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Subpart CC—Soda Ash Manufacturing

§98.290 Definition of the source category.

(a) A soda ash manufacturing facility is any facility with a manufacturing line that 

produces soda ash by one of the methods in paragraphs (a)(1) through (3) of this section:

(1) Calcining trona.

(2) Calcining sodium sesquicarbonate.

(3) Using a liquid alkaline feedstock process that directly produces CO2.

(b) In the context of the soda ash manufacturing sector, “calcining” means the 

thermal/chemical conversion of the bicarbonate fraction of the feedstock to sodium carbonate.

§98.291 Reporting threshold.

You must report GHG emissions under this subpart if your facility contains a soda ash 

manufacturing process and the facility meets the requirements of either §98.2(a)(1) or (a)(2).

§98.292 GHGs to report.

You must report:

(a) CO2 process emissions from each soda ash manufacturing line combined.

(b) CO2 combustion emissions from each soda ash manufacturing line.

(c) CH4 and N2O combustion emissions from each soda ash manufacturing line. You 

must calculate and report these emissions under subpart C of this part (General Stationary Fuel 

Combustion Sources) by following the requirements of subpart C.

(d) CO2, CH4, and N2O emissions from each stationary combustion unit other than soda 

ash manufacturing lines. You must calculate and report these emissions under subpart C of this 

part (General Stationary Fuel Combustion Sources) by following the requirements of subpart C.

§98.293 Calculating GHG emissions.
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You must calculate and report the annual process CO2 emissions from each soda ash 

manufacturing line using the procedures specified in paragraph (a) or (b) of this section.

(a) For each soda ash manufacturing line that meets the conditions specified in 

§98.33(b)(4)(ii) or (b)(4)(iii), you must calculate and report under this subpart the combined 

process and combustion CO2 emissions by operating and maintaining a CEMS to measure CO2

emissions according to the Tier 4 Calculation Methodology specified in §98.33(a)(4) and all 

associated requirements for Tier 4 in subpart C of this part (General Stationary Fuel Combustion 

Sources).

(b) For each soda ash manufacturing line that is not subject to the requirements in 

paragraph (a) of this section, calculate and report the process CO2 emissions from the soda ash 

manufacturing line by using the procedure in either paragraphs (b)(1), (b)(2), or (b)(3) of this 

section; and the combustion CO2 emissions using the procedure in paragraph (b)(4) of this 

section.

(1) Calculate and report under this subpart the combined process and combustion CO2

emissions by operating and maintaining a CEMS to measure CO2 emissions according to the Tier 

4 Calculation Methodology specified in §98.33(a)(4) and all associated requirements for Tier 4 

in subpart C of this part (General Stationary Fuel Combustion Sources).

(2) Use either Equation CC-1 or Equation CC-2 of this section to calculate annual CO2

process emissions from each manufacturing line that calcines trona to produce soda ash:

Where:
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Ek = Annual CO2 process emissions from each manufacturing line, k (metric tons).

(ICT)n = Inorganic carbon content (percent by weight, expressed as a decimal fraction) in 

trona input, from the carbon analysis results for month n. This represents the ratio of trona to 

trona ore.

(ICsa)n = Inorganic carbon content (percent by weight, expressed as a decimal fraction) in 

soda ash output, from the carbon analysis results for month n. This represents the purity of the 

soda ash produced.

(Tt)n = Mass of trona input in month n (tons).

(Tsa)n = Mass of soda ash output in month n (tons).

2000/2205 = Conversion factor to convert tons to metric tons.

0.097/1 = Ratio of ton of CO2 emitted for each ton of trona.

0.138/1 = Ratio of ton of CO2 emitted for each ton of soda ash produced.

(3) Site-specific emission factor method. Use Equations CC-3, CC-4, and CC-5 of this 

section to determine annual CO2 process emissions from manufacturing lines that use the liquid 

alkaline feedstock process to produce soda ash. You must conduct an annual performance test 

and measure CO2 emissions and flow rates at all process vents from the mine water 

stripper/evaporator for each manufacturing line and calculate CO2 emissions as described in 

paragraphs (b)(3)(i) through (b)(3)(iv) of this section.

(i) During the performance test, you must measure the process vent flow from each 

process vent during the test and calculate the average rate for the test period in metric tons per 

hour.

(ii) Using the test data, you must calculate the hourly CO2 emission rate using Equation 

CC-3 of this section:
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Where:

ERCO2 = CO2 mass emission rate (metric tons/hour).

CCO2 = Hourly CO2 concentration (percent CO2) as determined by §98.294(c).

10000 = Parts per million per percent

2.59×10−9 = Conversion factor (pounds-mole/dscf/ppm).

44 = Pounds per pound-mole of carbon dioxide.

Q = Stack gas volumetric flow rate per minute (dscfm).

60 = Minutes per hour

4.53 × 10−4 = Conversion factor (metric tons/pound)

(iii) Using the test data, you must calculate a CO2 emission factor for the process using 

Equation CC-4 of this section:

Where:

EFCO2 = CO2 emission factor (metric tons CO2/metric ton of process vent flow from mine 

water stripper/evaporator).

ERCO2 = CO2 mass emission rate (metric tons/hour).

Vt = Process vent flow rate from mine water stripper/evaporator during annual 

performance test (pounds/hour).

4.53 × 10−4 = Conversion factor (metric tons/pound)

(iv) You must calculate annual CO2 process emissions from each manufacturing line 

using Equation CC-5 of this section:
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Where:

Ek = Annual CO2 process emissions for each manufacturing line, k (metric tons).

EFCO2 = CO2 emission factor (metric tons CO2/metric ton of process vent flow from mine 

water stripper/evaporator).

Va = Annual process vent flow rate from mine water stripper/evaporator (thousand 

pounds/hour).

H = Annual operating hours for the each manufacturing line.

0.453 = Conversion factor (metric tons/thousand pounds).

(4) Calculate and report under subpart C of this part (General Stationary Fuel 

Combustion Sources) the combustion CO2, CH4, and N2O emissions in the soda ash 

manufacturing line according to the applicable requirements in subpart C.

§98.294 Monitoring and QA/QC requirements.

Section 98.293 provides three different procedures for emission calculations. The 

appropriate paragraphs (a) through (c) of this section should be used for the procedure chosen.

(a) If you determine your emissions using §98.293(b)(2) (Equation CC-1 of this subpart) 

you must:

(1) Determine the monthly inorganic carbon content of the trona from a weekly 

composite analysis for each soda ash manufacturing line, using a modified version of ASTM 

E359-00 (Reapproved 2005)e1, Standard Test Methods for Analysis of Soda Ash (Sodium 

Carbonate) (incorporated by reference, see §98.7). ASTM E359-00(Reapproved 2005) e1 is 

designed to measure the total alkalinity in soda ash not in trona. The modified method referred to 

above adjusts the regular ASTM method to express the results in terms of trona. Although 
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ASTM E359-00 (Reapproved 2005) e1 uses manual titration, suitable autotitrators may also be 

used for this determination.

(2) Measure the mass of trona input to each soda ash manufacturing line on a monthly

basis using belt scales or methods used for accounting purposes.

(3) Document the procedures used to ensure the accuracy of the monthly measurements 

of trona consumed.

(b) If you calculate CO2 process emissions based on soda ash production (§98.293(b)(2) 

Equation CC-2 of this subpart), you must:

(1) Determine the inorganic carbon content of the soda ash (i.e., soda ash purity) using 

ASTM E359-00 (Reapproved 2005) e1 Standard Test Methods for Analysis of Soda Ash 

(Sodium Carbonate) (incorporated by reference, see §98.7). Although ASTM E359-00 

(Reapproved 2005) e1 uses manual titration, suitable autotitrators may also be used for this 

determination.

(2) Measure the mass of soda ash produced by each soda ash manufacturing line on a 

monthly basis using belt scales, by weighing the soda ash at the truck or rail loadout points of 

your facility, or methods used for accounting purposes.

(3) Document the procedures used to ensure the accuracy of the monthly measurements 

of soda ash produced.

(c) If you calculate CO2 emissions using the site-specific emission factor method in 

§98.293(b)(3), you must:

(1) Conduct an annual performance test that is based on representative performance (i.e., 

performance based on normal operating conditions) of the affected process.

(2) Sample the stack gas and conduct three emissions test runs of 1 hour each.
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(3) Conduct the stack test using EPA Method 3A at 40 CFR part 60, appendix A-2 to 

measure the CO2 concentration, Method 2, 2A, 2C, 2D, or 2F at 40 CFR part 60, appendix A-1 

or Method 26 at 40 CFR part 60, appendix A-2 to determine the stack gas volumetric flow rate. 

All QA/QC procedures specified in the reference test methods and any associated performance 

specifications apply. For each test, the facility must prepare an emission factor determination 

report that must include the items in paragraphs (c)(3)(i) through (c)(3)(iii) of this section.

(i) Analysis of samples, determination of emissions, and raw data.

(ii) All information and data used to derive the emissions factor(s).

(iii) You must determine the average process vent flow rate from the mine water 

stripper/evaporater during each test and document how it was determined.

(4) You must also determine the annual vent flow rate from the mine water 

stripper/evaporater from monthly information using the same plant instruments or procedures 

used for accounting purposes (i.e., volumetric flow meter).

§98.295 Procedures for estimating missing data.

For the emission calculation methodologies in §98.293(b)(2) and (b)(3), a complete 

record of all measured parameters used in the GHG emissions calculations is required (e.g., 

inorganic carbon content values, etc.). Therefore, whenever a quality-assured value of a required 

parameter is unavailable, a substitute data value for the missing parameter shall be used in the 

calculations as specified in the paragraphs (a) through (d) of this section. You must document 

and keep records of the procedures used for all such missing value estimates.

(a) For each missing value of the weekly composite of inorganic carbon content of either 

soda ash or trona, the substitute data value shall be the arithmetic average of the quality-assured 

values of inorganic carbon contents from the week immediately preceding and the week 
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immediately following the missing data incident. If no quality-assured data on inorganic carbon 

contents are available prior to the missing data incident, the substitute data value shall be the first 

quality-assured value for carbon contents obtained after the missing data period.

(b) For each missing value of either the monthly soda ash production or the trona 

consumption, the substitute data value shall be the best available estimate(s) of the parameter(s), 

based on all available process data or data used for accounting purposes.

(c) For each missing value collected during the performance test (hourly CO2

concentration, stack gas volumetric flow rate, or average process vent flow from mine water 

stripper/evaporator during performance test), you must repeat the annual performance test 

following the calculation and monitoring and QA/QC requirements under §§98.293(b)(3) and 

98.294(c).

(d) For each missing value of the monthly process vent flow rate from mine water 

stripper/evaporator, the subsititute data value shall be the best available estimate(s) of the 

parameter(s), based on all available process data or the lesser of the maximum capacity of the 

system or the maximum rate the meter can measure.

§ 98.296 Data reporting requirements.

In addition to the information required by § 98.3(c), each annual report must contain the 

information specified in paragraphs (a) or (b) of this section, as appropriate for each soda ash 

manufacturing facility.

(a) If a CEMS is used to measure CO2 emissions, then you must report under this subpart 

the relevant information required under § 98.36 and the following information in this paragraph 

(a):

(1) Annual consumption of trona or liquid alkaline feedstock at the facility level (tons).
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(2) Annual production of soda ash for each manufacturing line (tons).

(3) Annual production capacity of soda ash for each manufacturing line (tons).

(4) Identification number of each manufacturing line.

(b) If a CEMS is not used to measure CO2 emissions, then you must report the 

information listed in this paragraph (b):

(1) Identification number of each manufacturing line.

(2) Annual process CO2 emissions from each soda ash manufacturing line (metric tons).

(3) Annual production of soda ash for each manufacturing line (tons).

(4) Annual production capacity of soda ash for each manufacturing line (tons).

(5) Annual consumption of trona or liquid alkaline feedstock at the facility level (tons).

(6) Reserved.

(7) Reserved.

(8) Whether CO2 emissions for each manufacturing line were calculated using a trona 

input method as described in Equation CC-1 of this subpart, a soda ash output method as 

described in Equation CC-2 of this subpart, or a site-specific emission factor method as 

described in Equations CC-3 through CC-5 of this subpart.

(9) Number of manufacturing lines located used to produce soda ash.

(10) If you produce soda ash using the liquid alkaline feedstock process and use the sitespecific emission factor method (§ 98.293(b)(3)) to estimate emissions then you must report the 

following relevant information for each manufacturing line or stack:

(i) Stack gas volumetric flow rate during performance test (dscfm).

(ii) Hourly CO2 concentration during performance test (percent CO2).
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(iii) CO2 emission factor (metric tons CO2/metric tons of process vent flow from mine 

water stripper/evaporator).

(iv) CO2 mass emission rate during performance test (metric tons/hour).

(v) Average process vent flow from mine water stripper/evaporator during performance 

test (pounds/hour). 

(vi) Annual process vent flow rate from mine water stripper/evaporator (thousand 

pounds/hour).

(11) Number of times missing data procedures were used and for which parameter as 

specified in this paragraph (b)(11):

(i) Trona or soda ash (number of months).

(ii) Inorganic carbon contents of trona or soda ash (weeks).

(iii) Process vent flow rate from mine water stripper/evaporator (number of months).

§ 98.297 Records that must be retained.

In addition to the records required by § 98.3(g), you must retain the records specified in 

paragraphs (a) through (c) of this section for each soda ash manufacturing line.

(a) If a CEMS is used to measure CO2 emissions, then you must retain under this subpart 

the records required for the Tier 4 Calculation Methodology specified in subpart C of this part 

and the information listed in this paragraph (a):

(1) Monthly production of soda ash (tons)

(2) Monthly consumption of trona or liquid alkaline feedstock (tons)

(3) Annual operating hours (hours).

(b) If a CEMS is not used to measure emissions, then you must retain records for the 

information listed in this paragraph (b):
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(1) Records of all analyses and calculations conducted for determining all reported data 

as listed in § 98.296(b).

(2) If using Equation CC-1 or CC-2 of this subpart, weekly inorganic carbon content 

factor of trona or soda ash, depending on method chosen, as measured by the applicable method 

in § 98.294(b) (percent by weight expressed as a decimal fraction).

(3) Annual operating hours for each manufacturing line used to produce soda ash (hours).

(4) You must document the procedures used to ensure the accuracy of the monthly trona 

consumption or soda ash production measurements including, but not limited to, calibration of 

weighing equipment and other measurement devices. The estimated accuracy of measurements 

made with these devices must also be recorded, and the technical basis for these estimates must 

be provided.

(5) If you produce soda ash using the liquid alkaline feedstock process and use the sitespecific emission factor method to estimate emissions (§ 98.293(b)(3)) then you must also retain 

the following relevant information:

(i) Records of performance test results.

(ii) You must document the procedures used to ensure the accuracy of the annual average 

vent flow measurements including, but not limited to, calibration of flow rate meters and other 

measurement devices. The estimated accuracy of measurements made with these devices must 

also be recorded, and the technical basis for these estimates must be provided.

(c) Verification software records. You must keep a record of the file generated by the 

verification software specified in § 98.5(b) for the applicable data specified in paragraphs (c)(1) 

through (4) of this section. Retention of this file satisfies the recordkeeping requirement for the 

data in paragraphs (c)(1) through (4) of this section
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(1) Inorganic carbon content in trona input, from the carbon analysis results for month 

(percent by weight, expressed as a decimal fraction) (Equation CC-1 of § 98.293).

(2) Mass of trona input in month (tons) (Equation CC-1).

(3) Inorganic carbon content in soda ash output, from the carbon analysis results for 

month (percent by weight, expressed as a decimal fraction) (Equation CC-2 of § 98.293).

(4) Mass of soda ash output in month (tons) (Equation CC-2).

§98.298 Definitions.

All terms used in this subpart have the same meaning given in the Clean Air Act and 

subpart A of this part.