December 2018
MEMORANDUM
TO:		Docket ID: EPA-HQ-OAR-2018-0417
FROM:	Nathan Topham, Environmental Engineer, U.S. EPA
SUBJECT:	HCl RTR Modeling File Data Source Documentation
                                 													
1. Data Sources Used to Generate List of Facilities and Emissions Data to be Modeled
	The list of facilities subject to the NESHAP was created through searching the EPA's ECHO database, the 2014 National Emissions Inventory (NEI), and state databases of title V permits. Further discussion of the facility list can be found in "Industry Characterization for the Hydrochloric Acid Production NESHAP Residual Risk and Technology Review," available in docket ID: EPA-HQ-OAR-2018-0417. Once the facility list was finalized, available emissions data were pulled from the NEI. Title V permits were used to determine which emission points at each facility are subject to the HCl NESHAP. These emission points were matched to entries in the NEI. Some NEI entries did not include unit or process descriptions that allowed for matching with units identified in title V permits. As described in section 2 below, emission estimates were used to fill in gaps present in the NEI data for sources listed as subject to the NESHAP in title V permits. 
2. Process Used to Develop Emissions Estimates for Gap Filling
      The NEI was examined to separate any emission points subject to the HCl NESHAP from other emission points at the facilities identified in "Industry Characterization for the Hydrochloric Acid Production NESHAP Residual Risk and Technology Review." Once identified, emission points subject to the NESHAP were categorized based on emission point type (process vent, storage tanks, material transfer and loading, and equipment leaks). The categorized data were used to calculate average values for the following emission point parameters: HCl emissions, Cl2 emissions, stack height, stack diameter, stack velocity, stack temperature, stack flow rate, and fugitive height. The data used to calculate these averages are available in a Microsoft Excel spreadsheet that has been placed in the docket for this proposal. Table 1 presents the average values used for gap filling. 
      Table 1 Average Emission Point Characteristics Used for Gap Filling

HCl Emissions (tpy)
Cl2 Emissions (tpy)
Stack Height (ft)
Stack Temperature (°F)
Stack Diameter (ft)
Stack Velocity (ft/sec)
Stack Flow Rate (ft[3]/sec)
Uncategorized Data
0.114

0.079

81.461

81.289

1.461

45.996

77.127

Process Vents
0.515

0.659

85.762

180.955

1.355

16.609

23.936

Material Transfer and Loading
0.031
N/A
20.286

87.286

0.564

33.407

8.355

Storage Tanks
0.297

N/A

18

81.571

0.486

1.45

0.269

Equipment Leaks
1.146

N/A






	We compared the NEI data to title V permits to determine whether the NEI included all emission points listed as subject to the NESHAP according to the permit. When gaps in the NEI data were identified, the average values calculated for missing emission point parameters were used to fill gaps. 
	We evaluated latitudes and longitudes listed in the NEI to ensure their accuracy. For some emission points, we determined that slight corrections were necessary (for example, if a latitude/longitude for a tank was located near the tank but not on it). In these cases, we used our best judgment based on the type of emission point and proximity of other emission points related to HCl production to refine the latitude/longitude estimates. All of the latitudes and longitudes used in our dispersion modeling are in the modeling file used for the proposed rule, which is available in docket ID: EPA-HQ-OAR-2018-0417.	
3. Wastewater, Acute emissions, and Allowable Emissions
      Wastewater emissions were estimated for two facilities. These two facilities were Arkema Inc. in Calvert City, KY and Honeywell in Geismar, LA. These two facilities were chosen because they represented the highest overall HCl emissions (Arkema Inc.) and the facility with the highest chronic inhalation risk results for the source category, excluding wastewater (Honeywell Inc.). The only wastewater emissions data available were from the original NESHAP support documents. At that time, based on the limited data available to the Agency, we estimated that wastewater emissions comprised roughly 0.5% of the total source category emissions. For the residual risk review, we assumed that wastewater emissions comprise roughly 1% of total source category emissions at each of the two facilities modeled.
As discussed in Section III of the preamble to the proposed rule, we used a factor of 10 times actual emissions to estimate short-term emissions from process vents, HCl storage tanks, HCl transfer operations, and equipment leaks for the acute assessment. We used a factor of 10 times actual emissions for allowable emissions estimates from process vents, HCl storage tanks, and HCl transfer operations while the allowable emission rates for equipment leaks were set equal to actual emission rates. We estimated facility-wide emission rates using data pulled from the 2014 NEI.
4. Uncertainties in Emissions Estimates
	We recognize that there are uncertainties associated with the emissions estimates developed for this proposed rule. Some possible areas of uncertainty include the following:
 Accuracy of the emission point parameters entered into the NEI.
 Possible overestimation of source category emissions if emissions subject to the HCl Production NESHAP are combined with non-category emissions in NEI entries.
 Uncertainty associated with estimating facility boundaries using satellite imagery.  
      While these uncertainties may have a small effect on dispersion modeling results, we expect that it would likely bias the results towards a more conservative estimate of risk. We included a review tool to allow stakeholders to provide corrections to the parameters used in our dispersion modeling to support the proposed rule in docket ID: EPA-HQ-OAR-2018-0417.
5. Facility-Specific Emissions Estimate Adjustments
Evonik  -  Theodore, Al
	Data from NEI appear to include all sources listed in the facility's title V permit as subject to the NESHAP. NEI data do not include information about specific source type (process vent, tank, etc.). No changes were made to the NEI data.
BASF  -  Macintosh, Al
	The NEI includes one entry for the unit listed in the facility's title V permit as subject to the NESHAP. There are HCl emissions associated with this emission point but no chlorine emissions. The emission point in the NEI appears to correspond to emission point: IG-EP-01A (Caustic Scrubber) from the facility's title V permit. There is a single 10,000 gallon HCl storage tank listed in the title V permit (emission point: 771-V-07). This tank is controlled via the caustic scrubber mentioned above. There was no entry in the NEI for material transfer and loading or equipment leaks. These two sources were added based on the emissions estimates described above in section 2.
Dow  -  Pittsburg, CA
	The HCl and Cl2 emissions for this facility in the NEI appear to be pulled from the TRI. There are entries for HCl and Cl2 for stacks and fugitives. The estimates included in the NEI may be conservative since it is unclear that they are limited to sources subject to the HCl Production NESHAP. The facility provided updates to the NEI data. The TRI emissions were apportioned to individual emission points at the facility. In two instances, the stack parameters provided by the facility yielded stack velocities that were abnormally high (i.e. over 2000 feet/second). In these two cases, we assumed the facility had provided stack flow rates in cubic feet per minute rather than cubic feet per second and converted the calculated velocity into feet per second. This conversion resulted in values that were more in line with other sources at the facility. 
BASF  -  Kankakee, IL
	According to the facility's title V permit, "Area 90, CSA Process" is subject to the NESHAP. There is no NEI entry with this description. Therefore, emissions estimates described in section 2 were used for process vents, tanks, material transfer and loading, and leaks. 
Arkema  -  Calvert City, KY
	The NEI data include emissions estimates for all sources subject to emission standards in the HCl Production NESHAP. No changes to the NEI data were made. Missing stack velocity for emission point 4000 was calculated from stack diameter and flow rate found in the NEI data.
Chemours  -  Louisville, KY
	The NEI data appear to include HCl emissions for all sources subject to the HCl Production NESHAP. However, none of these sources had Cl2 emissions included in the NEI data. Therefore, we added Cl2 emissions for process vents using the emissions estimates described in section 2.
Honeywell  -  Geismar, LA
	The NEI data appear to include HCl and Cl2 emissions for all emission units subject to the NESHAP. No changes were made to the NEI data. 
Rubicon  -  Geismar, LA
	Some emission points were found in the NEI. However, a number of emission points of all types were not matched. Emission factors were used to add emissions from process vents, tanks, material transfer and loading, and equipment leaks. Missing stack flow rate for emission point "MDI Fume Scrubber AS-4303 was calculated using stack diameter and velocity from the NEI data.
BASF  -  Geismar, LA
	Some emission points were found in the NEI. However, a process vent and tank emission points were not matched. Emission factors were used to add emissions from process vents and tanks. 
Honeywell  -  Baton Rouge LA
	The NEI appears to include HCl and Cl2 emissions for all emission units subject to the NESHAP. No changes were made to the NEI data. 
Dow  -  Plaquemine LA
	The NEI data appear to include HCl and Cl2 emissions for all emission units subject to the NESHAP except for one emission point. There are no HCl or Cl2 emissions for EQT1303  -  CE-Scrubber C-501. Emission factors were used to add emissions of HCl and Cl2 from this process vent.
Hexion  -  Norco LA
	The NEI data appear to include HCl emissions for all emission units subject to the NESHAP except for tanks. There are no HCl data for tanks and no Cl2 data for process vents.
Dow  -  Midland MI
	The NEI data appear to include HCl data for all emission units subject to the NESHAP. However, there are no Cl2 emissions in the NEI data for the emission points subject to the NESHAP. Emission factors were used to add emissions of Cl2 from process vents.
Polymer Additives  -  Bridgeport NJ
	The NEI data do not include unit descriptions that allow for matching with any emission units listed in the facility's title V permit as subject to the HCl NESHAP. Only one entry for HCl and Cl2 were found in the NEI data and these entries did not include unit descriptions or stack parameters. Emission factors were used to add emissions of HCl and Cl2 from process vents and HCl emissions from storage tanks, material transfer and loading, and equipment leaks. 
Momentive Performance Materials  -  Waterford NY
      The NEI data do not include unit descriptions that allow for matching with any emission units listed in the facility's title V permit as subject to the HCl NESHAP. Emission factors were used to add emissions of from process vents, storage tanks, material transfer and loading, and equipment leaks.
Chemours  -  Washington WV
	The NEI data do not include unit descriptions that allow for matching with any emission units listed in the facility's title V permit as subject to the HCl Production NESHAP. Emission factors were used to add emissions from process vents, storage tanks, material transfer and loading, and equipment leaks. 
Dow  -  Freeport TX
	Some emission points were found in the NEI. However, a process vent was not matched. Emission factors were used to add emissions from process vents. 
Cabot Corporation  -  Tuscola IL
	Some emission points were found in the NEI. However, a process vent and equipment leaks were not matched. Emission factors were used to add emissions from process vents and equipment leaks. 
PPG South  -  Barberton OH
      The HCl and Cl2 emissions for this facility in the NEI appear to be pulled from the TRI. There are entries for HCl and Cl2 for stacks and fugitives. The estimates included in the NEI may be conservative since it is unclear that they are limited to sources subject to the HCl Production NESHAP. No changes to the NEI data were made.	


