Bulk Gasoline Terminal Compliance: NSPS XXa, NESHAP Subpart R & 6B — What Changed and What Operators Must Do Before 2027
- 4 days ago
- 8 min read
Reflects EPA’s May 2024 final rule (89 FR 38508). Monitoring frequency thresholds, emission limits, and applicability definitions are current as of publication.
Who This Guide Is For
This guide is written for environmental managers, compliance officers, and terminal operators at bulk gasoline facilities classified as major or area HAP sources. It covers applicable regulations, technical changes, LDAR program structure, Appendix K OGI requirements, and the specific actions facilities should be taking now to meet the May 2027 deadline.
This article is based on insights shared during Alliance Technical Group's recent webinar on the EPA's Bulk Gasoline Terminal Rule updates. For a deeper discussion of the requirements, compliance timelines, and implementation considerations, watch the full webinar on demand.
The EPA's 2024 final rule is the most significant overhaul of bulk gasoline terminal air regulations in over forty years. New Source Performance Standards Subpart XXa and revised NESHAP Subparts R and 6B tighten loading rack emission limits by as much as 97%, replace monthly AVO inspections with formal LDAR instrument monitoring, and add CEMS, flare monitoring, and electronic reporting obligations that many terminals have never managed before. For existing sources, the compliance deadline is May 8, 2027.
The deadlines vary by regulation and source type. Here is the full compliance timeline:
Regulation | Source Type | Compliance Deadline |
NSPS Subpart XXa | New / modified / reconstructed (after June 10, 2022) | July 8, 2024 or upon startup |
NESHAP Subpart R & 6B | New / reconstructed sources | July 8, 2024 |
NESHAP Subpart R & 6B | Existing sources | May 8, 2027 |
NESHAP R & 6B — certain storage tank controls | Existing sources | May 8, 2034 |
The Three Rules Governing Bulk Gasoline Terminals
Three federal regulations now govern bulk gasoline terminals. NSPS 40 CFR Part 60, Subpart XXa applies to terminals that commenced construction, modification, or reconstruction after June 10, 2022, and replaces the older Subpart XX for those sources. NESHAP 40 CFR Part 63, Subpart R covers major source gasoline distribution terminals. NESHAP 40 CFR Part 63, Subpart BBBBBB (6B) covers area source facilities including bulk terminals, bulk plants, and pipeline facilities.
Subpart XX (40 CFR Part 60) remains in force for sources built or modified between December 17, 1980, and June 10, 2022. Many facilities will operate under both Subpart XX and XXa simultaneously, with different rules for different units within the same fence line. Identifying which subpart governs each affected unit is the necessary first step.
What the Rule Actually Changed
Loading Rack Emission Limits
The amended rules cut allowable loading rack emissions substantially from the prior Subpart XX standard of 35–80 mg/L:
NSPS XXa (new sources, thermal oxidation): 1 mg/L TOC
NSPS XXa (modified/reconstructed, thermal oxidation): 10 mg/L TOC
NSPS XXa (VRU-controlled): 550 ppmv new; 5,500 ppmv modified/reconstructed
NESHAP Subpart R: revised from 35 mg/L to 10 mg/L
NESHAP Subpart 6B: revised from 80 mg/L to 35 mg/L
Terminals with older vapor recovery units or thermal oxidizers should evaluate now whether existing control equipment can meet the new thresholds or whether upgrades are required before compliance deadlines arrive.
Storage Tank Requirements
Internal floating roof (IFR) tanks must maintain vapor concentrations above the floating roof below 25% of the lower explosive limit (LEL), with annual LEL monitoring now required. External floating roof (EFR) tanks face additional fitting control requirements aligned with NSPS Subpart Kb. Certain storage tank provisions under NESHAP Subparts R and 6B are delayed until May 8, 2034, but that delay applies only to specific tank control provisions. LEL monitoring and IFR vapor space requirements for new sources are not among the delayed items.
New Monitoring and Control Equipment Requirements
Beyond emission limits, the rule adds: flare monitoring requirements modeled on EPA's refinery rules; continuous temperature monitoring for vapor combustion units; CEMS for VRUs where concentration-based limits (ppmv) are elected instead of mass-based limits; submerged fill requirements for loading racks; and electronic reporting under all three regulations. Some area sources under Subpart 6B may be required to install CEMS for the first time.
LDAR: The Biggest Operational Shift for Most Terminals
Before these rule changes, LDAR at bulk terminals meant monthly AVO inspections. The amended rules replace that framework entirely. All equipment in gasoline service, including valves, pumps, connectors, pressure relief valves, sampling connections, and open-ended lines, is now subject to formal instrument monitoring. Open-ended lines are no longer permitted and must be capped or plugged.
Method 21 or OGI: Choosing Your Approach
Terminals can comply using Method 21 or Optical Gas Imaging under Appendix K. Method 21 uses a portable hydrocarbon detector with surveyor contact at each component; a reading at or above 10,000 ppmv is a leak. It builds on a component inventory, making it a natural fit where that inventory already exists or state permits already require Method 21.
OGI under Appendix K uses an infrared camera to survey equipment areas without component-by-component contact, six to twenty-two times faster than Method 21, and does not require a detailed component inventory, only an equipment list and route map. OGI does require a structured compliance program under Appendix K (see section below). Alliance Technical Group provides both Method 21 and Appendix K OGI services with nationwide scheduling capacity.
Repair Requirements
First repair attempt: within 5 days of detection.
Final repair: within 15 days.
If a repair cannot be completed within 15 days, the component must be tagged, the delay documented, an expected repair date established, and management sign-off obtained and recorded. LDAR reports, which are structured differently from standard semiannual air compliance reports, must break out total leaks by detection date, monitoring method, and component type, and flag any instance where a 5-day repair attempt was not made.
If You Choose OGI: What Appendix K Requires
Appendix K to 40 CFR Part 60 is a structured federal protocol that governs every aspect of OGI survey conduct, documentation, and quality assurance, from technician qualification and site-specific monitoring plans to daily weather verification and video recordkeeping. Terminals that elect OGI, or that hire vendors to conduct OGI surveys on their behalf, need a site-specific program that satisfies all of the following.
Technician Qualification
Initial training requires classroom instruction on the regulation and camera theory, three hours of field observation, twelve hours of side-by-side work with a qualified senior operator, fifteen hours of supervised surveying, and a final skills assessment. Semiannual performance audits and biannual refresher training are ongoing requirements. A senior OGI operator under Appendix K must have more than 1,400 documented lifetime survey hours and at least 40 survey hours in the preceding 12 months.
Site-Specific Monitoring Plan
Each facility requires a written monitoring plan covering interference conditions and stop/pause criteria (steam, fog, solar glare, heat reflections); safety protocols; required instrumentation (anemometer, temperature gauge, distance meter); camera calibration and maintenance; and defined operating envelopes for the specific camera model(s) in use, accounting for all configurations — lens type, sensitivity mode, handheld vs. tripod, external display use.
Survey Execution and Daily QA
Each survey day begins with a verification check — or a full field check if operating outside the camera’s defined envelope. Two viewing angles per scene are required, with dwell time minimums: at least 10 seconds per angle for scenes of 10 or fewer components, and at least 2 seconds per component for larger groupings. Weather conditions (ΔT and wind speed) must be recorded at the start and end of each survey and rechecked every two hours for surveys exceeding four hours. A five-minute QA verification video must be recorded each survey day. Confirmed leaks and completed repairs both require video documentation.
Storage Tank Emission Testing: A Methodology Problem Most Operators Don’t Know They Have
Regulators are increasingly requesting emissions testing directly from storage tank vents. What many terminal operators don’t realize is that standard single-point testing can significantly overstate a tank’s actual emission rate — and agreeing to that test plan without discussion can produce a number that follows the facility for years.
A storage tank and its headspace form a closed equilibrium system. When a test draws flow from the vent, it disturbs that equilibrium and induces additional evaporation. The more flow pulled during sampling, the higher the measured emission rate — not because the tank emits more under normal operation, but because the act of testing is generating the emissions.
The defensible approach is a regression-based methodology: test at three distinct exhaust rates each separated by at least 500 scfm, measure VOC concentration at each rate, plot emission rate against flow rate, and extrapolate back to zero imposed flow. The intercept represents the tank’s natural breathing rate without any test-induced draw. Alliance Technical Group has developed and applied this regression-based methodology in regulatory settings where the resulting emission rate was later scrutinized by state agencies — and the approach has held up under that review.
Five Actions Bulk Gasoline Terminals Should Take Now
With the May 2027 compliance deadline approaching, facilities should be planning today. Permit modifications, equipment procurement, vendor availability, and initial monitoring requirements can take much longer than expected.
1. Determine Applicability Across Your Facility: Identify which tanks, loading racks, and equipment are subject to Subpart XX, XXa, R, and/or Method 6B requirements. Then create a compliance roadmap that aligns with the 2024, 2027, and 2034 deadlines.
2. Make Key Compliance Strategy Decisions Early: Decide whether your LDAR program will use Method 21 or Optical Gas Imaging (OGI) under Appendix K. Also determine whether you'll comply with emissions limits using a mass-based approach or a concentration-based approach that requires CEMS. These decisions impact equipment, staffing, training, testing, and reporting requirements.
3. Evaluate Air Permit Impacts: Review existing permits to identify needed updates. Many facilities will need permit modifications to address new control requirements, LDAR provisions, CEMS monitoring, averaging periods, and revised emission limits. Start discussions early, as agency review timelines can be lengthy.
4. Secure Vendors and Compliance Resources: Demand for OGI specialists, Method 21 technicians, CEMS providers, and stack testing services is expected to increase as 2027 approaches. Engage implementation partners now to avoid scheduling constraints later.
5. Develop a Compliance Plan and Assign Ownership: Establish a detailed project schedule that works backward from the compliance deadline. Assign internal owners for permitting, LDAR, monitoring, testing, reporting, and recordkeeping activities to keep implementation on track.
How Alliance Technical Group Can Help
Alliance Technical Group is one of the few environmental services firms that provides stack testing, LDAR, CEMS, and permitting support under one roof — which matters when a compliance program spans all four. Our terminals team includes Appendix K-certified OGI operators with nationwide coverage, in-house spectroscopists for Method 320 FTIR work, and laboratory infrastructure in St. Louis and Minneapolis for developing site-specific response factors on ethanol-blended streams.
Alliance's offerings for bulk gasoline terminals include:
LDAR programs using Method 21 or OGI (Appendix K) — certified operators, nationwide scheduling
Stack testing: Method 25A and Method 320 (FTIR) with in-house response factor development for ethanol and oxygenated blends
CEMS installation, performance specification testing, and ongoing RATA services
Storage tank emission testing using regression-based methodology
Applicability determinations, permit revision support, and multi-year compliance planning
Regulatory References
40 CFR Part 60, Subpart XX — Standards of Performance for Bulk Gasoline Terminals (sources through June 10, 2022)
40 CFR Part 60, Subpart XXa — Standards of Performance for Bulk Gasoline Terminals (sources after June 10, 2022)
40 CFR Part 63, Subpart R — NESHAP for Gasoline Distribution Facilities (Major Sources)
40 CFR Part 63, Subpart BBBBBB (6B) — NESHAP for Gasoline Distribution Area Sources
Federal Register, May 8, 2024 — Final Rule: 89 FR 38508
40 CFR Part 60, Appendix A-7, Method 25A and Method 320
40 CFR Part 60, Appendix K — Optical Gas Imaging Monitoring Protocol
Frequently Asked Questions
Specific applicability and compliance questions terminal operators commonly ask about NSPS Subpart XXa and the revised NESHAP Subparts R and 6B.