We have made it into June and the
Annual Emission Inventory reporting season has passed for all Arizona air quality jurisdictions! As this reporting is still fresh in our minds, we wanted to take a quick moment to reflect on the 2024 emissions inventory process, identify key takeaways from this year’s experience, and present tips to keep in mind for making next year’s reporting go smoothly.
Best Practices
One of the essential items for facilities reporting annual emissions is keeping an updated internal emission inventory (EI) spreadsheet. Keeping an up-to-date spreadsheet that is consistent with the facility’s air permit is one of the most effective ways to stay organized. The facility can also utilize data gathered monthly as part of 12-month rolling emission spreadsheets to prepare for future emissions inventory reporting.
These EI spreadsheets serve as important tools to reference sources of emission factors, usages, and assumptions as this information will likely be questioned by the agency reviewing your facility’s EI. Spreadsheets can also be a good record to have in the event of staff turnover or other facility changes. Having clear references for input data and methodologies is also important because a Certification of Truth, Accuracy, and Completeness (CTAC) is submitted alongside an EI, noting that the submittal is based on information that is true, accurate, and complete. The clearer and cleaner your EI spreadsheet, the easier reporting becomes! Keep clear records of what was updated, when, and why to answer any questions that may arise in the future.
Data Upload
- Submission Requirements: In MCAQD jurisdiction, facilities required to submit EIs are emailed typically in January. Facilities are required to submit via the AQD Online Portal. For ADEQ, all Class I Facilities are required to submit via CAERS. Class II Facilities will be notified by ADEQ whether an EI submittal is required and have the choice to submit via CAERS or through the ADEQ form.
- Emission Factors: Unless this information is already referenced in an EI calculation attachment associated with the submittal, include comments identifying the sources of inputs and emission factors. Adding sufficient information reduces the number of questions regulators would ask.
- Process SCC codes: Make sure to assign the appropriate process Source Classification Code (SCC) for the operations at your Facility. These SCCs classify different types of activities and processes that generate emissions. If your facility’s emission factors are based on the SCC, assigning a code that is not representative could result in miscalculating emissions. For example, SCC 10100203 for an external combustion boiler should not be used for a diesel engine. If the facility inventory on the respective portal was set up by the agency, make sure to verify the SCC being assigned and correct it if needed. To verify this information, EPA and agencies have published a variety of tools such as the EPA WebFire search tool or the MCAQD list of SCCs. If there is missing SCC information for emission sources being reported, the portal will not allow complete validation and submittal to occur.
- For CAERS specifically, an SCC code can only be used once, or else an error will occur. An example of this would be reporting multiple haul truck trip emissions under 30501024. A common remedy to this issue is changing the seasonal operating schedule for processes that fall under identical SCCs.
- Cleanliness: Small refinements can make your emission inventory clearer and easier to follow. This can include updating out-of-date comments or references and ensuring a consistent number of significant figures are used (Trinity recommends using 3 significant figures in most cases).
Start Early
A recommendation we like to emphasize each year is the importance of starting your reporting early! Whether you are a new facility reporting for the first time, have made recent changes to your facility and permit, or are operating the same way you have for a long time, it is best to start organizing data and preparing for emission inventory reporting well before the regulatory deadline.
For new facilities the first step should be creating or reviewing your facility setup in the respective reporting database.
- For new facilities in ADEQ: the agency requires you to request facility creation in CAERS as they will not automatically do this. By requesting access too close to the reporting deadline, facilities risk inaccurate representations or potentially having to create the facility profile themselves. Existing facilities should also review their facility setup, in case changes and revisions need to be made from the past years reporting. It is the facility’s responsibility to have an up-to-date facility setup for reporting.
- For Maricopa County: Maricopa County Air Quality Department (MCAQD) will automatically create your facility in the AQD Portal; however, both new and existing facilities should set aside plenty of time to review how their facility is set up in the portal and ensure emission units, processes, and controls are consistent with the air permit representation.
When reviewing the Facility set-up, it is also important to ensure the proper facility contacts are listed on file. This check includes verifying the submitter/certifier, the preparer, and adding any new facility contacts or external consultants that may be supporting the EI submittal. Waiting too long to review this information could lead to delays in the reporting process and late submittals.
As for EI spreadsheets, revisions and edits do not have to occur only during reporting season; changes can and should be made year-round. Pushing off these updates can cause unnecessary stress and burden when coming up against regulatory deadlines. Something to consider when modifying and revising your permit is setting a reminder to update these spreadsheets in real time as changes are implemented at your facility.
Key Takeaways and Finalizing Your Report
Emissions reporting can be a complex and time-consuming effort. The tips listed above are recommendations to keep in mind to ensure reporting go smoothly.
Additionally, once a draft report is ready for your facility, we suggest doing quality checks to ensure you are accurately representing operations at your facility. At minimum, the following checks are recommended to avoid regulatory and compliance risks:
- Compare your reported emissions of pollutants to their respective permit limits: This is to ensure they are below limits (hint: there may be throughput limits too, so check for these as well!). If needed, refinements to material throughputs or calculation methods can be made to avoid inaccurately reporting higher emissions.
- Compare your reported emissions to prior years to check for consistency: In comparing reported emissions to prior years, facilities can find possible errors or inconsistencies. If large increases or decreases in emissions are reported, air quality agencies may ask for reasons why. Facilities should be well-prepared for this scenario.
- Compare your EI to your other environmental reports which utilize the same source data: Differences between reports could be flagged by software to regulators and raise questions. For example, your calculated air emissions for a pollutant that appears on both the EI and on your Toxics Release Inventory (TRI) report should be consistent in most cases. Discrepancies between reports could lead to the need to prepare of revised reports, explain errors, and decrease regulator and public trust, resulting in higher scrutiny and additional site inspections from regulators.
Annual Emission Inventory reporting is an important responsibility every year and presents unique challenges to many facilities. If you find that you are in need of additional support to meet your Arizona reporting requirements, feel free to email
Joseph Lynch in Trinity’s
Phoenix office or call
602.274.2900.
