EPA Tanks 4.09d: Shortcomings and Alternatives?

EPA Tanks

For many years EPA implemented Tanks4.09d (Tanks 4 for short) as a traditionally steadfast tool that estimates the amount of tank emissions released. This computer software program calculates volatile organic compound (VOC) and hazardous air pollutant (HAP) emissions from storage tanks to stay in sync with compliance and constant regulatory changes.

The desktop software manages different types of tanks, as stated below (check recent AP 42 Chapter 7 proposed revisions):

  • Vertical and horizontal fixed roof tanks
  • Internal and external floating roof tanks
  • Domed external floating roof tanks
  • Underground tanks

It didn’t come as a shock when recently EPA announced their detachment from Tanks 4.09d and refuted to acknowledge it as a viable tool to estimate emissions for different tanks.

DREEM Solutions Storage Tanks emissions module is a robust and affordable solution that was created to overcome Tanks 4.09d shortcomings and is continuously being updated to accommodate recent calculation changes proposed by EPA in 2018. Click Here to complete Contact Us form for your 30-days free trial.

Tanks 4.09d Main Shortcomings

For a long time, the industry itself and EPA were well aware of the flawed limitations within the EPA tanks software. These small yet significant shortcomings could pose long term detrimental effects. Some of the well-known Tanks 4.09d shortcomings are:

  • Bulk temperature calculations: – While calculating bulk temperature of non-heated tanks, the average annual ambient temperature of tank location was used in the software. This technical breakdown might sound reasonable in words; however, the underlying problem became apparent through calculation of monthly emissions. Variations of months and temperatures resulted in underestimation or overestimation. This calculation also affects the surface temperature calculation as it is derived from tanks bulk temperature.
  • The interpolation method pinned down 100F as the cut off maximum temperature according to which vapor pressure of heated tanks was calculated. This is more than often inaccurate because in a majority of cases the temperature in heated tanks exceeds 100F. Subsequently, inaccurate emissions results were generated because temperatures above 100F were not considered.
  • With heated tanks, Tanks 4.09d assumes full tank insulation which means that standing loss is always zero where in fact the tank roof might not be fully insulated; as a result, you will not be counting for standing loss in those cases.
  • There was no feature or option in Tanks 4.09d to flag whether stock used in floating roof tanks was heated or not. Once again, this led to misleading emission results for floating tanks.
  • Tanks landing and tanks cleaning calculations were not performed in EPA storage tanks.

Evidently, there were many errors in the software but the primary problems were inaccuracy, over or under estimations based on bugs in the software and lack of optional features.

Our Solution for storage tank emissions calculations

DREEM Solutions recognizes all of the above issues when dealing with tanks, it not only offers an alternative solution for those shortcomings in storage tank 4.09d,but it also provides a more comprehensive way to deal with tanks and any other source type at your facility with higher accuracy, less complications, and a more user-friendly interface. In summary:

  • Calculation of monthly and annual emissions from tanks are more accurate.
  • Emissions calculation for periods less than a month (when your tanks stock changes in the middle of the month for example).
  • Calculations are based on AP-42 chapter 7 equations.
  • Report of 12 months rolling total and average on throughput and emissions.
  • Capacity to run multiple tanks at once and no need to generate a report for each tank separately.
  • Report customization to comply with either EPA or your local agency requirements.
  • Comparison of metrics on a time basis for a source by source using a powerful business intelligence module.
  • Allows you to compare against emission and throughput limits or any limit enforced by your permits.
  • Ability to group your tanks based on permit grouping or actual physical locations within your facility.

About DREEM Solutions

DREEM Solutions understands the need for record-keeping and reporting of your environmental and sustainability data. Our software allows companies to stay in sync with environmental& sustainability requirements through accurate calculations and data analysis. You can easily keep track of data and metrics for air emissions,greenhouse gases, water, waste and a variety of other sustainability metrics for record-keeping, analysis, and reporting. Fill out Contact Us form to request a demo know more about our software and how we can help you with your storage tanks emissions calculation and estimation and other environmental requirements.

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