − −

+ = ∑ n nn

stdev

x x

n n n

n n Kurtosis

This equation cannot be used for datasets with three run values (n=3) because there will 

be a zero in the denominator of the first and second term. Instead, for datasets with three run 

values, kurtosis is estimated using the following equation:

( )

( )( ) 3

1 4

1

4

− −

+

=

∑=

n stdev

x x

Kurtosis

n

i

i
5

As part of determining whether a data distribution can be considered normal, the K value 

must be compared to the standard error of the kurtosis statistic (SEK). The SEK value can be 

approximated using the following equation:

( ( ))

( 2)( 3)( 3)( 5)

24 1 2

− + − +

− = n n n nn n SEK

(for datasets with more than three runs (n>3))

n

SEK 24 =

(for datasets with three runs (n=3))

According to the kurtosis hypothesis test, if the absolute value of K is less than two times 

the absolute value of SEK, the kurtosis of the data can be considered normal.

For this MACT floor analysis, if the results from both the skewness and kurtosis 

hypothesis tests indicated the dataset was normally distributed, the dataset was treated as

normally distributed in subsequent UPL calculations. If either of these tests indicated the dataset

was not normally distributed, the dataset was log-transformed, and the log-transformed dataset

was evaluated for kurtosis and skewness. If both tests of the log-transformed data indicated the 

log-transformed dataset was normally distributed, the dataset was treated as lognormally 

distributed in subsequent UPL calculations. If either of these tests indicated the log-transformed 

dataset was not normally distributed, the dataset was treated as skewed/unknown distribution in 

subsequent UPL calculations.

For datasets with only three run values, the result of both the skewness and kurtosis 

hypothesis tests always indicate the dataset is normally distributed. Therefore, to determine the 

appropriate data distribution for those datasets, the skewness/SES values from raw data were 

compared to the skewness/SES values from log-transformed data. The smaller skewness/SES 

value was selected as an indication of a larger likelihood of the data to come from the 

corresponding distribution.

After completing the determination of the type of data distribution for each dataset, the 

UPL was calculated using the corresponding equation for the distribution for that dataset. The 

UPL equations for normal, lognormal, and skewed/unknown distribution datasets are provided 

below.

Normally Distributed Dataset





 



 = + +

n m

UPL x t s df

2 1 1 ,0.99

where:

UPL = upper prediction limit
6

x = mean of the data calculated as ∑= ∑ = = N

i

n

j ij

i

x

n

x

1 1

1

n = number of test runs = ∑=

N

i i n

1

m = number of future test runs in the compliance average

N = number of sources

s

2 = pooled variance calculated as ∑ ( ) = = − n

i i x x

n

s

1

2 1 2

tdf,0.99 = quantile of t-distribution at the 99 percent level of confidence with degrees of 

freedom (df); this value can be calculated with the Student’s t-test statistical 

method, using the “TINV” function in Microsoft Excel® software

df = degrees of freedom calculated as ( ) 1

1 = ∑ − =

N

i i df n

Lognormally Distributed Dataset (Bhaumik and Gibbons, 2004)

( ) ( )















− = + − + + + + +2 1

ˆ ˆ 1

2 4

99 2 ˆ ˆ ˆ 2 2 ˆ ˆ 2 0.

ˆ ˆ 2 2 2

2

n n

me e m e

m

z UPL e m σ σ m σ σ σ σ m

where:

μˆ = 

n

log y n

i ∑ i =1 ( )

= the average of the log transformed data from the data

2 σˆ = ( ( ) )

1

ˆ 1

2

−

∑ − =

n

log y n

i i μ

= variance estimate of the log transformed data

z0.99 = the 99th-percentile of the log-normal distribution estimated using the 

trapezoidal rule approach from the following equation:

( ) ( )( ) ( ) 0.99

24

3 3 6 3

6

1 0.99

0

2 4

1 3 2 = 













 − − + − − + ∫ z

z z

z z z z z φ β β

Skewed/Unknown Distribution (Non-Normal/Non-Lognormal) (Gayen, 1949)





 



 = + +

n m

UPL x t s df p

2 1 1 ,

where:

UPL = upper prediction limit
7

x = mean of the data calculated as ∑= ∑ = = N

i

n

j ij

i

x

n

x

1 1

1

n = number of test runs = ∑=

N

i i n

1

m = number of future test runs in the compliance average

N = number of sources

s

2 = pooled variance calculated as ∑ ( ) = = − n

i i x x

n

s

1

2 1 2

tdf,p = recalculated quantile of t-distribution based on specified level of confidence 

(i.e., 99%)

df = degrees of freedom calculated as ( ) 1

1 = ∑ − =

N

i i df n

B. Representative Detection Limit

The imprecision of test method measurements is another component of data variability. 

At very low emissions levels, as encountered in some of the data in the BSCP dataset, the 

inherent imprecision in the pollutant measurement method has a large influence on the reliability 

of the data underlying a MACT floor emission limit. Of particular concern are those data that 

are reported near or below a test method’s pollutant detection capability. Because of matrix 

effects, laboratory techniques, sample volume, and other factors, method detection limits

normally vary from test to test. The guidelines for the 2010 section 114 BSCP survey requested 

that sources identify (i.e., flag) data which were measured below the method detection limit and 

to report those values as equal to the test-specific method detection limit.

Variability of data due to measurement imprecision is inherently and reasonably 

addressed in calculating a MACT floor emission limit when most of the data are significantly 

above the method detection limit. For datasets with a large number of test results below the 

method detection limit (reported as method detection limit values), other techniques need to be 

used to account for data variability. Indeed, under such a shift, the data distribution becomes 

truncated on the lower end, leading to an artificial overabundance of values occurring at the 

method detection limit. There is a concern that a MACT floor emission limit based on a 

truncated data base (i.e., calculated using values at or near the method detection limit) may not 

account adequately for data measurement variability, because the measurement error associated 

with those values provides a large degree of uncertainty.

The expected measurement imprecision for an emissions value occurring at or near the 

detection limit is about 40 to 50 percent. Relative pollutant measurement imprecision decreases 

to a consistent 10 to 15 percent for values measured at a level about three times the method 

detection limit (ASME, 2001).

The approach taken to account for measurement variability includes defining a detection 

limit that is representative of the data used in establishing a MACT floor emission limitation and 

also minimizes the influence of an outlier test-specific method detection limit value. The EPA 
8

has developed a list of representative detection levels (RDL) from available pollutant-specific 

method detection levels (Westlin and Merrill, 2011). These RDL values are then multiplied by 

three to decrease measurement imprecision to around 10 to 15 percent (as noted in the previous 

paragraph), resulting in values referred to as “3xRDL” values.

The appropriate 3xRDL value is compared to the calculated UPL value for each pollutant 

and subcategory. The larger of the 3xRDL value and the calculated UPL value is used for the 

MACT floor emission limit to ensure that measurement variability is adequately addressed. This 

check was part of the variability analysis for all existing MACT floors that had below detection 

level (BDL) or detection level limited (DLL) run data present in the best performing datasets.

For more information regarding the general use of the UPL and why it is appropriate for 

calculating MACT floors, see the memorandum Use of the Upper Prediction Limit for 

Calculating MACT Floors (Telander, 2014a).

V. MACT Floor Analysis Methodology

A. MACT Floor Calculation Steps

Step 1.

The first step in the MACT floor analysis was to calculate an average emission value for 

each source per pollutant based on the available test data.

For any run fractions per test run marked as “< method detection limit (or other reporting 

limit)” the fraction was considered BDL.

2 For this analysis, the method detection limit for that 

fraction was used as the mass to calculate a run value (i.e., lb/ton, μg/dscm, and lb/hr). For PM 

runs, if the mass was below the 1 milligram (mg) RDL value, 1 mg was used as the mass to 

calculate a run value (Raymond, 2014). Step 6 was added to the MACT Floor Calculation Steps 

to account for datasets with BDL values.

Step 2.

Once an average emission value was calculated for each source, in each subcategory and 

pollutant, all of the individual average emission values were ranked from lowest to highest value. 

See Appendix A for the rankings for each pollutant and subcategory.

Step 3.

From the rankings shown in Appendix A, the best performing sources were identified

consistent with the criteria in CAA section 112(d)(3) for determining MACT floors for new and 

existing sources. These sources are referred to as the “MACT floor pool.” For the new source 

MACT floors, the best controlled similar source was identified from the sources that had

individual source test run data in the survey dataset. For the existing source MACT floors, the 

 2 For the EPA Method 29 multi-metals test, each metal lab analysis typically has two separate fractions: front-half 

(filter) and back-half (impinger catch); mercury can have three additional back-half fractions.
9

number of sources in the MACT floor pool was determined on an individual subcategory basis,

as described in Table 1.

Table 1. Number of Sources in Existing Source MACT Floor Pool

Pollutant Subcategory

No. 

Sources 

Nationwide

No. 

Sources 

with Data

No. Sources 

in MACT 

Floor Pool Based on

PM None; used data from kilns 

with fabric filter-based controls 225 31 27 12% of sources nationwide

Hg Large Kilns 122 19 3 12% of sources 

with data

Hg Small Kilns 103 2 1 12% of sources 

with data

Step 4.

Each MACT floor dataset (for each subcategory and pollutant) was evaluated for kurtosis 

and skewness to determine the distribution, as described in Section IV.A of this memorandum.

Step 5.

After determining the type of data distribution for the dataset, the UPL was calculated 

using the corresponding equation for the distribution for that dataset, as described in Section 

IV.A of this memorandum. See Appendix B for UPL summary tables for new and existing 

sources.

Step 6.

For source datasets that contained BDL or DLL data, there was an additional step taken 

after the subcategory UPL was calculated. The results of the UPL calculation were compared to 

the 3xRDL value of the relevant performance test method(s) (Westlin and Merrill, 2011). As 

described in Section IV, this step ensures that data measurement variability is addressed.

The 3xRDL values in the guidance document (Westlin and Merrill, 2011) were given in 

units of concentration (micrograms per dry standard cubic meter [μg/dscm] with no oxygen 

correction). The PM emission limits for the proposed BSCP NESHAP are in units of pound per 

ton (lb/ton) of brick and grains per dry standard cubic foot at 7 percent oxygen (gr/dscf @ 7% 

O2). The proposed Hg emission limits are in units of lb/ton of brick, micrograms per dry 

standard cubic meter at 7 percent oxygen (μg/dscm @ 7% O2), and pounds per hour (lb/hr). In 

order to compare the calculated UPL to the 3xRDL, the 3xRDL value was converted to the units 

of the emission limits using a ratio of the emission data in the units of interest (e.g., lb/ton brick) 

to the emission data in μg/dscm (uncorrected). See Appendix C for more details about the 

conversion of the 3xRDL values to the units of measure used in UPL calculations.
10

The converted 3xRDL value was then compared to the calculated UPL in the same units 

of measure. If the calculated UPL value was less than the 3xRDL value, the 3xRDL value was 

used as the basis for the standard because the 3xRDL value provides the lowest emission rate 

that can be measured using the performance test method while maintaining a relative method 

precision on the order of 10 to 20 percent of the measured value. If the UPL value was equal to 

or greater than the 3xRDL value, then the UPL value was used as the basis for the standard.

Step 7.

For limited datasets with less than seven data points, the steps outlined in the 

memorandum Approach for Applying the Upper Prediction Limit to Limited Datasets (Telander, 

2014b) were followed. See Appendix D for more details about limited datasets.

B. Calculation of Equivalent Limits

As previously noted, in addition to the lb/ton emission limits for PM and Hg, equivalent 

limits in other units of measure were developed for those pollutants. The MACT floors were 

calculated in units of lb/ton first. For the equivalent concentration-based limits for PM and Hg 

and the equivalent lb/hr limit for Hg, the concentration or lb/hr data were used from the best 

performing sources as determined from the lb/ton UPL ranking.

The survey dataset did not include much total non-Hg HAP metals data, particularly for 

the kilns in the MACT floor pool for PM. Therefore, the total non-Hg HAP metals equivalent 

lb/hr limit was calculated from the PM MACT floor lb/ton limit using an average production rate 

(tph) and the average total non-Hg HAP metals content of the PM (as a percentage of PM) for 

sources in the MACT floor pool. See Appendix E for more details about the development of the 

conversion factors and calculation.

VI. MACT Floor Analysis Results

Tables 2 and 3 present the existing source and new source MACT floor values 

determined for the BSCP source category. In addition to these MACT floors, the equivalent total 

non-Hg HAP metals limits were calculated as described in Appendix E to be 0.022 lb/hr for 

existing sources and 0.0018 lb/hr for new sources.
11

Table 2. Proposed Existing Source MACT Floors

Subcategory Pollutant Avg. 99% UPL 3xRDL

MACT 

Floor Unit of Measure

All Kilns PM 0.041 0.16 0.022 0.16 lb/ton

Equivalent PM 0.011 0.040 0.0066 0.040 gr/dscf @ 7% O2

Large Kilns Mercury 1.6E-05 2.2E-05 8.0E-06 2.2E-05 lb/ton

Equivalent Mercury 14 29 6.4 29 μg/dscm @ 7% O2

Equivalent Mercury 1.7E-04 2.7E-04 8.0E-05 2.7E-04 lb/hr

Small Kilns Mercury 1.8E-04 2.0E-04 1.7E-05 2.0E-04 lb/ton

Equivalent Mercury 62 70 6.1 70 μg/dscm @ 7% O2

Equivalent Mercury 0.0010 0.0011 2.4E-04 0.0011 lb/hr

Table 3. Proposed New Source MACT Floors

Subcategory Pollutant Avg. 99% UPL 3xRDL

MACT 

Floor Unit of Measure

All Kilns PM 0.0060 0.018 0.022 0.022 lb/ton

Equivalent PM 0.0020 0.0059 0.0066 0.0066 gr/dscf @ 7% O2

Large Kilns Mercury 1.5E-05 2.0E-05 8.0E-06 2.0E-05 lb/ton

Equivalent Mercury 10 13 6.4 13 μg/dscm @ 7% O2

Equivalent Mercury 0.00018 0.00024 8.0E-05 0.00024 lb/hr

Small Kilns Mercury 1.8E-04 2.0E-04 1.7E-05 2.0E-04 lb/ton

Equivalent Mercury 62 70 6.1 70 μg/dscm @ 7% O2

Equivalent Mercury 0.0010 0.0011 0.00020 0.0011 lb/hr

NA: Not Applicable

VII. Alternate Standards Under Consideration

As noted in Section III of this memorandum, the EPA used its discretion not to 

subcategorize by kiln size to develop the proposed standards for non-Hg HAP metals (with PM 

as a surrogate). However, alternate MACT floors were developed for PM to assess the potential 

cost and emission reduction impacts if the EPA did choose to use its discretion to subcategorize 

by kiln size.

Tables 4, 5, and 6 present the number of sources included in the analysis of the alternate

MACT floor options and the alternate existing and new source MACT floor values determined

for the BSCP source category. The rankings for these subcategories are shown in Appendix A, 

the calculation of the subcategory UPL values is shown in Appendix B, the 3xRDL values are 

shown in Appendix C, and the results of the evaluations conducted for limited datasets are shown 

in Appendix D. In addition to these PM MACT floors, the equivalent total non-Hg HAP metals 

limits were calculated as described in Appendix E to be 0.012 lb/hr for existing large and small 

kilns and 0.0018 lb/hr for new large and small kilns. (Note that the total non-Hg HAP metals 

limits are the same for both size subcategories because none of the kilns in the PM MACT floor 
12

pool for small kilns have metals data. Therefore, the total non-Hg HAP metals limit for small 

kilns was set equal to the limit for large kilns.)

Table 4. Number of Sources in the MACT Floor for Alternate Options

Pollutant Subcategory

No. Sources 

Nationwide

No. 

Sources 

with Data

No. Sources 

in MACT Floor 

Pool Based on

PM Large Kilns 122 71 9 12% of sources 

with data

PM Small Kilns 103 21 3 12% of sources 

with data

Table 5. Alternate Existing Source MACT Floors

Subcategory Pollutant Avg. 99% UPL 3xRDL

MACT 

Floor Unit of Measure

Large Kilns PM 0.012 0.028 0.016 0.028 lb/ton

Equivalent PM 0.0045 0.016 0.0077 0.016 gr/dscf @ 7% O2

Small Kilns PM 0.026 0.063 NA 0.063 lb/ton

Equivalent PM 0.0029 0.0050 NA 0.0050 gr/dscf @ 7% O2

NA: Not Applicable

Table 6. Alternate New Source MACT Floors

Subcategory Pollutant Avg. 99% UPL 3xRDL

MACT 

Floor Unit of Measure

Large Kilns PM 0.0060 0.018 0.016 0.018 lb/ton

Equivalent PM 0.0020 0.0059 0.0077 0.0077 gr/dscf @ 7% O2

Small Kilns PM 0.0093 0.029 NA 0.029 lb/ton

Equivalent PM 0.0023 0.0072 NA 0.0040a gr/dscf @ 7% O2

NA: Not Applicable a Limited dataset, see Appendix D.

VIII. References

ASME (founded as the American Society of Mechanical Engineers). 2001. Reference Method 

Accuracy and Precision (ReMAP): Phase 1, Precision of Manual Stack Emission 

Measurements. CRTD Vol. 60, February 2001.

Bhaumik, D.K. and Gibbons, R.D. 2004. “An Upper Prediction Limit for the Arithmetic Mean 

of a Lognormal Random Variable.” Technometrics, 46(2):239-248.
13

Gayen, A. K. 1949. “The Distribution of Student’s t in Random Samples of any Size Drawn 

from Non-Normal Universes.” Biometrika, Vol. 36, No. 3/4 (Dec. 1949), pp. 353-369.

Raymond, G. 2014. Test Data Used in BSCP Proposed Rule. Memorandum from Gabrielle 

Raymond, RTI International, to Jeff Telander, EPA/OAQPS/SPPD. November 6, 2014.

Raymond, G., Sroka, K., and Munoz, B. 2014. Analysis of Potential Subcategories in the BSCP 

Tunnel Kilns. Memorandum from RTI International, to Jeff Telander, EPA/OAQPS/SPPD.

November 6, 2014. 

Telander, J. 2014a. Use of the Upper Prediction Limit for Calculating MACT Floors.

Memorandum from Jeff Telander, EPA/OAQPS/SPPD, to Docket ID No. EPA-HQ-OAR2013-0291. September 9, 2014. 

Telander, J. 2014b. Approach for Applying the Upper Prediction Limit to Limited Datasets.

Memorandum from Jeff Telander, EPA/OAQPS/SPPD, to Docket ID No. EPA-HQ-OAR2013-0291. September 17, 2014.

Westlin, P. and Merrill, R. 2011. Data and procedure for handling below detection level data in 

analyzing various pollutant emissions databases for MACT and RTR emissions limits. 

Memorandum from Peter Westlin, SPPD/MPG and Raymond Merrill, AQAD/MTG, to 

SPPD management and MACT rule writers. December 13, 2011.
Appendix A

MACT Floor Ranking Tables
A-1

MACT Floor Ranking Tables

For each source per pollutant and subcategory, an average emission value was calculated. 

The average emission values for each source per pollutant and subcategory were than ranked by the 

average emission values to determine the best performing sources. The corresponding Appendix A 

Microsoft Excel® files provide the calculations for each source average emission value per 

pollutant and subcategory. They also provide the rankings of the average emission values per 

pollutant and subcategory. The following tables are summary excerpts of the rankings from those 

Microsoft Excel® files. The MACT floor pool in each table includes those kilns listed above the 

bolded line.
A-2

Table A-1. Proposed Standards – PM lb/ton Ranking

Kiln ID

APCD 

Type Size Class Average (lb/ton) Variance

Below 1 mg 

RDL Value n

Rank by 

Average

514 DIFF Large Area Source (synthetic) 0.00604 1.08E-05 yes 3 1

686 DIFF Large Area Source (synthetic) 0.00821 3.67E-06 3 2

687 DIFF Large Area Source (synthetic) 0.00821 3.67E-06 3 3

538 DIFF Large Major Source 0.00868 1.09E-05 yes 5 4

599 DIFF Small Major Source 0.00930 2.99E-05 3 5

508 DIFF Large Major Source 0.01000 1.36E-05 6 6

503 DIFF Large Area Source (synthetic) 0.01399 3.67E-07 3 7

600 DIFF Large Area Source (synthetic) 0.01799 2.98E-04 yes 6 8

604 DLS Large Area Source (synthetic) 0.01843 3.98E-05 3 9

568 DIFF Large Area Source (synthetic) 0.02021 4.79E-05 5 10

688 DIFF Large Area Source (synthetic) 0.03157 1.53E-04 6 11

603 DLS Large Area Source (synthetic) 0.03278 2.23E-04 3 12

558 DIFF Large Major Source 0.03471 1.05E-03 yes 6 13

610 DIFF Large Area Source (synthetic) 0.03732 7.38E-05 6 14

543 DIFF Large Area Source (synthetic) 0.03790 1.10E-03 yes 5 15

606 DIFF Large Major Source 0.03901 1.80E-03 yes 3 16

502 DLS Large Major Source 0.04255 1.48E-03 yes 6 17

544 DIFF Large Area Source (synthetic) 0.04487 1.09E-03 yes 14 18

654 DIFF Large Area Source (synthetic) 0.04500 3.28E-05 3 19

653 DIFF Large Major Source 0.05159 3.21E-05 6 20

547 DIFF Large Major Source 0.05283 1.06E-03 yes 6 21

548 DIFF Large Major Source 0.05283 1.06E-03 yes 6 22

506 DLS Large Area Source (synthetic) 0.05578 4.25E-04 9 23

566 DIFF Large Major Source 0.06024 3.28E-03 yes 8 24

526 DIFF Large Major Source 0.06969 1.05E-03 9 25

527 DIFF Large Major Source 0.07699 6.23E-03 yes 9 26

567 DIFF Large Major Source 0.09304 5.67E-04 3 27

738 DIFF Large Area Source (synthetic) 0.11217 8.58E-03 6 28

675 DIFF Large Area Source (synthetic) 0.14825 1.72E-03 3 29

676 DIFF Large Area Source (synthetic) 0.18995 3.55E-02 6 30

655 DIFF Large Area Source (synthetic) 0.23971 5.23E-02 5 31
A-3

Table A-2. Proposed Standards for Large Kilns – Hg lb/ton Rankinga

Kiln No

APCD 

Type Size Class

Average 

(lb/ton) Variance

Run 

Status n

Rank by 

Average

568 DIFF Large Area Source (synthetic) 1.48E-05 8.83E-13 BDL 3 1

558 DIFF Large Major Source 1.70E-05 1.43E-12 DLL 3 2

655 DIFF Large Area Source (synthetic) 1.72E-05 3.10E-11 ADL 3 3

547 DIFF Large Major Source 2.31E-05 2.33E-11 DLL 3 4

548 DIFF Large Major Source 2.31E-05 2.33E-11 DLL 3 5

676 DIFF Large Area Source (synthetic) 2.70E-05 8.99E-12 DLL 3 6

503 DIFF Large Area Source (synthetic) 2.91E-05 7.63E-12 DLL 3 7

566 DIFF Large Major Source 3.27E-05 2.37E-12 BDL 3 8

606 DIFF Large Major Source 3.85E-05 3.30E-11 DLL 3 9

721 WS Large Area Source (synthetic) 3.93E-05 4.84E-10 DLL 2 10

720 WS Large Area Source (synthetic) 6.22E-05 2.92E-10 DLL 2 11

543 DIFF Large Area Source (synthetic) 7.66E-05 7.09E-12 DLL 3 12

775 None Large Major Source 7.79E-05 1.60E-09 DLL 3 13

526 DIFF Large Major Source 8.50E-05 7.47E-10 ADL 3 14

600 DIFF Large Area Source (synthetic) 8.94E-05 1.08E-10 ADL 3 15

508 DIFF Large Major Source 9.08E-05 1.21E-10 DLL 3 16

527 DIFF Large Major Source 9.08E-05 5.98E-11 ADL 3 17

544 DIFF Large Area Source (synthetic) 9.78E-05 1.02E-10 DLL 3 18

653 DIFF Large Major Source 1.02E-04 9.35E-12 DLL 3 19

a ADL = above detection level; WS = wet scrubber; NA = not applicable.
A-4

Table A-3. Proposed Standards for Small Kilns – Hg lb/ton Rankinga

Kiln No

APCD 

Type Size Class

Average

(lb/ton) Variance

Run 

Status n

Rank by 

Average

531 SD/ESP Small Major Source 1.76E-04 5.51E-11 DLL 3 1

532 SD/ESP Small Major Source 1.76E-04 5.51E-11 DLL 3 2

a SD/ESP = spray dryer/electrostatic precipitator.
A-5

Table A-4. Alternate Standards for Large Kilns – PM lb/ton Rankinga

Kiln ID

APCD 

Type Size Class

Average 

(lb/ton) Variance

Below 1 

mg RDL 

Value n

Rank by 

Average

514 DIFF Large Area Source (synthetic) 0.00604 1.08E-05 yes 3 1

686 DIFF Large Area Source (synthetic) 0.00821 3.67E-06 3 2

687 DIFF Large Area Source (synthetic) 0.00821 3.67E-06 3 3

538 DIFF Large Major Source 0.00868 1.09E-05 yes 5 4

508 DIFF Large Major Source 0.01000 1.36E-05 6 5

695 None Large Major Source 0.01163 4.65E-06 yes 3 6

503 DIFF Large Area Source (synthetic) 0.01399 3.67E-07 3 7

696 DLA Large Major Source 0.01761 1.38E-04 3 8

600 DIFF Large Area Source (synthetic) 0.01799 2.98E-04 yes 6 9

604 DLS Large Area Source (synthetic) 0.01843 3.98E-05 3 10

568 DIFF Large Area Source (synthetic) 0.02021 4.79E-05 5 11

688 DIFF Large Area Source (synthetic) 0.03157 1.53E-04 6 12

603 DLS Large Area Source (synthetic) 0.03278 2.23E-04 3 13

558 DIFF Large Major Source 0.03471 1.05E-03 yes 6 14

673 DLA Large Major Source 0.03627 1.23E-04 6 15

674 DLA Large Major Source 0.03627 1.23E-04 6 16

610 DIFF Large Area Source (synthetic) 0.03732 7.38E-05 6 17

647 DLA Large Area Source (synthetic) 0.03758 1.37E-04 3 18

662 DLA Large Major Source 0.03784 6.66E-04 3 19

543 DIFF Large Area Source (synthetic) 0.03790 1.10E-03 yes 5 20

606 DIFF Large Major Source 0.03901 1.80E-03 yes 3 21

502 DLS Large Major Source 0.04255 1.48E-03 yes 6 22

544 DIFF Large Area Source (synthetic) 0.04487 1.09E-03 yes 14 23

654 DIFF Large Area Source (synthetic) 0.04500 3.28E-05 3 24

583 DLA Large Major Source 0.04765 3.08E-04 3 25

680 DLA Large Major Source 0.04959 6.83E-05 3 26

653 DIFF Large Major Source 0.05159 3.21E-05 6 27

547 DIFF Large Major Source 0.05283 1.06E-03 yes 6 28

548 DIFF Large Major Source 0.05283 1.06E-03 yes 6 29

506 DLS Large Area Source (synthetic) 0.05578 4.25E-04 9 30

649 DLA Large Major Source 0.05658 1.29E-04 3 31
A

-6

Kiln ID

APCD 

Type Size Class

Average 

(lb/ton) Variance

Below 1 

mg RDL 

Valuen

Rank by 

Average

566 DIFF Large Major Source 0.06024 3.28E-03 yes8 32

646 DLA Large Area Source (synthetic) 0.06031 1.08E-043 33

770 DLA Large Major Source 0.06884 1.92E-043 34

526 DIFF Large Major Source 0.06969 1.05E-039 35

527 DIFF Large Major Source 0.07699 6.23E-03 yes9 36

725 DLA Large Area Source (synthetic) 0.07840 1.93E-033 37

691 DLA Large Area Source (synthetic) 0.08227 4.29E-043 38

769 DLA Large Major Source 0.08635 4.66E-043 39

625 DLA Large Major Source 0.09099 5.79E-043 40

567 DIFF Large Major Source 0.09304 5.67E-043 41

721 WS Large Area Source (synthetic) 0.09565 1.82E-035 42

724 DLA Large Area Source (synthetic) 0.09599 7.78E-043 43

641 DLA Large Area Source (synthetic) 0.09977 1.64E-033 44

518 DLA Large Major Source 0.10624 5.28E-043 45

679 DLA Large Major Source 0.10847 3.80E-033 46

738 DIFF Large Area Source (synthetic) 0.11217 8.58E-036 47

573 DLA Large Area Source (synthetic) 0.13228 2.02E-043 48

730 DLA Large Major Source 0.13851 2.63E-036 49

675 DIFF Large Area Source (synthetic) 0.14825 1.72E-033 50

740 DLA Large Area Source (synthetic) 0.15802 2.68E-033 51

517 DLA Large Area Source (synthetic) 0.16373 5.57E-036 52

729 DLA Large Major Source 0.17786 1.91E-033 53

644 DLA Large Major Source 0.17806 9.79E-043 54

676 DIFF Large Area Source (synthetic) 0.18995 3.55E-026 55

736 DLA Large Area source (synthetic) 0.20060 7.15E-033 56

655 DIFF Large Area Source (synthetic) 0.23971 5.23E-025 57

577 DLA Large Major Source 0.24112 1.86E-01 15 58

578 DLA Large Major Source 0.24112 1.86E-01 15 59

645 DLA Large Major Source 0.26210 6.74E-036 60

539 None Large Major Source 0.28166 5.73E-032 61

720 WS Large Area Source (synthetic) 0.32413 1.33E-015 62

768 DLA Large Major Source 0.37699 1.40E-023 63
A-7

Kiln ID

APCD 

Type Size Class

Average 

(lb/ton) Variance

Below 1 

mg RDL 

Value n

Rank by 

Average

643 WS Large Area Source (synthetic) 0.37757 5.25E-02 7 64

612 DLA Large Major Source 0.41284 1.27E-02 3 65

613 DLA Large Major Source 0.41284 1.27E-02 3 66

551 DLA Large Major Source 0.55342 5.04E-02 18 67

552 DLA Large Major Source 0.55342 5.04E-02 18 68

775 None Large Major Source 0.64068 4.38E-02 6 69

766 DLA Large Major Source 0.82067 7.89E-01 6 70

767 DLA Large Major Source 0.82067 7.89E-01 6 71

a WS = wet scrubber; NA = not applicable.
A-8

Table A-5. Alternate Standards for Small Kilns – PM lb/ton Ranking

Kiln ID

APCD 

Type Size Class

Average 

(lb/ton) Variance 

Below 1 

mg RDL 

Value n

Rank by 

Average

599 DIFF Small Major Source 0.00930 2.99E-05 3 1

549 None Small Major Source 0.01960 1.36E-05 3 2

665 None Small Major Source 0.05004 7.63E-05 3 3

663 None Small Major Source 0.05628 3.14E-04 3 4

571 None Small Area Source (synthetic) 0.06847 1.92E-04 3 5

531 SD/ESP Small Major Source 0.11149 6.80E-03 6 6

532 SD/ESP Small Major Source 0.11149 6.80E-03 6 7

533 SD/ESP Small Major Source 0.18153 1.96E-03 3 8

180 None Small Major Source 0.18290 1.06E-03 3 9

521 None Small Major Source 0.23121 1.31E-03 3 10

178 None Small Major Source 0.24311 5.22E-03 3 11

650 None Small Major Source 0.25022 4.06E-03 3 12

516 None Small Major Source 0.29156 7.25E-03 6 13

179 None Small Major Source 0.31288 1.06E-04 3 14

669 None Small Major Source 0.37566 2.73E-04 3 15

529 None Small Major Source 0.38192 1.95E-02 3 16

530 None Small Major Source 0.39455 1.49E-02 9 17

535 None Small Major Source 0.66397 1.98E-02 3 18

706 None Small Major Source 0.74622 2.61E-01 6 19

704 None Small Major Source 1.18767 6.79E-02 3 20

705 None Small Major Source 1.18767 6.79E-02 3 21
Appendix B

UPL Tables
B-1

UPL Tables

Once the best performing sources were identified per pollutant and subcategory, the 

existing and new source UPL values were calculated. The corresponding Appendix B Microsoft

Excel® files provide the calculations for each existing and new source UPL per pollutant and 

subcategory. They also provide a summary of the UPL values per pollutant and subcategory. 

The following tables are summary excerpts of the UPL values from those Microsoft Excel®

files.
B-2

Table B-1. Proposed Standards Existing Source UPL Summary

Subcategory Pollutant

No. of 

Sources 

Industrywide

No. of 

Sources 

with Data

Determination 

of No. of 

Sources in 

MACT Floor

No. of 

Sources 

in MACT 

Floor (N)

No. Data 

Points in 

MACT 

Floor (n)

Average 

of Top 

Sources UPL 

Unit of 

Measure

Data 

Distribution

All Kilns PM 225 31 12% Sources 

Industrywide 27 148 0.041 0.16 lb/ton lognormal

Equivalent PM 225 31 12% Sources 

Industrywide 27 148 0.011 0.040 gr/dscf @ 

7% O2

lognormal

Large Kilns Mercury 122 19 12% Sources 

with Data 3 9 1.6E-05 2.2E-05 lb/ton normal

Equivalent 

Mercury 122 19 12% Sources with Data 3 9 14 29 μg/dscm @ 7% O2

normal

Equivalent 

Mercury 122 19 12% Sources with Data 3 9 1.7E-04 2.7E-04 lb/hr skewed/ unknown

Small Kilns Mercury 103 2 12% Sources 

with Data 1 3 1.8E-04 2.0E-04 lb/ton lognormal

Equivalent

Mercury 103 2 12% Sources with Data 1 3 62 70 μg/dscm @ 7% O2

normal

Equivalent 

Mercury 103 2 12% Sources with Data 1 3 0.0010 0.0011 lb/hr lognormal
B-3

Table B-2. Proposed Standards New Source UPL Summary

Subcategory Pollutant

No. of 

Sources 

Industrywide

No. of 

Sources 

with Data

Determination 

of No. of 

Sources in 

MACT Floor

No. of 

Sources 

in MACT 

Floor (N)

No. Data 

Points in 

MACT 

Floor (n)

Average 

of Top 

Sources UPL 

Unit of 

Measure

Data 

Distribution

All Kilns PM 225 31 12% Sources 

Industrywide 1 3 0.0060 0.018 lb/ton lognormal

Equivalent PM 225 31 12% Sources 

Industrywide 1 3 0.0020 0.0059 gr/dscf @ 

7% O2

lognormal

Large Kilns Mercury 122 19 12% Sources 

with Data 1 3 1.5E-05 2.0E-05 lb/ton normal

Equivalent 

Mercury 122 19 12% Sources with Data 1 3 10 13 μg/dscm @ 7% O2

lognormal

Equivalent 

Mercury 122 19 12% Sources with Data 1 3 0.00018 0.00024 lb/hr normal

Small Kilns Mercury 103 2 12% Sources 

with Data 1 3 1.8E-04 2.0E-04 lb/ton lognormal

Equivalent 

Mercury 103 2 12% Sources with Data 1 3 62 70 μg/dscm @ 7% O2

normal

Equivalent 

Mercury 103 2 12% Sources with Data 1 3 0.0010 0.0011 lb/hr lognormal
B-4

Table B-3. Alternate Standards Existing Source UPL Summary

Subcategory Pollutant

No. of 

Sources 

Industrywide

No. of 

Sources 

with Data

Determination 

of No. of 

Sources in 

MACT Floor

No. of 

Sources 

in MACT 

Floor (N)

No. Data 

Points in 

MACT 

Floor (n)

Average 

of Top 

Sources UPL 

Unit of 

Measure

Data 

Distribution

Large Kilns PM 122 71 12% Sources 

with Data 9 34 0.012 0.028 lb/ton lognormal

Equivalent PM 122 71 12% Sources 

with Data 9 34 0.0045 0.016 gr/dscf @ 

7% O2

skewed/ 

unknown

Small Kilns PM 103 21 12% Sources 

with Data 3 9 0.026 0.063 lb/ton normal

Equivalent PM 103 21 12% Sources 

with Data 3 9 0.0029 0.0050 gr/dscf @ 

7% O2

normal

Table B-4. Alternate Standards New Source UPL Summary

Subcategory Pollutant

No. of 

Sources 

Industrywide

No. of 

Sources 

with Data

Determination 

of No. of 

Sources in 

MACT Floor

No. of 

Sources 

in MACT 

Floor (N)

No. Data 

Points in 

MACT 

Floor (n)

Average 

of Top 

Sources UPL 

Unit of 

Measure

Data 

Distribution

Large Kilns PM 122 71 12% Sources 

with Data 1 3 0.0060 0.018 lb/ton lognormal

Equivalent PM 122 71 12% Sources 

with Data 1 3 0.0020 0.0059 gr/dscf @ 7% O2

lognormal

Small Kilns PM 103 21 12% Sources 

with Data 1 3 0.0093 0.029 lb/ton lognormal

Equivalent PM 103 21 12% Sources 

with Data 1 3 0.0023 0.0072 gr/dscf @ 7% O2

lognormal
Appendix C

Conversion of 3xRDL Values to Units Other Than Concentration to Facilitate Comparison 

with UPL Values
C-1

Conversion of 3xRDL Values to Units Other Than Concentration to Facilitate Comparison 

with UPL Values

The standard 3xRDL values developed for specific pollutants at certain sample volumes 

are presented in a guidance document developed by the EPA (Westlin and Merrill, 2011).

For the BSCP MACT floors, the units of measure used to develop the UPL values were 

lb/ton brick, lb/hr, gr/dscf @ 7% O2, and μg/dscm @ 7% O2. However, the 3xRDL values from 

the guidance document are given in units of concentration, specifically μg/dscm for metals and 

PM. In order to compare the calculated UPL with the 3xRDL for a particular pollutant, we 

needed to convert the 3xRDL value to the units of measure used in the UPL calculation. This 

appendix describes the procedure used for that conversion.

The Appendix C Microsoft Excel® file provides the run-by-run test data and the 

calculations used to convert the 3xRDL values for each pollutant and subcategory. The tables in 

this appendix are summary excerpts of the information from that Microsoft Excel® file.

1. For all of the sources in the MACT floor pool, we looked at each test run that was 

flagged by respondents to the BSCP survey as below detection level (BDL) or detection 

level limited (DLL). If any test runs were BDL or DLL, we proceeded with the following 

steps to convert the 3xRDL value to the units of measure used in UPL. For PM, if any 

run was below the 1 mg RDL value, we also proceeded with the following steps. If all 

runs were above detection level (ADL) and all PM runs were above 1 mg, it was not 

necessary to compare a 3xRDL value to the UPL; instead, we used the UPL value for 

MACT floor. For the BSCP source category, there were values below the 1 mg RDL for 

PM, and values BDL/DLL for Hg.

2. For all of the sources in the PM and Hg MACT existing source floor pools, we compiled

the available concentration, oxygen-corrected concentration, lb/ton, and lb/hr values for 

those sources and noted the sample volume (dscm) for all runs used in the dataset.

3. We calculated the ratio of the run-by-run data for PM lb/ton / μg/dscm; PM gr/dscf @ 7% 

O2 / μg/dscm; Hg lb/ton / μg/dscm; Hg μg/dscm @ 7% O2 / μg/dscm; and Hg lb/hr / 

μg/dscm.

4. We calculated the average of all the ratio values. Table C-1 provides the calculated 

average of all of the ratio values for each pollutant and subcategory.
C-2

Table C-1. Average of All the Run-by-Run Ratios

Option Subcategory Pollutant

Average 

Ratio Units Of Measure

Proposed All Kilns PM 7.37E-06 lb/ton / μg/dscm

PM (equivalent) 2.19E-06 gr/dscf @ 7% O2 / μg/dscm

Large Kilns Hg 4.70E-06 lb/ton / μg/dscm

Hg (equivalent) 3.74E+00 μg/dscm @ 7% O2 / μg/dscm

Hg (equivalent) 4.72E-05 lb/hr / μg/dscm

Small Kilns Hg 1.02E-05 lb/ton / μg/dscm

Hg (equivalent) 3.60E+00 μg/dscm @ 7% O2 / μg/dscm

Hg (equivalent) 1.16E-04 lb/hr / μg/dscm

Alternate Large Kilns PM 5.21E-06 lb/ton / μg/dscm

PM (equivalent) 2.55E-06 gr/dscf @ 7% O2 / μg/dscm

Small Kilns PM NA lb/ton / μg/dscm

PM (equivalent) NA gr/dscf @ 7% O2 / μg/dscm

5. We identified the typical sample volume (in units of dscm) for each dataset. For PM and 

Hg, the typical sample volume was equal to 1 dscm for most BSCP tests.

6. We identified the appropriate 3xRDL concentration values for the typical sample volume 

of the test runs in this dataset (1 dscm) to use from the memorandum Data and procedure 

for handling below detection level data in analyzing various pollutant emissions 

databases for MACT and RTR emissions limits (Westlin and Merrill, 2011). Table C-2 

displays the appropriate 3xRDL concentration values for PM and Hg at the typical 

sample volume of 1 dscm and other various dscm tests.

Table C-2. 3xRDL Values from Guidance Document (Westlin and Merrill, 2011)

Pollutant RDL (μg)

3xRDL 

(μg)

3xRDL Concentrations (μg/dscm)

1 dscm test 2 dscm test 3 dscm test 4 dscm test

PM filterable 

(Method 5) 1.0E+03 3.0E+03 3.0E+03 1.5E+03 1.0E+03 7.5E+02

Mercury (Method 29) 

analyzed by Cold 

Vapor AA

5.6E-01 1.7E+00 1.7E+00 8.4E-01 5.6E-01 4.2E-01
C-3

7. We multiplied the appropriate 3xRDL concentration value for the typical sample volume by the average ratio in Table C-1 to 

convert the 3xRDL value into the units of measure used in the UPL calculation (e.g., lb/ton; lb/hr; gr/dscf @7% O2; or 

μg/dscm @7% O2). Table C-3 displays a summary of the converted 3xRDL values.

Table C-3. Converted 3xRDL Values

Option Subcategory Pollutant

Average 

Ratio

Average Ratio Units Of 

Measure

3xRDL at 

Typical 

Sample 

Volume 

(μg/dscm)

Converted 

3xRDL 

Value

Converted 

3xRDL Value 

Units Of 

Measure

Proposed All Kilns PM 7.37E-06 lb/ton / μg/dscm 3.0E+03 0.022 lb/ton

PM (equivalent) 2.19E-06 gr/dscf @ 7% O2 / μg/dscm 3.0E+03 0.0066 gr/dscf @ 7% O2

Large Kilns Hg 4.70E-06 lb/ton / μg/dscm 1.7E+00 7.99E-06 lb/ton

Hg (equivalent) 3.74E+00 μg/dscm @ 7% O2 / μg/dscm 1.7E+00 6.4 μg/dscm @ 7% O2

Hg (equivalent) 4.72E-05 lb/hr / μg/dscm 1.7E+00 8.0E-05 lb/hr

Small Kilns Hg 1.02E-05 lb/ton / μg/dscm 1.7E+00 1.7E-05 lb/ton

Hg (equivalent) 3.60E+00 μg/dscm @ 7% O2 / μg/dscm 1.7E+00 6.1 μg/dscm @ 7% O2

Hg (equivalent) 1.16E-04 lb/hr / μg/dscm 1.7E+00 2.0E-04 lb/hr

Alternate Large Kilns PM 5.21E-06 lb/ton / μg/dscm 3.0E+03 0.016 lb/ton

PM (equivalent) 2.55E-06 gr/dscf @ 7% O2 / μg/dscm 3.0E+03 0.0077 gr/dscf @ 7% O2

Small Kilns PM NA lb/ton / μg/dscm NA NA lb/ton

PM (equivalent) NA gr/dscf @ 7% O2 / μg/dscm NA NA gr/dscf @ 7% O2
C-4

8. We compared the 3xRDL value to the calculated UPL.

a. If the 3xRDL value was less than or equal to the calculated UPL value, we used the UPL value as the MACT floor 

emission limit.

b. If the 3xRDL value was greater than the calculated UPL value, we used the 3xRDL value as the MACT floor emission 

limit.

c. Table C-4 and C-5 summarize the results of the calculated UPL and 3xRDL comparison for existing and new source 

floors.

Table C-4. Existing Source Floors

Option Subcategory Pollutant

Converted 

3xRDL Valuea UPL Floor

Floor Based 

On Units Of Measure

Proposed All Kilns PM 0.022 0.16 0.16 UPL lb/ton

PM (equivalent) 0.0066 0.040 0.040 UPL gr/dscf @ 7% O2

Large Kilns Hg 7.99E-06 2.2E-05 2.2E-05 UPL lb/ton

Hg (equivalent) 6.4 29 29 UPL μg/dscm @ 7% O2

Hg (equivalent) 8.0E-05 2.7E-04 2.7E-04 UPL lb/hr

Small Kilns Hg 1.7E-05 2.0E-04 2.0E-04 UPL lb/ton

Hg (equivalent) 6.1 70 70 UPL μg/dscm @ 7% O2

Hg (equivalent) 2.0E-04 0.0011 0.0011 UPL lb/hr

Alternate Large Kilns PM 0.016 0.028 0.028 UPL lb/ton

PM (equivalent) 0.0077 0.016 0.016 UPL gr/dscf @ 7% O2

Small Kilns PM NA 0.063 0.063 UPL lb/ton

PM (equivalent) NA 0.0050 0.0050 UPL gr/dscf @ 7% O2

a NA: Not Applicable if all runs in the MACT floor pool were ADL for Hg and above the 1 mg RDL value for PM.
C-5

Table C-5. New Source Floors

Option Subcategory Pollutant

Converted 

3xRDL Valuea UPL Floor

Floor Based 

On Units Of Measure

Proposed All Kilns PM 0.022 0.018 0.022 3xRDL lb/ton

PM (equivalent) 0.0066 0.0059 0.0066 3xRDL gr/dscf @ 7% O2

Large Kilns Hg 7.99E-06 2.0E-05 2.0E-05 UPL lb/ton

Hg (equivalent) 6.4 13 13 UPL μg/dscm @ 7% O2

Hg (equivalent) 8.0E-05 2.4E-04 2.4E-04 UPL lb/hr

Small Kilns Hg 1.7E-05 2.0E-04 2.0E-04 UPL lb/ton

Hg (equivalent) 6.1 70 70 UPL μg/dscm @ 7% O2

Hg (equivalent) 2.0E-04 0.0011 0.0011 UPL lb/hr

Alternate Large Kilns PM 0.016 0.018 0.018 UPL lb/ton

PM (equivalent) 0.0077 0.0059 0.0077 3xRDL gr/dscf @ 7% O2

Small Kilns PM NA 0.029 0.029 UPL lb/ton

PM (equivalent) NA 0.0072 0.0072 UPL gr/dscf @ 7% O2

a NA: Not Applicable if all runs in the MACT floor pool were ADL for Hg and above the 1 mg RDL value for PM.
Appendix D

Limited Datasets
D-1

For the BSCP source category, we have limited datasets for the following pollutants and 

subcategories: Hg for existing and new small tunnel kilns; PM for new all tunnel kilns; and Hg 

for new large tunnel kilns. For the BSCP alternate options, we have limited datasets for the 

following pollutants and subcategories: PM for new large tunnel kilns and PM for new small 

tunnel kilns. We evaluated these specific datasets to determine whether it is appropriate to make 

any modifications to the approach used to calculate MACT floors for each of these datasets.

For each dataset, we performed the following steps: ensuring that we selected the data 

distribution that best represents each dataset; ensuring that the correct equation for the 

distribution was then applied to the data; and comparing individual components of each limited 

dataset to determine if the standards based on limited datasets reasonably represent the 

performance of the units included in the dataset (Telander, 2014b). 

We determined that no changes to our standard floor calculation procedure were 

warranted and are proposing the MACT floor limits as calculated. We did determine that further 

evaluation of the best performing unit for the alternate option limit for PM for new small tunnel 

kilns was needed (Telander, 2014b). We reevaluated the best performing unit for that option and 

found that another unit better represents the best performing unit. As such, the MACT floor is 

0.0040 gr/dscf @ 7% O2 for PM from alternate new small tunnel kilns (Telander, 2014b). The 

Appendix D Microsoft Excel® file provides additional information about the reevaluation of the 

best performing unit. 
Appendix E

Development of Conversion Factors Used to Determine Total Non-Hg HAP Metals Limit
E-1

Development of Conversion Factors Used to Determine Total Non-Hg HAP Metals Limit

The BSCP dataset included limited data for non-Hg HAP metals. Of the 27 sources in 

the top 12 percent of the proposed PM MACT floor pool, only nine sources had viable metals 

data. (Four other sources had metals data that had to be removed due to two or more manganesecontaminated runs.) Of the nine sources in the top 12 percent of the alternate PM MACT floor 

pool for large kilns, only one source has viable metals data. (Two other sources had metals data 

that had to be removed due to two or more manganese-contaminated runs.) Of the three sources 

in the top 12 percent of the alternate PM MACT floor pool for small kilns, there were no sources 

with metals data. For more information on the identification and treatment of manganesecontaminated runs, see Test Data Used in BSCP Proposed Rule (Raymond, 2014).

Therefore, in order to develop a total non-Hg HAP metals limit equivalent to the MACT 

floors developed for PM, we needed to develop conversion factors to convert the PM MACT 

floor limits to total non-Hg HAP metals limits. The following steps were used to develop the 

conversion factors and the total non-Hg HAP metals limits equivalent to the existing source PM 

MACT floors. The Appendix E Microsoft Excel® file includes the compiled data for sources in 

the MACT floor pool and the results of the calculations in the steps below. Tables E-1 and E-2 

are summary excerpts of the information from that Microsoft Excel® file.

Step 1. Compiled the production rate (tph), PM emission rate (lb/hr), and total non-Hg 

HAP metals emission rate (lb/hr) from kilns in the MACT floor pool for the PM limit.

Step 2. Calculated the percent total non-Hg HAP metals in the PM by dividing the total 

non-Hg HAP metals lb/hr value by the PM lb/hr value for each simultaneous run with data.

Step 3. Calculated the average percentage of PM that is non-Hg HAP metals.

Step 4. Calculated the average production rate.

Step 5. Multiplied the PM MACT floor value (lb/ton) by the average production rate 

(tph) to convert from PM in lb/ton to PM in lb/hr.

Step 6. Multiplied the PM lb/hr by the average percent total non-Hg HAP metals in the 

PM to convert from PM in lb/hr to total non-Hg HAP metals in lb/hr.
E-2

Table E-1. Existing Source Total Non-Hg HAP Metals lb/hr Limit (Equivalent to PM Floor)

Standards

MACT Floor

(lb/ton)

Average Percent 

Total Non-Hg 

HAP Metals

Average 

Production Rate 

(tph)

Total Non-Hg HAP 

Metals lb/hr Limita

Proposed 0.16 1.36 10.54 0.023

Alternate, Large Kilns 0.028 1.81 13.30 0.0068

Alternate Small Kilns 0.063 NA NA 0.0068b

a Results are rounded at the end of the calculations. b None of the kilns in the small kiln PM MACT floor have metals data; therefore, the non-Hg HAP metals limit for small 

kilns is set equal to the limit for large kilns.

The conversion of the new source PM limit to an equivalent total non-Hg HAP metals 

limit was calculated slightly differently because the best performing unit in the PM new source 

MACT floor pool did not have any non-Hg HAP metals data. The best performing unit has a 

DIFF control device, so we used the production rates and percent non-Hg HAP metals in the PM 

from other DIFF kilns in the proposed existing source MACT floor pool; these are the same 

conversion factors used for the proposed existing limit conversion. The results are presented in 

Table E-2.

Table E-2. New Source Total Non-Hg HAP Metals lb/hr Limit (Equivalent to PM Floor)

Option

MACT Floor

(lb/ton)

Average Percent 

Total Non-Hg 

HAP Metals

Average 

Production Rate 

(tph)

Total Non-Hg HAP 

Metals lb/hr Limita

Proposed 0.022 1.36 10.54 0.0032

Alternate Large 0.018 1.36 10.54 0.0026

Alternate Small 0.029 NA NA 0.0026b

a Results are rounded at the end of the calculations. b None of the kilns in the small kiln PM MACT floor have metals data; therefore, the non-Hg HAP metals limit for small 

kilns is set equal to the limit for large kilns.