UNITED STATES ENVIRONMENTA L PROTECTION A GENCY REGION III 1650 A rch Street Philadelphia, Pennsy lv ania 19103 - 2029
DATE: January

5, 2011 SUB JECT: Technical Support Document

Approval of Penns yl vania State Implementation Plan (SI P) Revisions to Alleghen y Count y 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 ALL EGHENY COUNTY RULES A ND REGULAT IONS FOR MAJOR SOURCES LOCATING IN OR IMPACTING A NONATTAINMENT AREA

I. BACKGROUND On November 16, 2006, The Pennsy lvania Department of Environmental Protection (PADEP) submitted a revision to Alleghen y County ’s portion of the Pennsylvania State I mplementation Plan (SIP) consisting of changes to Alleghen y Count y's Article XXI Air Pollution Control Rules and Regulations. The revision incorporates requirements of 40 CFR 51.160 (f) , “Modeling Requirements” into new s ubsection 2102.06(g), “Requirements for Modeling” under Section 2102.06, “Major Sources L ocating 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 whe ther the construction or modification of a fa cility , building or structure or2

installation, or combination of these will result in a violation of applicable portions of the control strategy ; or interference with attainment o r maintenance of a nati onal 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. Itfurther stipulates that all applications of air quality modeling involved in this subpart shall be based on the applicable models, data bases, and other requirements speci fied in appendix W of thi s part, Federal Guid eline on Air Qualit y 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 C FR 51 .160 (f)(2) specify that where an air quality

model specifi ed 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 pr ogram provided that written approval is obtained from the Administrator. U se 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. T he 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 Alleghen y’s regulation 2102.06 consistent with 40 CFR 51 Subpart I. II. SUMMARY OF ACTION EPA is approving, via direct final rulemaking actio n, amendments to Allegheny Count y’s Regulations, s ection 2102.06 entitled “Requirements for Modeling ”, submitted on November 16, 2006 . These amendments consist of a new s ubsection, 2102.06 (g), ‘‘Major Sources Locating in or Impacting a Nonattainment Area ’ ’. PADEP is incorporating these amendments into the Pennsy lvania SIP. This approval action will revise the previously approved versions of these rules approved on November 14, 2002 (67 FR 38935) into the Pennsylvania SI P
. III. PROGRAM REVIEW This s ect ion outlines the changes the State of Pennsylvania has made to the existing SI P 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 Add ed Subsection

2102.06(g) to Regulation Updated ACHD Regulation to include modeling

requirements to be consistent with Federal Requirements In 40 CFR 51 Subpart I3

IV. CONCLUSION EPA concludes that the result of this SI P revision enables Alleghen y 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 Alleghen y Count y regulation 2102.06 be approved as revisions to strengthen the current Penns yl van ia State Implementation Plan

.