Two numbers decide what has to happen at a gasoline drop: 10,000 gallons a month and 100,000 gallons a month. Under the EPA area-source air rule for gasoline dispensing facilities, a station at 10,000 gallons a month or more has to be filled through a submerged fill pipe. At 100,000 gallons a month or more it needs a full Stage I vapor balance system rated at 95 percent efficiency, and the driver has to connect the vapor hose on every single delivery. When that hose stays coiled on the bobtail, the paperwork says the station owns the violation. In practice the jobber usually ends up paying for it.
The two thresholds, and the rule number people get wrong
The federal rule for the station side is 40 CFR 63 Subpart CCCCCC, the area-source NESHAP for Gasoline Dispensing Facilities. It sorts sites into three buckets by monthly gasoline throughput.
- Under 10,000 gallons a month. Minimal requirements. Do not spill, do not overfill, keep the fill cap tight, keep monthly throughput records so you can prove which bucket you are in.
- 10,000 gallons a month or more. Everything above, plus a submerged fill pipe on every gasoline tank. For fill pipes installed on or before November 9, 2006, the discharge opening has to sit no more than 12 inches off the tank bottom. For anything installed after that date, no more than 6 inches.
- 100,000 gallons a month or more. Everything above, plus a Stage I vapor balance system designed for 95 percent control efficiency, vapor-tight connections with poppeted dry breaks, drop tubes in the gauge wells, and pressure/vacuum vent valves on the tank vent risers.
Jobbers cite Subpart BBBBBB for this all the time. BBBBBB is the area-source rule for bulk gasoline terminals, bulk plants, and pipeline facilities. That is your yard, not your customer's forecourt. If you are pulling regulation text to settle an argument with a dealer, pull CCCCCC.
One detail that catches people: once a site crosses a threshold, it stays subject. A station that hits 100,000 gallons during a good summer month does not fall back out of the vapor balance requirement when December is slow. It is a one-way door.
How to tell which of your sites is over the line
Monthly throughput is gasoline only. Diesel, kerosene, and DEF do not count toward it, and they carry no Stage I obligation at all. So a truck stop pushing enormous diesel volume can still sit under 100,000 gallons of gasoline and legally take a drop with no vapor return.
If you want a fast gut check on a dealer site whose volume you do not track directly, work backward from their fuel sales. For the week ending July 6, 2026, the EIA national average retail price for regular gasoline was $3.78 per gallon (EIA), so 100,000 gallons a month is roughly $378,000 in monthly gasoline revenue at the pump. A site doing under about $250,000 a month in gasoline is almost certainly under the threshold. A site clearing $450,000 is almost certainly over it, and the vapor hose is not optional there. Pump prices move, so do not memorize the dollar figures. Divide the site's monthly gasoline revenue by whatever regular is averaging that month, and compare the gallons to 100,000.
Your own delivery history is the better source. If you supply the station, you already know its gallons to the load. Pull twelve months of drops per site and flag anything that touched 100,000 in any single calendar month.
Coaxial versus dual-point: what the driver is actually connecting
A vapor balance system is a closed loop. As gasoline goes down into the tank, an equal volume of gasoline-saturated vapor gets pushed out of the ullage space, and instead of venting to atmosphere it travels back through a hose into the empty compartment on the bobtail. The truck goes home with the vapor. That loop only closes if the driver hooks the second hose.
Dual-point (two-point)
Two separate risers into the tank, each with its own adapter at the sump. One is the product fill, usually a 4-inch fitting. The other is a dedicated vapor riser, commonly 3-inch or 4-inch, with a poppeted dry-break vapor adapter that only opens when the driver's coupler engages it. The driver drags two hoses. This is the standard for newer installs and it is what most air districts prefer, because the vapor path is short and straight.
Coaxial
One riser doing both jobs. A coaxial adapter carries product down the inner passage and returns vapor through the concentric annulus around it. The driver uses a coaxial hose and coaxial elbow. Fewer penetrations into the tank, fewer holes to leak, and it fits older sites where there is no room to add a second riser. The catch is truck equipment. A bobtail set up only for dual-point cannot service a coaxial site, and a driver who shows up without the coaxial elbow either leaves without dropping or drops without vapor. That second option is the one that generates violations.
Real hardware on both sides comes from a short list of makers: OPW, EMCO Wheaton, Husky, and Morrison Bros. all build Stage I adapters, dry breaks, and coaxial fittings. Nothing exotic. The failure is almost never the part. It is the truck not carrying the right one.
Whose violation is it
Federally, the affected source under Subpart CCCCCC is the gasoline dispensing facility. The station owner is the one required to have the vapor balance system, to keep it in working order, and to not accept a delivery unless the vapor line is connected and the cargo tank holds a current vapor-tightness certification. If EPA or a delegated state agency writes it up, the notice of violation lands on the dealer.
That is the federal answer. It is not the whole answer. Most state and local air district rules also name the transferor, meaning the party physically making the transfer, which is your driver. California, Texas, and a long list of ozone nonattainment districts write the delivering carrier into the enforceable duty explicitly. And the cargo tank side is squarely yours regardless: the bobtail needs an annual vapor-tightness certification (EPA Method 27 pressure and vacuum test), and the driver has to be able to produce it.
Then there is the commercial layer. Read your supply agreement. A well-drafted jobber contract assigns delivery-related environmental liability somewhere specific. If yours is silent, you will be arguing about it after the fact with a dealer who is holding a five-figure penalty letter and a signed BOL with your driver's name on it.
The money, worked out
Clean Air Act civil penalties are inflation-adjusted every year and the statutory ceiling now runs above $100,000 per day per violation. Nobody pays that for a missed vapor hose. Real settled GDF cases land far lower, and a defensible planning range for a documented Subpart CCCCCC vapor balance violation is roughly $2,000 to $10,000 per day of violation, driven by gravity and by the economic benefit of noncompliance.
So run it. A 120,000 gallon-per-month station takes about three drops a week. A driver who has been skipping the vapor connection for one quarter has 36 or so delivery days on the record, and those days are documented, because the BOLs are all sitting in the dealer's file. Thirty-six days at $2,000 is $72,000. At $10,000 it is $360,000. Against that, a coaxial elbow and a vapor hose kit for the bobtail is a few thousand dollars once.
There is also product in it. Vapor balance exists because gasoline vapor is gasoline. It is a small volume per drop, and it is the kind of quiet loss that hides inside a shrink number nobody investigates, which is the same pattern behind most of the leaks in where fuel margin actually disappears.
California does not care about your throughput
CARB runs its own program. Phase I Enhanced Vapor Recovery, or EVR, requires certified equipment operating at 98 percent efficiency, and it applies to gasoline dispensing facilities essentially regardless of monthly volume, with only narrow exemptions for very small aboveground tanks. Every component has to be listed on a CARB Executive Order, and the components must be used in the exact certified combination. You cannot mix a CARB-approved adapter with an uncertified coupler and call it compliant.
For a jobber operating in California, or hauling into California from a neighboring state, that means the truck side has to match the EVR configuration on the ground. It is one of the few compliance areas where the federal floor is genuinely less demanding than the state ceiling, in the same way that state-level card and payment rules can sit on top of the federal baseline described in EMV and PCI compliance at the pump.
Make it a dispatch problem, not a driver problem
Every jobber I have worked with who solved this solved it in the back office, not in the cab. The site record needs three fields the driver can see before he rolls: gasoline throughput bucket, Stage I configuration (none, coaxial, or dual-point), and the vapor adapter size. Then the truck gets loaded with the right hardware and the BOL prints a vapor-connect line the driver signs. It is not hard. It just has to live somewhere other than one dispatcher's memory. That is exactly the kind of per-site attribute we built FastDragon to carry, because the moment it lives only in a person's head you are one vacation away from a violation.
Audit your sites once. Fix the truck kits once. Then the question of whose violation it is stops being interesting, because there is not one.
Questions people ask
Does a diesel-only drop need any vapor connection?
No. Stage I vapor recovery under Subpart CCCCCC and under CARB applies to gasoline. Diesel, kerosene, heating oil, and DEF have no vapor balance requirement because their vapor pressure is low enough that displaced vapor is not a regulated air toxic in the same way. The tank still needs to be filled properly and not overfilled, but there is no vapor hose.
Is Stage II still required? My dealer says his nozzles got decommissioned.
Stage II is the vapor recovery that happens at the nozzle when a customer fuels a car, and it is separate from Stage I. EPA removed the federal requirement for new Stage II systems in 2012 because onboard refueling vapor recovery, the carbon canister built into every car since the late 1990s, does the same job. Many states then allowed or required decommissioning. Stage I at the drop was never affected by that and is still fully in force.
How often does the bobtail itself have to be tested?
Gasoline cargo tanks that deliver to sites subject to the vapor balance requirement need an annual vapor-tightness certification, typically an EPA Method 27 pressure and vacuum test. The documentation has to be available, and a station that accepts a load from an uncertified cargo tank is itself out of compliance. Keep the current certification in the truck and a copy in the file, because dealers under audit will ask for it.
What applies to my own bulk plant, not the station?
That is Subpart BBBBBB, and it sorts your plant by average daily gasoline throughput rather than monthly volume. Under 40 CFR 63.11086, a bulk plant at 4,000 gallons a day or more has to load gasoline through a vapor balance system; below that, the requirements are mostly submerged fill and good housekeeping. Note that 4,000 gallons a day is roughly 100,000 to 120,000 gallons a month, so the bar is in the same neighborhood as the 100,000 gal/month station threshold, not dramatically lower. The practical point stands: check your own daily average against 63.11086 before assuming you are exempt, because a growing plant can cross that line without anyone noticing.
Can a driver legally refuse to drop if the vapor riser is damaged?
Yes, and he should. If the vapor adapter will not seat, the poppet is stuck, or the riser is bent, connecting is impossible and dropping anyway creates a documented violation for the site with your BOL as evidence. The right move is to leave, document the defect with a photo, and let the dealer repair it. A refused drop costs a delivery. A completed one with no vapor return can cost far more.