MOJAQMD RULE 1304 EMISSIONS CALCULATIONS

LAST REVISED 03/25/96

RULE 1304 

EMISSIONS CALCULATIONS

(Adopted: 07/21/80; Amended: 10/27/93; Amended: 03/25/96)

(A) General 

1. Purpose 

(a) This rule provides the procedures and formulas to calculate emissions increases and decreases 

for new or modified Facilities. The results of such calculations shall be used to:

(i) Determine the applicability of the provisions of District Rule 1303. 

(ii) Calculate SERs generated within the same Facility to reduce Proposed Emissions. 

(iii) Determine the Potential to Emit for new or modified Facilities and Emissions Unit(s). 

(B) Calculating Emissions Changes in a Facility 

1. General Emissions Calculations 

(a) The emissions change for a new or modified Facility or Emissions Unit(s) shall be calculated, 

in pounds per day, by subtracting Historic Potential Emissions from Proposed Emissions. 

Emissions Change = (Proposed Emissions) - (Historic Potential Emissions) 

(C) Calculating Simultaneous Emissions Reductions.

1. SERs may result from the Modification or shut down of Existing Emission Unit(s) so long as the 

resulting reductions are Federally Enforceable and are: 

(a) Reductions in Actual Emissions of the Emissions Unit(s); or 

(b) Reductions in the Potential to Emit of an Emissions Unit so long as the Potential to Emit for 

that Emissions Unit was completely offset in a prior permitting action pursuant to this regulation. 

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2. SERs resulting from the Modification or shut down of existing Emission Unit(s) within the same 

Facility shall be calculated as follows: 

(a) For the shutdown of Emissions Unit; 

SER = Historic Actual Emissions 

(b) For Modifications of Emission Unit(s), consisting solely of application of control equipment or 

implementation of a more efficient process; 

SER = (Historic Actual Emissions) x (Control Efficiency) 

(c) For other modifications or limitations on operations of an Emissions Unit(s); 

SER = (Historic Actual Emissions) - (Proposed Emissions) 

3. SERs calculated pursuant to subsection (C)(2) above shall thereafter be adjusted to reflect 

emissions reductions which are otherwise required by Federal, State or District law, rule, order, 

permit or regulation as follows: 

(a) SERs shall be adjusted to reflect only the excess reductions beyond those already achieved by, 

or achievable by, the Emissions Unit using RACT. 

(b) SERs shall be adjusted to reflect only the excess reductions beyond those required by 

applicable District Rules and Regulations. 

(c) SERs shall be adjusted to reflect only the excess reductions beyond those required by any 

applicable proposed District Rules and Regulations which have been taken to public workshop. 

(d) SERs shall be adjusted to reflect the excess reductions beyond those required by any control 

measures identified in the District's Air Quality Attainment Plan or contained in the State 

Implementation Plan of the District and which have not yet been implemented in the form of 

District Rules and/or Regulations. 

4. Positive values as calculated above may only be used to reduce Proposed Emissions as calculated 

pursuant to section (D)(1), for purposes of determining applicability of District Rule 1303(B). 

5. Prior to use, SERs must be approved by the APCO. 

(D) Calculation of Terms Used in Rule 1304 

1. Proposed Emissions 

(a) For a new Facility or Emissions Unit(s), the Proposed Emissions shall be equal to the Potential 

to Emit for that Facility or Emissions Unit as defined by District Rule 1301(VV) and as calculated 

pursuant to subsection (D)(4) below. 

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(b) For a modified Facility or Emissions Unit(s) the Proposed Emissions shall be equal to the 

Potential to Emit after modifictaion for that Facility or Emissions Unit as defined in District Rule 

1301(UU) and as calculated pursuant to subsection (D)(4) below. 

2. Historic Actual Emissions (HAE) 

(a) HAE equal the Actual Emissions of an Emissions Unit or combination of Emissions Units, 

including Fugitive Emissions directly related to those Emissions Unit(s), calculated in pounds per 

year, as follows: 

(i) The verified Actual Emissions of an Emissions Unit, or combination of Emissions Units, 

averaged from the two year period which immediately proceeds the date of application and 

which is representative of Facility operations; or 

(ii) The verified Actual Emissions of an Emissions Unit, or combination of Emissions 

Units, averaged for any two years of the five year period which immediately precedes the 

date of application which the APCO has determined is more representative of Facility 

operations than subsection (1) above. 

(iii) If an Emissions Unit has been in operation for less than one year, the HAE shall be 

equal to zero. 

3. Historic Potential Emissions (HPE) 

(a) HPE equal the Potential to Emit of an existing Emissions Unit or combination of Emissions 

Units prior to Modification, calculated in pounds per year, as follows: 

(i) Any Daily Emissions Limitation for an Emissions Unit or combination of Emissions 

Units shall be treated as a part of the operational design of the Emissions Unit(s) if: 

a. The limitations are representative of Normal Operations; or 

b. The Facility has already provided offsets for such emissions in previous permitting 

actions; and 

c. The emissions limitation is Federally Enforceable. 

(ii) If there are no Federally Enforceable emissions limitations on the Emissions Unit or 

combination of Emissions Units the HAE shall be treated as the Potential to Emit for the 

Emissions Unit(s). 

(iii) The HPE for a new Emissions Unit shall be equal to zero. 

4. Potential To Emit 

(a) The Potential to Emit for a Facility, for the purpose of this Rule, shall be calculated as follows: 

(i) The sum of the Potentials to Emit for all existing Permit Units as defined pursuant to 

District Rule 1301(TT); and 

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(ii) Any emissions increases from proposed new or modified Permit Units as calculated 

pursuant to subsection (B) above; and 

(iii) Any Emission Reduction Credits issued and banked pursuant to the provisions of 

District Regulation XIV shall be included in the calculations of a Facility's Potential to 

Emit. 

[SIP: Submitted as amended 03/25/96 on _______; Submitted as ammended 10/27/93 on 03/29/94; Conditional Approval 47 

FR 25013, 06/09/82] 

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