Current NSR+PSD Area Classifications, plus offset calculations

Current Requirements

Source Classif.

Sources subject to NSR PSD

Attainment

 

Non-attain.

 

Maintenance

Minor (< SER)

no requirements for all areas

     

Major

(SER to Federal Major)

BACT or LAER

  

LAER

 

BACT

 

Offsets

  

yes

 

yes *

 

NAQB

  

yes

 

yes *

 

AQ Anal.: Class II/III NAAQS and Increments

    

yes

 

AQ Anal.: Class I NAAQS and Increments

    

yes

 

AQ Anal.: Eval. alternative sites, processes, etc.

  

yes if >100 tpy

  

Federal Major

BACT or LAER

BACT

 

LAER

 

BACT

 

Offsets

yes**

 

yes

 

yes *

 

NAQB

yes**

 

yes

 

yes *

 

AQ Anal.: Class II/III NAAQS and Increments

yes

   

yes

 

AQ Anal.: Class I NAAQS and Increments

yes

   

yes

 

AQ Anal.: Evaluate alternative sites, processes, etc.

  

yes if>100 tpy

  
 

AQ Anal.: Additional Impacts

yes

   

yes

 

AQ Anal.: Class I AQRV Protection

yes

 

yes

 

yes

 

AQ Monitoring

yes

    
 

May also be subject to Attainment PSD requirements

    

yes

       

Source Classif.

Sources not subject to NSR PSD

     

Minor (< SER)

no requirements for all areas

     

Major

(SER to Federal Major)

Offsets

  

yes

 

yes *

 

NAQB

  

yes

 

yes *

 

AQ Anal.: Class II/III NAAQS and Increments

yes

   

yes

 

AQ Anal.: Class I NAAQS and Increments

yes

   

yes

Federal Major

 

Offsets

  

yes

 

yes *

 

NAQB

  

yes

 

yes *

 

AQ Anal.: Class II/III NAAQS and Increments

yes

   

yes

 

AQ Anal.: Class I NAAQS and Increments

yes

   

yes

 

AQ Anal.: Class I AQRV Protection

yes

 

yes

 

yes

 

*  With specified exemptions and alternatives

**  If impacting Nonattainment or Maintenance Areas; or PM10 Maintenance Areas with specified exemptions and alternatives

 

Proposed Requirements

Source Classif.

Major New Source Review

(Sources subject to NSR PSD)

Attainment

Potential NA

Non-attain.

Transitional

Maintenance

Minor (<SER)

no requirements for all areas

     

Minor (SER to 99)

      

Oregon Major (>=100 tpy)

BACT or LAER

  

LAER

 

BACT

 

Offsets

  

yes, 1.2-1.0:1

 

yes *

 

NAQB

  

yes, =offsets

 

yes, = offsets *

 

AQ Anal.: Class II/III NAAQS and Increments

    

yes

 

AQ Anal.: Class I NAAQS and Increments

    

yes

 

AQ Anal.: Eval. alternative sites, processes, etc.

  

yes if >100 tpy

  

Federal Major

BACT or LAER

BACT

BACT

LAER

LAER

BACT

 

Offsets

yes**

yes, ≤1.0:1

yes, ≤1.2:1

yes, ≤1.2:1

yes *

 

NAQB

=offsets**

=offsets

=offsets

=offsets

=offsets *

 

AQ Anal.: Class II/III NAAQS and Increments

yes

yes

 

yes

yes

 

AQ Anal.: Class I NAAQS and Increments

yes

yes

 

yes

yes

 

AQ Anal.: Evaluate alternative sites, processes, etc.

  

yes if>100 tpy

yes if>100 tpy

 
 

AQ Anal.: Additional Impacts

yes

yes

 

yes

yes

 

AQ Anal.: Class I AQRV Protection

yes

yes

yes, vis. only?

yes, vis. only?

yes

 

AQ Monitoring

yes* ???

yes***

 

yes***

 
 

May also be subject to Attainment PSD requirements

    

yes

 

Must not cause a new violation of a NAAQS

 

yes???

   

Source Classif.

Minor New Source Review

(Sources not subject to Major New Source Review)

     

Minor (<SER)

no requirements for all areas

     

Minor (SER to 99)

 

NAAQS,

PSD increments

offsets at 1:1 or less if from priority sources,

NAAQS,

PSD increments

BACT,

offsets at 1:1 or less if from priority sources

BACT,

offsets at 1:1 or less if from priority sources,

NAAQS,

PSD increments

BACT,

offsets at 1:1 or less if from priority sources,

NAAQS,

PSD increments

Major >=100 tpy

Offsets

 

yes, ≤1.0:1

yes, ≤1.0:1

yes *

yes *

 

NAQB

  

=offsets

=offsets *

=offsets *

 

AQ Anal.: Class II/III NAAQS and Increments

yes

yes

 

yes

yes

 

AQ Anal.: Class I NAAQS and Increments

???

???

 

???

???

Federal Major

 

Offsets

 

yes, ≤1.0:1

yes, ≤1.0:1

 

yes *

 

NAQB

  

=offsets

 

=offsets *

 

AQ Anal.: Class II/III NAAQS and Increments

yes

yes

  

yes

 

AQ Anal.: Class I NAAQS and Increments

???

???

  

???

 

AQ Anal.: Class I AQRV Protection

yes

yes

yes

yes

yes

 

*  With specified exemptions and alternatives

**  If impacting Nonattainment or Maintenance Areas; or PM10 Maintenance Areas with specified exemptions and alternatives

***  No exemptions or alternatives

 

 

Offset concept for encouraging sources to get offsets from “priority” sources (e.g. woodstoves) in a non-attainment area.

 

NOTE: change name from “problem” sources to “priority” sources ?

 

The offset ratio varies depending on the offsets from the priority sources. Over the range of offsets from the priority sources from 0 to 10 percent, the offset ration varies linearly, with the minimum offset ratio of 1.0 to 1 when 10 percent of the source’s emissions are offset by priority source emissions. The maximum offset ratio is 1.2 to 1 when 0 percent of the source’s emissions are offset by priority source emissions. Over the range of offsets from the priority sources from 10 to 100 percent, the offset ratio is constant at 1.0 to 1.

 

DEQ has taken this approach because we recognize that while obtaining offsets from the priority sources in an area is most desirable, it is also likely to be more difficult than obtaining offsets from industrial sources. Thus, although there is no incentive to obtain more than 10 percent of the offsets from the priority sources, there is a significant incentive to obtain at least some of the offsets from the priority sources.

 

Terms

Procedure

E = new or modified source emissions which must be offset, tons per year

R = offset ratio

T = total offsets required, tons per year

P = offsets from priority sources, tons per year

I = offsets from industrial sources, tons per year

 

T = E*R = P + I

 

F = percentage of E from priority sources = P/E*100

•  When F is 0 percent, R = 1.20

•  When F is 5 percent, R = 1.10

•  When F is ≥10 percent, R = 1.00

 

1.  For a specific situation, E will be known.

 

2.  Determine offsets P from the priority sources:

•  P = tons per year of offsets from priority sources

•  P is rounded to the nearest whole ton.

 

3.  Calculate F:

•  F = P/E*100

•  F is rounded to nearest whole percent.

 

4.  Determine R:

•  R = 1.20 - 0.02*F (with F expressed as a percentage) over the range of F from 0 to 10 percent.

◦  R must be rounded off to 2 decimal places; if the result is < 1.00, then R = 1.00.

•  R = 1.00 over the range of F from 10 to 100 percent.

 

5.  Determine total offsets required:

•  T = E*R

•  T is rounded to the nearest whole ton.

 

6.  Determine industrial offsets required:

•  I = T - P

 

 

 

 

 

 

 

 

Note:

There is a possible different approach for F, but it’s much more difficult to use. In this other approach, the percent (or fraction) F is the fraction of the total offsets required (i.e. E*R), not the fraction of the emissions that must be offset (E) as above. This approach is more difficult because as the offset ratio varies, the total number of offsets also varies, but the offset ratio is a function of the total number of offsets. In other words, the offset ratio R is a function of itself and the math becomes rather cumbersome. After playing around with it for a day, I went with the simpler approach above.

 

E = source emissions subject to offset requirements

R= offset ratio

T = total offsets required = E*R

P = offsets from priority sources (eg. woodstoves)

I = offsets from industrial sources

 

T = E*R = P + I

 

F = fraction of total offsets from priority sources = P/(P+I) or F = P/T and P = F*T