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Compilation of Kohler Questions, with Responses

Kohler questions—December 2, 2014:

 In the MACT floor memo, Appendix A, run status is shown as DLL (detection level limited) or 

ADL. What does ADL stand for? Above detection level?

Response: ADL stands for Above Detection Limit

 I see no status shown as BDL (below detection level).

Response: For Table A-12 (Sanitaryware TK Hg) the “Run Status” (i.e. the overall status of that 

kiln) was determined by first identifying the status of each of the five mercury fractions for each 

run. If all five Hg fractions were ADL, then the status of that particular run was ADL. If all five Hg 

fractions were BDL, then the status of that run was BDL. If there was a mix of ADL and BDL 

within the five Hg fractions, then the status of that run was DLL. Next, the status of all test runs 

for each kiln was compared. If the status of all test runs was ADL, then the overall status of that 

kiln was ADL. If the status of all test runs was BDL, then the overall status of that kiln was BDL. If 

there was a mix of ADL and BDL within all test runs, then the overall status of that kiln was DLL. 

For sanitaryware tunnel kilns, there were no runs where all five Hg fractions of all test runs were 

BDL. 

Similarly, for Table A-14 (Sanitaryware TK D/F TEQ), the status of each individual D/F TEQ 

congener for each run was first evaluated, then each run status to get the final overall “Run 

Status.” 

 Also, I see no wet scrubber (kiln no 9) data in table A-12, but do see it listed in tables A-13 and 

A-14. Why was it omitted as a source for A-12 (Hg)?

Response: Table A-12: Proposed Standards for First-fire Sanitaryware Tunnel Kilns – Hg lb/ton 

Ranking for Hg did omit kiln no. 9 (TK#10 POC + RCE stacks, Kohler Co., Spartanburg, SC). The 

Method 29 results were not used for this kiln because of a mix-up during the analytical 

procedures, specifically the digestion process (see Section 4.1: Analytical discrepancy of the Test 

Report “Kohler Co., Spartanburg, SC: Tunnel Kilns and Glaze Spray Booths 08/11-17/2010 Stack 

Test,” pdf page 32). The Run 3 POC stack sample was compromised, and the Run 1 and Run 2 

RCE stack samples were compromised. Since there was not one combined POC+RCE stack run 

where either the POC or RCE stack sample was not compromised, the Method 29 data for kiln 

no 9 were omitted. 

Run TK#10 POC stack TK#10 RCE stack

1 Compromised

2 Compromised

3 Compromised

 Also, the wet scrubber kiln is ranked as 6th in table A-13 (PM), does this mean it was omitted 

from the floor evaluation? 

Response: That is correct. For the sanitaryware tunnel kiln category, there are <30 sources 

nationwide. CAA Section 112(d)(3) states that for categories with <30 sources nationwide, the 

best performing 5 sources with data are to be used for the MACT floor evaluation. Table A-13 
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shows that Kiln No. 9 is the 6th ranked kiln and is, therefore, not included in the MACT floor 

evaluation. 

 Finally, is there a cross-reference for the sanitaryware kilns so I can know which kiln number in 

your analysis corresponds to which kiln at my facilities?

Response: Appendix B: Final Run-by-Run Values to the memorandum "Test Data Used in Clay 

Ceramics Proposed Rule" contains both the Kiln No. and Kohler’s Kiln IDs, which can be used as a 

cross-reference.

Kiln No Parent Co. City State Kiln ID APCD Type Stack/APCD_ID

2 Kohler Co. Spartanburg SC 02 - TK-2 None CO1S (POC), EE, FE, RCE, 

WCE (5 stacks)

3 Kohler Co. Spartanburg SC TK-3 None CO1S

7 Kohler Co. Spartanburg SC 18 - TK-8 None AO8S (POC), RCE, EXE (3 

stacks)

9 Kohler Co. Spartanburg SC 38 - TK-10 Wet Scrubber 

(since removed)

POC, RCE (2 stacks)

19 Kohler Co. Brownwood TX TK-6 None E247A (combined POC stack), 

CE1-3 (4 stacks)

20 Kohler Co. Brownwood TX TK-12 None E247A (combined POC stack), 

CE (2 stacks)

21 Kohler Co. Kohler WI TK-2 None S24

22 Kohler Co. Kohler WI TK-3 None S24

23 Kohler Co. Kohler WI TK-4 None S24

26 Kohler Co. Kohler WI TK-7 None S24

33 Kohler Co. Kohler WI TK-19 None S24 (POC), RCE, EE (3 stacks)
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Kohler questions—December 8, 2014:

 In the same document [MACT floor memo], in Table A-14, Kiln #2 is not listed. Why was it 

omitted as a source for D/F. 

Response: The TK# 2 D/F TEQ concentration values were removed from the dataset as a result 

of outlier testing. This is noted in the “Test Data Used in Clay Ceramics Proposed Rule” 

memorandum.

 Also, the analyses presented in these tables (A-12 through A-14) show kilns 19 and 20 as 

separate sources with the exact same average emission rate and variance. As these two kilns 

exhaust through the same stack, they were tested simultaneously. Should they be treated as a 

single kiln since a single exhaust was tested? Does treating them as two distinct kilns, with 

identical emission rates and variability, minimize the variability calculated via the UPL approach, 

resulting in a lower emission limit for sanitaryware kilns than would be the case otherwise?

Response: The kilns were treated as two distinct kilns vs. a single kiln to be consistent with the 

methodology used in both Brick and Floor Tile. The same methodology for each sanitaryware 

tunnel kiln pollutant MACT floor was used, treating units going to the same stack as distinct 

kilns. 

There are several components of the UPL equation that have an effect on the final UPL value--

the average of the data in the MACT floor pool, variability of the data in the MACT floor pool, tstatistic, and "m" future compliance term. Adjusting any one of these can affect the values of 

the other terms and the final UPL value.

In general, the variability within the test runs for the unit affects the variability of the entire 

MACT pool. If the run-by-run data of the unit has little variability, then removing the duplicate 

kiln from the MACT floor pool will usually increase the overall variance and increase the UPL 

value. If the run-by-run data of the unit has significant variability, then removing the duplicate 

kiln from the MACT floor pool will usually decrease the overall variance and decrease the UPL 

value. 

For sanitaryware kilns 19 and 20, treating them as two distinct kilns vs. a single kiln does not 

result in significant differences in the final UPL for mercury, particulate matter, or TEQ, see the 

following tables.

Hg lb/ton Counting as two distinct kilns Counting as single kiln

Distribution Normal Normal 

N 5 4 (no other units with data available to be 

pulled into top 5)

n 15 12

Average 1.64E-04 1.56E-04

Pooled Variance 3.35E-09 3.90E-09

t-statistic 2.62 2.72

m 3 3

UPL 2.6E-04 2.7E-04
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D/F TEQ ng/dscm 

@ 7% O2 Counting as two distinct kilns Counting as single kiln

Distribution Normal Normal 

N 5 4 (no other units with data available to be 

pulled into the MACT floor pool)

n 15 12

Average 8.06E-01 7.07E-01

Pooled Variance 1.63E-01 1.53E-01

t-statistic 2.62 2.72

m 3 3

UPL 1.5 1.4

PM lb/ton Counting as two distinct kilns Counting as single kilna

Distribution Skewed Lognormal 

N 5 5 (next kiln with data available [TK#10] 

pulled into top 5)

n 15 18

Average 1.19E-01 1.55E-01

Pooled Variance 6.45E-03 8.17E-03

t-statistic 4.17 (adjusted for skewed 

distribution)

Lognormal equation uses z-statistic, 3.484

m 3 3

UPL 0.33 0.34

a

Counting as a single kiln opens up the 5th spot in the MACT floor pool; this results in the next kiln being 

added to the MACT floor pool to make 5; the addition of this kiln's data changes the distribution of the 

data in the MACT floor pool from skewed to lognormal, which changes the UPL calculation. 

 In Table 2 of the proposal, item 4 proposes to limit the averaging kiln operating temperature at 

or above the temperature established during the D/F performance test, while item 5 proposes 

to limit the averaging kiln operating temperature at or below the temperature established 

during the D/F performance test. These proposals for D/F seem contradictory; is one a 

typographical error? Also, is the “average kiln operating temperature” the temperature in the 

soak zone (peak temperature zone) of the TK? I assume this requirement doesn’t make the kiln 

operator calculate an average temperature across all kiln zones, and then average these 

averages. I think the TK temperature requirement needs to be clarified as to intent.

Response: Yes, it is a typographical error. Items 4 and 5 in Table 2 to Subpart KKKKK of Part 63 

should both say “at or above” for kilns. And yes, the average kiln operating temperature is the 

kiln soak/peak temperature. 

 Once the proposal is published, how do I request an extension to the 60-day comment period? I 

assume I wouldn’t submit it to the docket, so would it be sent directly to Sharon Nizich? What is 

the Agency’s turn-around time on extension requests?

Response: This question has already been addressed. The end of the public comment period has 

been extended from February 17, 2015 to March 19, 2015 (79 FR 78768, December 31, 2014).
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Kohler questions—December 11, 2014:

 Spray booth emission limits: Proposed limits apply only to 1 fire glaze booths? It’s clear this is 

the intent from the information in the 11/6/14 memo “MACT Floor Analysis for Clay Ceramics” 

from RTI to EPA, but this intent is not so clear in the proposed MACT. 

Response: Yes, the proposed limits for spray glaze booths apply only to 1st fire glaze booths. If 

this proposed exemption of second fire glazing stays in the final rule, we will make sure it is clear 

in the reg text.

 Spray booth emission limits: Proposed limits are based on tons glaze sprayed. Is per ton of 

glaze sprayed on a dry basis or wet basis? I believe we reported all of ICR test results as dry 

basis glaze sprayed.

Response: Yes, the tons glaze sprayed is on a dry basis. If this approach continues into the final 

rule, we will clarify in the reg text.

 Spray booth emission limits: Proposed limits apply to spray booths using only 1F glaze 

containing >0.1% metal HAP. Is this an average of glaze used in a booth or does it apply to any 

color? For instance, most of our glazes are <0.1% HAP. If due to equipment breakdown or other 

reason a facility needs to spray some glaze color that contains >0.1% in a booth for 1 work shift, 

say once per year, does this make this booth subject to the MACT rule and the emission 

limitation? 

Response: The 0.1% metal HAP is an average of glaze used in a booth, and would include all 

colors used in that booth. The average would be on an annual basis, consistent with the 

information requested in the section 114 survey. We will clarify this in the final rule. Since it 

would be an annual basis, spraying a glaze color with >0.1% metal HAP for just 1 work shift 

would not be enough on an annual basis to make this booth subject to the MACT rule and 

emission limitation.

 Spray booth emission limits: Does the process throughput during the performance test become 

the defacto throughput limitation going forward? For instance, if a spray booth is permitted to 

apply 250 dry lbs/hr glaze, but due to production considerations, is able to only spray 175 lbs/hr 

during the performance test, is 175 lbs/hr the new spray limit? If so, what if emissions 

measured 40% of the limitation (though throughput was 70% of capacity) in a performance test, 

would the source have any options to spray more glaze than done in the performance test 

considering there’s little indication the limitation could be exceeded?

Response: There is no throughput limit for spray booths in the proposed rule. However, the 

operating limits for spray booths (Table 2 to Subpart KKKKK of Part 63) would be established 

during the initial performance test, so you would have to meet the operating limits established 

at the throughput used during that test. If the operating conditions change and the previous 

conditions are no longer representative (e.g., change in throughput from 175 to 250 lb/hr), you 

could always retest to establish new operating limits at the higher throughput. However, it is 

advisable to go ahead and conduct the initial test at the highest representative throughput, to 

avoid additional testing and account for production scenarios when higher throughput is 

needed. Since there is no throughput limit in the proposed rule, you could spray more glaze, as 

long as the operating limits are not exceeded on an ongoing basis (as applicable) and the 

emissions limit is not exceeded during the next performance test.
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 1F Tunnel kiln emission limits: Does the process throughput during the performance test 

become the defacto throughput limitation going forward? For instance, if a tunnel kiln is 

permitted to process 3 tons greenware/hr, but due to production considerations, only fires 2 

tons/hr during the performance test, is 2 tons/hr the new kiln throughput limit? If so, what if 

emissions measured 40% of the limitation (though throughput was 67% of capacity) in a 

performance test, would the source have any options to spray more glaze than done in the 

performance test considering there’s little indication the limitation could be exceeded? This 

same question applies to kiln process parameters like temperature. Variability is an element of 

performance and source operators need some flexibility for source operation when there’s no 

indication that an emission limit can be exceeded. Vitreous plants are highly integrated and 

totally dependent on the processes up and down the process line. You cannot just flip a switch 

to make a tunnel kiln process more ware for a few days of testing, then flip the switch back 

off. Increasing production requires an increase at every process step along the way, and it takes 

considerable time to effect process rate changes.

Response: There is a throughput operating limit in the proposed rule for uncontrolled tunnel 

kilns (item 5b in Table 2 to Subpart KKKKK of Part 63) that would be established during the initial 

performance test that you would be required to meet on an ongoing basis (e.g., 2 tons/hr). 

There are also other operating limits that you would have to meet, which would be established 

at the throughput used during the initial test. If the operating conditions change and the 

previous conditions are no longer representative (e.g., change in throughput from 2 to 3 

tons/hr), you could always retest to establish a new operating limit for throughput and new 

operating limits for the other parameters at the higher throughput. However, it is advisable to

go ahead and conduct the initial test at the highest representative throughput, to avoid 

additional testing, account for production scenarios when higher throughput is needed, and 

provide a compliance cushion. For controlled tunnel kilns (no throughput operating limit), you 

could increase throughput, as long as the operating limits are not exceeded on an ongoing basis 

(as applicable) and the emissions limit is not exceeded during the next performance test. For 

uncontrolled tunnel kilns (required throughput operating limit), you could not exceed that 

throughput operating limit.

 1F Tunnel kiln emission limits: Do the limits apply to all kiln stacks combined or just to the POC 

stack? Tunnel kilns by design have a POC stack as the primary kiln chamber exhaust point, and 

then an additional 2 or 3 stacks for cooling air exhaust. Virtually all of the regulated pollutants 

are emitted from the POC stack. Performance testing the cooling stacks is expensive with no 

benefit. 

Response: The available test data for Kohler-Spartanburg, including the POC, EE, FE, and RCE 

stacks, show emissions coming from the non-POC stacks (see summary table below; for more 

information, see Appendix B to the clay ceramics test data memo). Consequently, emissions 

from those stacks were included with emissions from POC stacks to determine the MACT limits.

Stack Run

HF HCl PM

lb/ton

% of total 

stack HF lb/ton

% of total 

stack HCl lb/ton

% of total 

stack PM

TK #10 POC stack 1 1.68E-02 94% 8.33E-03 58% 0.225 74%

2 2.39E-02 96% < 8.06E-03 56% 0.174 72%

3 2.28E-02 96% < 8.00E-03 57% 0.186 72%

TK #10 RCE stack 1 1.05E-03 6% < 5.96E-03 42% 0.0784 26%

2 1.10E-03 4% < 6.24E-03 44% 0.0679 28%
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Stack Run

HF HCl PM

lb/ton

% of total 

stack HF lb/ton

% of total 

stack HCl lb/ton

% of total 

stack PM

3 < 8.28E-04 4% < 6.02E-03 43% 0.0719 28%

TK #10 POC + RCE stacks 1 1.78E-02 1.43E-02 0.303

2 2.50E-02 < 1.43E-02 0.241

3 2.36E-02 < 1.40E-02 0.258

TK #2 POC stack 1 1.69E-01 97% 7.99E-03 74% 0.0908 57%

2 1.31E-01 98% 9.26E-03 78% 0.0861 84%

3 1.00E-01 98% 1.12E-02 80% 0.120 93%

TK #2 EE stack 1 2.70E-05 0% 8.10E-05 1% 0.0295 19%

2 < 1.11E-05 0% < 8.10E-05 1% 0.00244 2%

3 < 1.11E-05 0% < 8.10E-05 1% 0.000756 1%

TK #2 FE stack 1 5.40E-03 3% 2.70E-03 25% 0.0378 24%

2 2.73E-03 2% 2.48E-03 21% 0.0135 13%

3 1.57E-03 2% 2.70E-03 19% 0.00894 7%

TK #2 POC + EE + FE stack 1 1.75E-01 1.08E-02 0.158

2 1.34E-01 1.18E-02 0.102

3 1.02E-01 1.39E-02 0.130

Stacks:

POC = Products of Combustion stack

EE = Entrance Exhaust stack

FE = Fume Exhaust stack

RCE = Rapid Cool Exhaust stack

< = non-detect; used detection limit

 1F Tunnel kiln emission limits: What is the compliance assurance achieved by requiring daily VE 

reading on tunnel kiln stacks. All of our 1F tunnel kilns are NG fired (propane as backup). There 

is no processing of materials in kilns. Sprayed greenware is carefully placed on kiln cars, and kiln 

cars are carefully transported from the kiln entrance to the kiln exit. Nothing about the process 

generates any particulate emissions. VE readings do not provide any indication of kiln operation 

and so add no value to compliance assurance.

Response: For kilns with a fabric filter-based control device (e.g., FF, DIFF, or DLS/FF), VE checks 

(i.e., Method 22 visible emissions tests) were included as a low-cost alternative to bag leak 

detection systems to demonstrate compliance with the PM emissions limit. VE checks were also 

included for uncontrolled kilns to demonstrate compliance with the PM limit. Regarding the 

question about particulate emissions, the available test data for Kohler facilities (see Appendix B 

to the clay ceramics test data memo) show PM emissions from tunnel kilns. Regardless, PM is 

being regulated as a surrogate for non-mercury HAP metal emissions from tunnel kilns, and the 

available test data for Kohler facilities also show metals emissions from tunnel kilns. Regarding 

the compliance value of VE checks, they are not meant to provide an indication of kiln 

operation, but an indication of whether particulates (as a surrogate for non-HAP metals) are 

being emitted from a stack. 

 Shuttle Kilns: We use shuttle kilns to refire ware. That said, many of our shuttle kilns are 

permitted to first fire ware as a contingency measure should we need the flexibility to do so, 

such as might be needed with a tunnel kiln breakdown. If a shuttle kiln does not, and has not, 

processed 1F ware, even though it is permitted to, is it subject to the MACT?
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Response: We discussed in the preamble (79 FR 75651) that kilns that are used exclusively for 

refiring or setting glazes on previously fired products are not subject to the rule. After the 

comment period ends, we may clarify, if appropriate, in the final rule that those shuttle kilns 

that do not process 1st fire ware, even though they are permitted to, will not be subject, unless 

they start to process 1st fire ware.