Model Clearinghouse Information Storage and Retrieval System
Record Details

Issue:  EPA Region 3 is seeking concurrence from the Model Clearinghouse 
on a modeling approach using a combination of the Buoyant Line and Point 
Source model (BLP) and American Meteorological Society/Environmental 
Protection Agency Regulatory Model (AERMOD) to represent fugitive emissions 
from coke oven batteries at the U.S. Steel Mon Valley Works - Clairton 
plant located in Allegheny, Pennsylvania. Allegheny County Health 
Department (ACHD) has sought approval under 40 CFR Part 51, Appendix W-
Guideline on Air Quality Models, paragraph 3.2.2(b)(2) to use this 
alternative model in its 2012 Annual Fine Particulate Matter (PM-2.5) 
National Ambient Air Quality Standard (NAAQS) nonattainment area State 
Implementation Plan (SIP) for the Allegheny County, PA nonattainment area 
and the 2010 1-hr SO2 NAAQS nonattainment area SIP for the Allegheny, PA 
nonattainment area submitted to EPA on October 3, 2017. Justification for 
the approval of the alternative model is provided in the ACHD's technical 
support document entitled "Alternative Modeling Technical Support Document: 
BLP/AERMOD Hybrid Approach for Buoyant Fugitives in Complex Terrain." EPA 
Region 3 has performed a technical review of ACHD's submittal and propose 
that the use of the BLP/AERMOD hybrid alternative model should be granted 
in this case.

C/H Response:  The Model Clearinghouse appreciates the efforts by 
EPA Region 3 to thoroughly review the ACHD technical support document and 
summarize their results in its Concurrence Request Memorandum. ACHD is 
seeking to use a combination of the BLP and AERMOD models to represent the 
fugitive emissions from coke oven batteries at the Clairton Plant as 
described in the ACHD technical support document. Specifically, estimates 
of emissions temperature and vertical velocity are used to compute buoyancy 
for input into BLP’s plume rise module to yield estimated plume rise and 
subsequently derive initial vertical dispersion characteristics on an hourly 
varying basis as function of the plume height. The plume rise is then used 
to determine volume source characteristics for the fugitive emissions with 
AERMOD.

For situations where it has been determined that an EPA preferred model 
is either not appropriate for the particular application or a more 
appropriate model or technique is available and applicable, the EPA Regional 
Administrators have the delegated authority to issue an alternative model 
approval under Section 3.2 of the Guideline, provided that such an 
approval is issued after consultation with the Model Clearinghouse. In this 
determination, the Guideline provides guidance to an objective and consistent 
evaluation protocol for the basis of the associated alternative model 
demonstration. The “Protocol for Determining the Best Performing Model” 
(EPA-454/R-92-025, NTIS No. PB 93-226082), also known as the Cox-Tikvart 
Protocol, provides a general framework for objective decision-making on the 
acceptability of an alternative model for a given regulatory application.

We find and agree with the EPA Region 3 assessment that ACHD applied the 
Cox-Tikvart Protocol using a network of facility representative ambient 
monitors and sufficiently demonstrated, per Section 3.2.2(b)(2) of the 
Guideline, that the BLP/AERMOD Hybrid Approach performed better than the 
EPA’s preferred model approach and other approaches tested for characterizing 
the fugitive emissions from the coke oven batteries at the Clairton Plant.

Memo:  Model Clearinghouse Review of the BLP/AERMOD Hybrid Alternative Model 
Approach for Modeling Fugitive Emissions from Coke Oven Batteries at the 
U.S. Steel Mon Valley Works – Clairton Plant in Allegheny County, PA
        Dated: August 10, 2018
        From:  George Bridgers, Model Clearinghouse Director
                 Air Quality Modeling Group, Air Quality Assessment Division, 
                 Office of Air Quality Planning and Standards
        To:    Timothy A. Leon Guerrero, Meteorologist
                 Office of Air Monitoring and Analysis, Air Protection Division, 
                 EPA Region 3
	       Alice Chow, Associate Director
                 Office of Air Monitoring and Analysis, Air Protection Division, 
                 EPA Region 3

Memo:  Concurrence Request for Approval of Alternative Model: BLP/AERMOD Hybrid 
Approach for Modeling Fugitive Emissions from Coke Oven Batteries at the 
U.S. Steel Mon Valley Works - Clairton plant in Allegheny County, PA
        Dated: August 7, 2018
        From:  Timothy A. Leon Guerrero, Meteorologist
                 Office of Air Monitoring and Analysis, Air Protection Division, 
                 EPA Region 3
        Thru:  Alice Chow, Associate Director
                 Office of Air Monitoring and Analysis, Air Protection Division, 
                 EPA Region 3
        To:  George Bridgers, Model Clearinghouse Director
                 Air Quality Modeling Group, Air Quality Assessment Division, 
                 Office of Air Quality Planning and Standards

TSD Attachment:  Alternative Modeling Technical Support Document: BLP/AERMOD Hybrid 
Approach for Buoyant Fugitives in Complex Terrain
        Dated: July 27, 2018
        Submitted To: Environmental Protection Agency, Region 3
        Prepared By: Allegheny County Health Department Air Quality Program