CARB staff propose Excel-only submissions, 30 MB appendix limit and revised 'unusual/large leak' definition for 2026 NGLA reporting
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Summary
CARB staff proposed limiting appendix files to 30 MB, requiring Excel spreadsheets instead of PDFs, removing the 24-hour requirement from the Appendix 8 unusual/large leak definition, and noted October 2025 changes to Appendix 9 emission factors; staff set March 31 template issuance and June 15 reports due.
CARB staff outlined proposed changes to the 2026 Natural Gas Leak Abatement (NGLA) reporting template, including file-format and size limits and revisions to how utilities may designate events as "unusual or large" for year-over-year emission analyses.
Andrew Maroka of the California Air Resources Board told attendees the agency will request that each appendix submission be limited to 30 megabytes and submitted as an Excel spreadsheet rather than a PDF, though staff said utilities may petition staff for exceptions if they have special circumstances. "We request the file size per appendix submittal be limited to 30 megabytes," Maroka said.
Why it matters: CARB staff said oversized or non-editable files have impeded internal review and data transfers. The Excel requirement aims to reduce follow-up correspondence and speed analyses; staff will add the language to the March 31 data-request email.
Maroka also proposed removing the 24-hour duration criterion from Appendix 8’s current definition of an "unusual or large" leak. Under the current wording read in the meeting, unusual/large leaks are events that "result in the uncontrollable release of natural gas to the atmosphere for more than 24 hours." The proposed definition would instead let utilities describe the event’s cause, magnitude and mitigation and petition CARB management for categorical exemption if the event would disrupt year‑over‑year emission analysis. Maroka said CARB management will review petitions and inform utilities of decisions.
On Appendix 9, Maroka informed attendees of an October 2025 revision to emission factors used for vehicle-based reporting at transmission and distribution metering and regulating stations. He demonstrated unit conversions used to translate the EPA tables from SCF hydrocarbons per hour to MSCF natural gas per day and showed side-by-side comparisons of previously distributed values and the October revisions (example shown by staff: a valve factor listed as 10.5 SCF/hr translating to 0.257 MSCF/day).
Utility commenters pressed staff on details. Sri Khan (PG&E) noted some appendix files—especially Appendix 6—exceed 30 MB and asked how to request exceptions; staff said utilities should correspond with CARB if larger files are necessary and suggested providing a separate worksheet that holds formulas if the submitted sheet uses pasted values. Isaac Marcia (PG&E) flagged apparent discrepancies between control-valve emission factors across appendices and asked CARB to align Appendix 2 and Appendix 5/9 values; staff asked PG&E to send the request and said they were attempting to obtain background from EPA on recent table changes.
Next steps and deadlines: CARB staff said they will correspond with utilities prior to March 31, issue the revised template on March 31, accept emission reports by June 15, issue follow-up questions in July, complete internal finalization by Aug. 31, circulate a draft report to utilities by Nov. 16 and publish the final electronic report by Dec. 31.
The presentation closed with an offer to continue discussion by email and at the end of the workshop.
