1 **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 statu s 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 co mbined 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 6 th 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- 132 shows that Kiln No. 9 is the 6 th 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 t he Kiln No. and Kohler’s Kiln IDs, which can be used as a cross - reference. **Kiln No Parent Co.**  **City State**  **Kiln ID AP**  **CD Ty pe**  **Stack/A PCD_ID**  2 Kohler Co. Spartanburg SC 02 - TK-2 None CO1S (POC), EE, FE, RCE, WC E (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)3 **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 ki lns, 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, t statistic, 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 litt le 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, particulat e 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 -044 **D/F TEQ ng/dscm @ 7% O**  **2 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 kiln a**  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 5 th 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 avera ging 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 so ak 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 al ready 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).5 **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 1 st 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 g laze 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 equ ipment 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 a n 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 sp ray 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 n o 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 ongoi ng basis (as applicable) and the emissions limit is not exceeded during the next performance test.6  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 limita tion (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 proc ess 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 establi shed 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 kil ns 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 exp ensive 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 cerami cs test data memo). Consequently, e missions 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% 0.22 5 74% 2 2.39E - 02 96% < 8.06E - 03 56% 0.17 4 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% 0.067 9 28%7 **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% 0.071 9 28% TK #10 POC + RCE stacks 1 1.78E - 02 1.43E - 02 0.30 3 2 2.50E - 02 < 1.43E - 02 0.241 3 2.36E - 02 < 1 . 40 E - 02 0.258 TK #2 POC stack 1 1.69E - 01 97% 7.99E - 03 74% 0.090 8 57% 2 1.31E - 01 98% 9.26E - 03 78% 0.086 1 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% 0.029 5 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% 0.037 8 24% 2 2.73E - 03 2% 2.48E - 03 21% 0.0135 13% 3 1.57E - 03 2% 2.70E - 03 19% 0.0089 4 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 0.1 30 Stacks: POC = P roducts of C ombustion stack EE = Entrance Ex haust 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 c lay 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 i ndication 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 sho uld 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?8 Response : We discussed in the preamble ( 7 9 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 1 st fire ware, even though they are permitted to, will not be subject, unless they start to process 1 st fire ware.