UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION III

 1650 Arch Street

 Philadelphia, Pennsylvania 19103-2029

DATE: January 5, 2011

SUBJECT: Technical Support Document

Approval of Pennsylvania State Implementation Plan (SIP) Revisions

to Allegheny County Health Department Regulations incorporating Modeling 

Requirements for Major Sources Locating In or Impacting A Nonattainment Area 

FROM: Paul T. Wentworth, P.E.

Office of Permits and Air Toxics (3AP10)

TO: Kathleen Cox, Chief

 Office of Permits and Air Toxics (3AP10)

TECHNICAL SUPPORT DOCUMENT

EPA-R03-OAR-2009-0881

APPROVAL

REVISIONS TO ALLEGHENY COUNTY RULES AND REGULATIONS FOR MAJOR 

SOURCES LOCATING IN OR IMPACTING A NONATTAINMENT AREA 

I. BACKGROUND

On November 16, 2006, The Pennsylvania Department of Environmental Protection 

(PADEP) submitted a revision to Allegheny County’s portion of the Pennsylvania State 

Implementation Plan (SIP) consisting of changes to Allegheny County's Article XXI Air 

Pollution Control Rules and Regulations. The revision incorporates requirements of 40 CFR 

51.160(f), “Modeling Requirements” into new subsection 2102.06(g), “Requirements for 

Modeling” under Section 2102.06, “Major Sources Locating in or Impacting a Non-attainment 

Area”.

40 CFR Part 51 Subpart I, “Review of New Sources and Modifications” requires that 

each SIP contain legally enforceable procedures that enable the State or local agency to 

determine whether the construction or modification of a facility, building or structure or
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installation, or combination of these will result in a violation of applicable portions of the control 

strategy; or interference with attainment or maintenance of a national standard in the state in 

which the proposed source (or modification) is located or in a neighboring State. 40 CFR 

51.160(f) states that these procedures must discuss the air quality data and the dispersion or other 

air quality modeling used to meet the requirements of this subpart. It further stipulates that all 

applications of air quality modeling involved in this subpart shall be based on the applicable 

models, data bases, and other requirements specified in appendix W of this part, Federal 

Guideline on Air Quality Models (Guideline). The Guideline provides model users with a 

common basis for estimating pollution concentrations, assessing control strategies and specifying 

emission limits. The modeling requirements under 40 CFR 51.160 (f)(2) specify that where an 

air quality model specified in appendix W of this part is inappropriate, the model may be 

modified or another model substituted on a case-by-case basis or, where appropriate, on a 

generic basis for a specific State program provided that written approval is obtained from the 

Administrator. Use of a modified or substituted model must be subject to notice and opportunity

for public comment under procedures set forth in 40 CFR 51.102. The modeling requirements of 

40 CFR 51.160 (f)(2) must be incorporated as a new Subsection, 2102.06(g), under Allegheny

County’s Regulation to make Allegheny’s regulation 2102.06 consistent with 40 CFR 51 Subpart 

I.

II. SUMMARY OF ACTION

EPA is approving, via direct final rulemaking action, amendments to Allegheny County’s 

Regulations, section 2102.06 entitled “Requirements for Modeling”, submitted on November 16, 

2006. These amendments consist of a new subsection, 2102.06(g), ‘‘Major Sources Locating in 

or Impacting a Nonattainment Area’’. PADEP is incorporating these amendments into the 

Pennsylvania SIP. This approval action will revise the previously approved versions of these 

rules approved on November 14, 2002 (67 FR 38935) into the Pennsylvania SIP.

III. PROGRAM REVIEW

This section outlines the changes the State of Pennsylvania has made to the existing SIP 

for the purposes of updating their regulations so that they are consistent with the Federal rules as

of the CFR edition dated July 1, 2008. There were no public comments made regarding the 

proposed adoption of the changes to Article XXI Section 2102.06 at the public hearing held on 

January 7, 2005.

Section 2102.06, “Major Sources Locating in or Impacting a Nonattainment Area

Section Status Description

Regulation

2102.06

Added Subsection 

2102.06(g) to 

Regulation

Updated ACHD Regulation to include modeling 

requirements to be consistent with Federal Requirements

In 40 CFR 51 Subpart I
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IV. CONCLUSION

EPA concludes that the result of this SIP revision enables Allegheny County’s program 

to meet all of the program element requirements contained in 40 CFR 51 Subpart I.

V. RECOMMENDED AGENCY ACTION

I recommend that the amended Allegheny County regulation 2102.06 be approved as 

revisions to strengthen the current Pennsylvania State Implementation Plan.