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  • Writer's pictureTom Petersen

Air Regulation Changes - Do They Affect Your Facility?

Updated: Aug 28, 2023

On May 19, 2007, the revised air quality Nonattainment New Source Review (NNSR) regulations were published in Pennsylvania. These revisions were made as a result of EPA’s 2002 amendments to the federal Prevention of Significant Deterioration (PSD) and NNSR regulations.

For those of you who have worked with these air regulations in the past, you should find that the revisions are less nebulous than what was on the books. With the addition of a large number of definitions and clarifying language, the regulations are easier to understand. In addition, the revision brings Pennsylvania into closer alignment with federal regulations, with several key differences. Today’s article outlines the basics of this regulation as well as provides highlights of the recent changes and the differences from the Federal regulations.

New Source Review reform in New Jersey and Delaware remains in a state of flux. We will cover changes in these states in subsequent posts.

NNSR Basics

For those of you new to air permitting, the NNSR regulations and with its myriad of definitions might seem a bit overwhelming. Here are the basics (words in bold have a specific definition in the regulations):

Locations Subject: Facilities in nonattainment areas for a regulated NSR pollutant (currently CO, NOx, VOC, Ozone, PM-10, SOx, & lead) are potentially subject to this regulation. These areas are defined for Pennsylvania at 40 CFR ß81.339. In addition, the entire state is considered a transport region for Ozone and, therefore, has lower major-source applicability thresholds for ozone precursors (VOC and NOx).

Emissions Calculation: When a new facility is being built or a modification is being made to a facility, its emissions of regulated NSR pollutants must be evaluated to determine what permitting requirements apply. For new facilities, the key emission calculation to perform is the potential to emit. For existing facilities, the terms emission increase, net emission increase, projected actual, baseline actual and significant are critical definitions.

Applicability Evaluation: These emission calculations are compared against threshold limits to determine if they are significant. You are subject to NNSR by being either a new major facility or a major modification at an existing major facility. Applicability varies depending on your location and the pollutant(s) in question. For example, a facility is major for VOC in the Philadelphia region if it has the potential to emit 25 tpy, but not in central Pennsylvania if its PTE is less than 50 tpy.

Subject Facilities: Where both the emission increase and net emission increase is significant, the facility must meet the lowest achievable emission rate (LAER), purchase emission reduction credits (ERCs) to offset the increase, and meet several other requirements. If only the net emission increase is significant, then ERC’s must be purchased to offset the increase.

Plantwide Applicability Limit (PAL): Obtaining this type of limit can be helpful in that it allows you the flexibility to reduce emissions in one part of your facility in order to increase emissions elsewhere without having to go through an extensive permitting process.

Changes in the Regulation

Numerous changes were made to the regulation. Below are some of the highlights.

Definitions: Numerous definitions were changed and several were added.

Extension: Allow extension of 18 month period for construction, modification or installation, provided you demonstrate that extension is justified.

Increase Determinations: Previously based on increase in Potential to Emit. Now based on difference between projected actual and baseline actual for modifications of existing equipment.

Netting Determination: When determining a net emission increase to determine if ERCs must be purchased, the regulation requires a 10 year aggregation period instead of 15 years.

ERC Deadline: The deadline for registering ERCs can be extended from 1 to 2 years if the facility submits a maintenance plan or a request to preserve the emissions in the inventory.

Section 127.211 & 214: These sections were deleted. Applicability determinations are now in 127.203a.

Variations from Federal Regulations

PA DEP made a determination that the federal NNSR regulations are not stringent enough. There are several key differences between the two regulations:

Baseline Emission Calculations: EPA allows you to use emissions from the last 10 years to define the 24 month period. PA DEP only allows 5 unless written approval is obtained.

BAT under PAL: EPA does not require best available technology (BAT) for facilities making a modification under a plant-wide applicability limit (PAL). PA DEP does.

Permit Limits: Projected actual emission estimates established in the NNSR permitting process will be incorporated into operating permit limits. EPA requires a 5 year comparison of projected to actual.

Philadelphia Area Counties: PA DEP requires that facilities in these counties be considered major if their PTE is at least 25 tpy of VOC or NOx. EPA regulations would be less stringent.

Should your facility be contemplating a process or combustion modification and you are finding it a challenge to evaluate the facility against the NNSR or other air quality regulations, EES has extensive experience in New Source Review and other air permitting. We are available to address questions or to work with you on the entire permitting process.

Number 43 part 1



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