Appendix 1 

Emissions Inventory Support Memorandum 
Steel Pickling 
1

MEMORANDUM 

TO: Anne Pope, EPA 

FROM: Darcy Wilson, ERG 

DATE: July 15, 2010 

SUBJECT: Emissions Data Used in Residual Risk Modeling for Steel Pickling 

The purpose of this memorandum is to provide information on the RTR database used in 

estimating residual risk for the Steel Pickling Maximum Achievable Control Technology 

(MACT) source category. 

BACKGROUND 

Section 112 of the Clean Air Act (CAA) establishes a two-stage regulatory process to 

address emissions of hazardous air pollutants (HAPs) from stationary sources. In the first 

stage, section 112(d) requires the Environmental Protection Agency (EPA) to develop 

technology-based standards for categories of industrial sources. In the second stage, 

known as the residual risk stage, section 112(f)(2) requires EPA to assess the health and 

environmental risks that remain after sources come into compliance with MACT. If 

additional risk reductions are necessary to protect public health with an ample margin of 

safety or to prevent adverse environmental effects, EPA must develop standards to 

address these remaining risks. As part of this second stage, data were gathered to assess 

the residual risks from the Steel Pickling MACT source category. 

EMISSIONS DATA USED IN RESIDUAL RISK MODELING 

The 2005 National Emissions Inventory (NEI) data that were modeled in the EPA’s 

initial 2005 National Air Toxics Assessment (NATA) risk assessment in June of 2009 

served as the starting point for this assessment. Using the process MACT code,1 a subset 

of the NEI was developed that contained facility, process, and emissions data for each 

facility in the Steel Pickling source category (MACT code 0310). 

After initial 2005 NATA modeling, EPA evaluated the 2005 NEI to see if missing Steel 

Pickling facilities could be identified and added to the NEI, if any revisions were needed 

for facilities in the NEI, and if any facilities were identified erroneously as Steel Picking 

facilities, or facilities have closed. To identify additional facilities, EPA reviewed the 

AIST 2009 Directory of Iron and Steel Plants. The AIST directory also helped EPA 

revise MACT code assignments to identify additional facilities as Steel Pickling facilities 

that were already included in the NEI. Facilities that were erroneously identified as 

having Steel Pickling operations were identified based on contacts with facilities to 

 

1

 Assigning data with MACT codes allows EPA to determine reductions attributable to the MACT 

program. The NEI associates MACT codes corresponding to MACT source categories with stationary 

major and area source data. 
2

discuss their operations (e.g., they are not subject to the Steel Pickling NESHAP because 

they don’t do steel pickling).

Emissions data for high-risk facilities identified in the initial NATA modeling were 

reviewed and compared against several years of Toxic Release Inventory (TRI) data 

and State inventory data. Several facilities were contacted to confirm (or correct) 

emission values. In addition to revising emission estimates based on this analysis, the 

following types of revisions were also made to improve the 2005 NEI for Steel Pickling 

facilities: revised Source Classification Codes (SCCs) that provide process information, 

revised emission release point coordinate locations and types (reported as either a stack 

emission source or a fugitive emission source), and revised stack parameters such as the 

height or diameter of the stack. 

EPA also evaluated the facility-wide risks for Steel Pickling facilities using the 2005 NEI 

data and risk assessment results that were released in the 2005 NATA Risk Preview with 

State and local agencies in June of 2010. Emission revisions were made for one facility 

based on the 2005 NATA Risk Preview comments, but not for steel pickling processes at 

the facility. These revisions were not included in the risk analyses, but will be reflected in 

the final NATA risk assessment.