This method may be used to develop an editable spreadsheet containing detailed emissions calculations for emissions from storage tank operations at your facility. These instructions are used to calculate volatile organic compounds (VOCs) and individual and total hazardous air pollutants (HAPs) emissions. Potential emissions of other pollutants from storage tank operations will also need to be included in the permit application (e.g., emissions from fuel combustion for heating stored materials). Each step in your calculation(s) needs to be clear and easy to follow.
Note: Certain tanks are insignificant activities under Minn. R. 7007.1300 and it may not be necessary to calculate emissions from these sources. For example, gasoline storage tanks with a combined total capacity of less than 2000 gallons represent an insignificant activity which is not required to be listed in a permit application. Refer to the instructions for Form IA01 for further information.
Include the following information with your calculations:
 AQ Facility ID No. — Include your Air Quality (AQ) Facility identification (ID) Number (No.). This is the first eight digits of the permit number for all permits issued under the operating permit program. If your facility has never been issued a permit under this program, do not include it at this time.
 AQ File No. — Include your AQ File Number, if known. This number can be found in the “cc” section of correspondence from the Minnesota Pollution Control Agency (MPCA). If you don't know or can't find this number, do not include it at this time.
 Facility name — Include your facility name.
 Storage Tank identification number(s) — Include the identification number of the storage tank (TK# or EQUI#). Obtain this number from Form GI05C or the appropriate form related to the permit you are applying for, or your existing permit.
 Heaters, if applicable — If there are fuel combusting heaters associated with this tank, indicate the number of heaters, the fuels which can be used, and the total rated heat input of each heater. Be sure to calculate emissions from the heaters as shown on the webpage for External Combustion Units. If the heaters use electric heat, there would be no emissions.
 Type of Tank — Indicate the type of tank and follow the calculation instructions as shown.
 Formula/Equation — For each calculation step, the formula and/or equation needs to be available in the spreadsheet cell .
 Operating limitations — Describe in detail any permit limits you plan to take to restrict your potentialtoemit (production limits, bottlenecks, etc.  see Proposing Synthetic Minor Permit Limits). Attach additional information, as needed. Describe the limiting factors, cite any rules that apply (e.g., Standards of Performance for Stationary Sources [NSPS, 40 CFR part pt. 60], Best Available Control Technology [BACT]). The associated limit must be used to calculate your potentialtoemit after permit limits (Limited Emissions). If you used vendor certification or stack test data to limit your potentialtoemit, the factor you used will become your permit limit. Include all proposed limits on Form CD01, and anywhere else as instructed in the application forms.
Emissions calculation instructions
TANKS Emissions Estimation Software, Version 4.09d is no longer supported by EPA. The MPCA will no longer be accepting emissions data using the software in permit applications. Existing, permitted tanks which were previously approved using the TANKS software will not be affected. Calculations may be completed using a spreadsheet program with the equations and algorithms outlined in Chapter 7 of EPA’s AP42: Compilation of Air Emission Factors.
Part I. Fixed roof tank (vertical or horizontal)
Follow these steps for calculating and documenting the emissions for each fixed roof storage tank at your facility. Generally, each column of your spreadsheet will correlate to a step indicated below. Additional columns can and should be included in the spreadsheet to indicate additional steps or information specific to your tank. See the table below as an example format. This is only an example, and any format displaying the information clearly can be used.
Example Format

Maximum Unlimited Emissions (lb/yr) 
Maximum Unlimited Emissions (tpy) 
Limited emissions (tpy) 
Actual Emissions (tpy) 
Proposed Operating Limitations 

VOC – Standing loss 





VOC – Working loss 





VOC – Total Loss 





HAP 1 – Standing loss 





Etc. 





Step 1. Pollutant
List each pollutant (VOC, each individual HAP, total HAPs) and whether the calculation is for the standing loss, working loss or total loss.
 VOC = volatile organic compounds
 HAPs = hazardous air pollutants – each individual hazardous air pollutant. See EPA's Web site for more information.
 Total HAPs = All HAPs added together
Step 2. Maximum unlimited emissions, lbs/yr
Document the potential uncontrolled emissions, calculated using equations and algorithms referenced in Chapter 7 of AP42, in pounds per year, for standing losses and working losses for each pollutant. Add them to obtain the total losses.
Step 3. Maximum unlimited emissions, tons/yr
Document the potential uncontrolled emissions in tons per year by dividing Maximum Unlimited Emissions (lb/yr) by 2000 lb/ton, for standing and working losses. Add them to obtain the total losses.
Step 4. Limited emissions
(Skip this item if these calculations are for Registration Permit Option D.)
The Limited Emissions are determined by taking into account all proposed limitations on operation of the source in the emissions calculations. An example of such a limitation might be the amount of tank throughput. Calculate the limited standing and limited working losses using the equations and algorithms found in Chapter 7 of AP42. Add the standing and working losses to obtain the total losses.
Step 5. Actual emissions
If this is an existing tank and historical records exist, determine actual emissions by using the equations and algorithms in Chapter 7 of AP42 and the average of the previous two calendar years of usage data. If this is a new unit or no records exist, use the equations and algorithms in AP42 and a reasonable estimate of the tank’s actual throughput. Report actual emissions in tons/year.
Step 6. Operating limitations
Describe the proposed limitations used to calculate the Limited Emissions. Be sure to include all proposed limitations on Form CD01.
Part II. Internal floating roof tank
Follow these steps for calculating and documenting the emissions for each internal floating roof storage tank at your facility. Generally, each column of your spreadsheet will correlate to each step indicated below. Additional columns can and should be included in the spreadsheet to indicate additional steps or information specific to your tank. See the table below as an example format. This is only an example, and any format displaying the information clearly can be used.
Example Format

Maximum Unlimited Emissions (lb/yr) 
Maximum Unlimited Emissions (tpy) 
Limited emissions (tpy) 
Actual Emissions (tpy) 
Proposed Operating Limitations 

VOC – Rim Seal loss 





VOC – Withdrawal loss 





VOC – Deck Fitting Loss 





VOC – Deck Seam Losses 





VOC – Total Loss 





HAP 1 – Rim Seal loss 





Etc. 





Step 1. Pollutant
List each pollutant (VOC, each individual HAP, and/or total HAPs) and whether the emissions are rim seal loss, withdrawal loss, deck fitting loss, deck seam loss, or total loss.
Step 2. Maximum unlimited emissions, lbs/yr
Document the potential uncontrolled emissions, calculated using equations and algorithms referenced in Chapter 7 of AP42, in pounds per year, for rim seal losses, withdrawal losses, deck fitting losses, and deck seam losses. Add them to obtain the total losses.
Step 3. Maximum unlimited emissions, tons/yr
Document the potential uncontrolled emissions in tons per year by dividing Maximum Unlimited Emissions (lb/yr) by 2000 lb/ton, for all the types of losses. Add them to obtain the total losses.
Step 4. Limited emissions
(Skip this item if these calculations are for Registration Permit Option D.)
The Limited Emissions are determined by taking into account all proposed limitations on operation of the source. An example of such a limitation might be the amount of tank throughput. Calculate the rim seal losses, withdrawal losses, deck fitting losses, and deck seam losses using the equations and algorithms referenced in Chapter 7 of AP42. Add them to obtain the total losses.
Step 5. Actual emissions
If this is an existing tank and historical records exist, determine actual emissions by using the equations and algorithms in Chapter 7 or AP42 and the average of the previous two calendar years of usage data. If this is a new unit or no records exist, use the equations and algorithms in AP42 and a reasonable estimate of the tank’s actual throughput. Report actual emissions in tons/year.
Step 6. Operating limitations
Describe the proposed limitations used to calculate the Limited Emissions. Be sure to include all proposed limitations on Form CD01.
Part III. External floating roof tank
Follow these steps for calculating and documenting the emissions for each external floating roof storage tank at your facility. Generally, each column of your spreadsheet will correlate to each step indicated below. Additional columns can and should be included in the spreadsheet to indicate additional steps or information specific to your tank. See the table above as an example format. This is only an example, and any format displaying the information clearly can be used.
Example Format

Maximum Unlimited Emissions (lb/yr) 
Maximum Unlimited Emissions (tpy) 
Limited emissions (tpy) 
Actual Emissions (tpy) 
Proposed Operating Limitations 

VOC – Rim Seal loss 





VOC – Withdrawal loss 





VOC – Deck Fitting Loss 





VOC – Total Loss 





HAP 1 – Rim Seal loss 





Etc. 











Step 1. Pollutant
List each pollutant (VOC, each individual HAP, and/or total HAPs) and whether the emissions are rim seal loss, withdrawal loss, deck fitting loss, or total loss.
Step 2. Maximum unlimited emissions, lbs/yr
Document the potential uncontrolled emissions, calculated using equations and algorithms referenced in Chapter 7 of AP42, in pounds per year, for rim seal losses, withdrawal losses, and deck fitting losses. Add them to obtain the total losses.
Step 3. Maximum unlimited emissions, tons/yr
Document the potential uncontrolled emissions in tons per year by dividing Maximum Unlimited Emissions (lb/yr) by 2000 lb/ton, for rim seal losses, withdrawal losses, and deck fitting losses. Add them to obtain the total losses.
Step 4. Limited emissions
(Skip this item if these calculations are for Registration Permit Option D.)
The Limited Emissions are determined by taking into account all limitations on operation of the source you are proposing to comply with in this application. These limitations include limits on the amount of tank throughput, for example. Calculate the rim seal, withdrawal, and deck fitting losses using the equations and algorithms referenced in Chapter 7 of AP42. Add them to obtain the total losses.
Step 5. Actual emissions
If this is an existing tank and historical records exist, determine actual emissions by using the equations and algorithms in Chapter 7 or AP42 and the average of the previous two calendar years of usage data. If this is a new unit or no records exist, use the equations and algorithms in AP42 and a reasonable estimate of the tank’s actual throughput. Report actual emissions in tons/year.
Step 6. Operating limitations
Describe the proposed limitations used to calculate the Limited Emissions. Be sure to include all proposed limitations on Form CD01.