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OAR Box 1778 

Prepped by Ollie Stewart 

Document Number: 

19) ll-A-3 

Docket Number: 

A-90-06 

Printed 10/28/2008 9:50:52 AM Sheet 19 of 276 
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SUBJECT: 

FROM: 

TO: 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

Office of Air Quality Planning and Standards 

Research Triangle Park, North Carolina 27711 

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II-A-3 

Prevention of Significant Deterioration (PSD) Program StatisticsGary McCutchen, Chief 

New Source Review Section (MDNancy Kete (ANR-443) 

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The Clean Air Act applies PSD requirements to new^sojjjices-terfger 

either 100 tons per year (tpy) [f°r certain source categories, such as iron 

and steel mills and power plants] or 250 tpy [for all other sources] and to 

major modifications [physical or operational changes to an existing major 

source which result in a significant net emissions increase]. The PSD rules 

allow sources proposing to modify an emissions unit to avoid review provided 

the change: 

is not considered a physical change or change in the method of 

operation of the source according to EPA's list of exclusions from 

the PSD definition of major modification (e.g., routine repair, 

replacement, and maintenance); or . . 

is minor (i.e., the net emissions increase at the source falls below 

significant emissions levels - such levels vary from 0.0004 tpy for 

beryllium to 100 tpy for CO). 

New source review (NSR) also applies to major new sources (greater than 100 

tpy) and major modifications in designated nonattainment areas. 

There are between 20,000 and 40,000 air pollution permits issued each 

year by State and local agencies and EPA. These include both construction and 

operating permits. Of these, about 1 percent, or 200 to 400, are for major 

sources or major modifications (referred to collectively as "major source 

permits"). The remaining permits are: 

Net-outs - minor sources which would have been major but netted out 

[used emission decreases to cancel out emission increases] of 

review; 

Synthetic minors - sources which would have been major but accepted 

Federally-enforceable restrictions on their emissions limits, 

operating rate, or hours of operation so that the source would 

operate as a minor source; 

Minor new sources - designated to operate at less than either the 

100 or 250 tpy threshold; 
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Minor modifications - less than the "significant net emissions 

increase" threshold for a major modification at a major source and 

any increase less than a major source (100 or 250 tpy) at a minor 

source; and 

Renewals - some agencies require renewal of operating permits 

periodically (typically every 5 years). 

The first two types of non-major permits, net-outs and synthetic minors, 

are alternatives to NSR allowed by EPA regulations. Each year, some 600 

sources elect one of these alternatives, twice the number of sources which go 

through NSR. In fact, recent data fronuthe Regions indicate that the number 

of synthetic minors is actually much larger; the total number of synthetic 

minors reported by only three Regions for 1989 was more than 600. 

The 200-400 major source permits, from EPA audit data, are approximately 

two-thirds PSD and one-third nonattainment NSR sources. Therefore, of the 

average 300 major source permits per year, 200 will be PSD permits. In 

addition, approximately two-thirds of the major source permits are major 

modifications and one-third are new sources. Therefore, approximately 135 of 

the 200 PSD permits are major modifications. It is this population that is 

potentially affected by the WEPCO decision. 

Based on EPA and State experience, the following observations can be 

made. First, tens of thousands of routine repair, replacement, and 

maintenance actions are conducted each day; these are not required to obtain 

any permits at all. Second, typically fewer than two percent of all the 

permits issued qualify as major modifications. Third, of these, only onethird (1/2 of 1 percent of the total of all permits issued) are subject to 

NSR; the remainder select an alternative to NSR. This amounts to only an 

approximate 135 PSD major modification permits per year. Finally, considering 

the large number of permits granted each year, this is a very small 

percentage. Considering that the current PSD rules have been in place for 

nearly 10 years, the number of sources impacted by the actual-to-potential 

comparison has been remarkably small. Of course, the portions of emissions 

affected is much greater because PSD concentrates on the largest sources; PSD 

applies to an estimated 30 to 90 percent of all new emissions. Therefore, 

although the PSD program applies to a large portion of new emissions, it 

affects only a small number of sources, each of which it is important to 

review. 
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PSD/NEW SOURCE REVIEW PERMIT STATISTICS 

For a Typical Year 

20,000-40,000 Air Pollution 

Source Permits (Operating and 

Construction) Issued per Year 

(30,000 average) 

900 (3 percent of total) 

Potentially Major 300 are New Sources 

600 (2 percent of total) 

are Modifications 

400 of these Net-out or 

Take Restrictions to be 

Non-Major 

200 (2/3 of 1 percent of total) 

are Major Modifications 

65 are Nonattainment 

NSR Major Modifications 

135 (1/2 of 1 percent of total) 

are PSD Major Modifications