Who is responsible for preventing an overfill during a delivery?
On paper, the tank owner and operator; in practice, you share it. 40 CFR 280.30 says owners and operators “must ensure that the volume available in the tank is greater than the volume of product to be transferred to the tank before the transfer is made and that the transfer operation is monitored constantly to prevent overfilling and spilling.”
The federal underground storage tank (UST) rule puts the duty on the owner and operator. The transporter has its own. Under 49 CFR 177.834(i), a motor carrier hauling hazardous materials in a cargo tank must ensure a qualified person attends the tank at all times during unloading. That duty ends only once the carrier’s obligation is fulfilled, the tank is on the consignee’s premises and the motive power has been removed from the cargo tank and from the premises, so a driver who is still hooked up and still on site stays covered. Fuel is a hazardous material, and the same load carries the placard and shipping papers that put it under that rule.
So the owner must have the room and the equipment. DOT defines attending as a qualified person staying alert within 25 feet of the cargo tank, with an unobstructed view of the tank and hose to the maximum extent practicable, and in a normal drop that person is you. Neither duty covers for the other, and a state may add its own rules on top, so check the state you deliver in.
What does the driver check before connecting?
Confirm the tank can take the whole delivery, then confirm you know what will warn you. The federal rule makes room the owner’s job to ensure, but you are the one who finds out on arrival if nobody did.
The arithmetic is simple, and worth doing on paper every time. Say the tank holds 10,000 gallons, the gauge reads 4,100, and you plan to drop two compartments of 3,000 and 2,500 gallons.
| Step | Illustrative number |
|---|---|
| Tank capacity | 10,000 gal |
| Product already in tank (gauge) | 4,100 gal |
| Delivery planned | 5,500 gal |
| Level after the drop | 9,600 gal (96%) |
| Federal limit for an automatic shutoff (no more than 95% full) | 9,500 gal |
These figures are illustrative, not from any customer. The drop does not fit within the 95 percent point. A shutoff device set to close at 95 percent would stop the flow with product still on the truck, and without one you would be pushing past the point the equipment is built to protect. Deliver less, or call dispatch and the site before you connect.
Two details keep the math honest.
First, use physical gallons, because tank space is physical space. A tank gauge and a truck compartment measure gross gallons, the volume at its actual temperature, while a ticket or invoice may be priced on net gallons corrected to 60°F. If the paperwork shows net, do not subtract that figure from the room in the tank. Check which basis the quantity on your delivery ticket uses; how to read a fuel delivery ticket explains the fields.
Second, count the hose. EPA notes that a typical delivery hose can hold about 14 gallons of fuel, and you still have to place that volume after you close the truck valve.
Also look at the fill. Is the spill bucket empty and clean? Is the alarm panel powered? Is the right product going into the right tank? A wrong-grade drop is a different emergency, but this is the moment you catch it.
What will the tank do when it fills, and what do you do?
Match the device to the response. 40 CFR 280.20(c) lets a tank meet the rule with one of several kinds of overfill prevention, and each one tells you something different.
| Device | What you see or hear | When it acts (federal) | Your action | Who does what |
|---|---|---|---|---|
| Overfill alarm | A high-level alarm that must be where the delivery person can see or hear it | At no more than 90% full, or about one minute before overfill | Close the truck valve at once; do not wait for a second warning | Owner/operator: keep it powered, working and inspected. Driver (good practice): be there to hear it and respond |
| Automatic shutoff | Flow slows, then stops. Some shut off in two stages | At no more than 95% full, or before fittings on top of the tank are exposed to product | Treat a slowdown as a stop signal; close the valve and do not restart | Owner/operator: install, set and inspect it. Driver (good practice): do not keep forcing flow |
| Flow restrictor (ball float valve) | Flow drops from back pressure, but only on a tight tank top. On a loose one you may see nothing | At no more than 90% full, or 30 minutes before overfilling | Stop at any unexplained slowdown. Do not assume a quiet tank has room | Owner/operator: tank-top fittings and the device. Driver (good practice): watch the level and the hose |
EPA’s guidance warns that “overfill alarms work only if they alert the delivery person at the right time and the delivery person responds quickly.” It also says a ball float valve will not restrict flow if the tank has loose fittings or other non-tight tank-top components, and then an overfill will occur. That is the case where a driver who stops early is the only protection left.
Flow restrictors in vent lines cannot be used to meet the rule where overfill prevention is installed or replaced after October 13, 2015, so you will meet them mostly at older sites.
What does a driver do during and after the drop?
Stay within sight of the tank and the hose, and keep product moving only as long as the tank can take it. The DOT definition of attending is specific: a qualified person within 25 feet of the cargo tank, alert, with an unobstructed view of the tank and delivery hose to the maximum extent practicable, unless a remote video or sensor setup (which has its own conditions, including shut-off valves operable from the remote control station), a hose fitted with automatic shutoff devices (inspected before use, with the operation checked at least every 60 minutes), or another exception in the rule applies.
A working checklist:
Before:
- Read the gauge or ask the site for it, and write the number down.
- Add up what you plan to drop, in physical gallons, per tank.
- Find the fill pipe, spill bucket and alarm, and confirm the product.
- Check whether the tank has an alarm, shutoff or ball float, and where you will hear or see it.
During:
- Stay within 25 feet of the cargo tank, with a clear view of the tank and hose.
- Start slow and watch the flow.
- Treat any slowdown, horn or light as a stop signal.
- Do not silence or work around an alarm to finish the drop.
After:
- Close the truck valve and handle the hose only if the tank has room for what drains.
- Check the spill bucket for product before you leave.
- Record the actual quantity, tank and time on the ticket. If the site stopped you short, say why.
- Report any spill or overfill to the site and your dispatcher straight away. Section 280.30(b) requires the owner and operator to report, investigate and clean up spills and overfills under 40 CFR 280.53. Your company may have reporting duties of its own; your dispatcher will know which apply.
An overfill rarely stays one problem. It also becomes a delay, a short delivery and a dispute, and the time on site is evidence in each. If the site holds your truck, see detention pay in fuel trucking for how to document the wait. A shipper checking a carrier’s drop procedures is part of vetting an external fuel hauling company.
Does overfill protection apply to every tank?
No. Under 280.20(c)(2), a UST system filled by transfers of no more than 25 gallons at a time does not need the spill and overfill equipment. Most tanks you deliver bulk fuel into will not qualify for that, but a small tank might.
The rule also covers underground tanks only. An aboveground tank is outside Part 280 and sits under different rules, including state rules and, above certain sizes, the federal Spill Prevention, Control, and Countermeasure (SPCC) rule. 40 CFR 112.1 exempts a facility with no more than 1,320 gallons of aboveground oil storage, counting only containers of 55 gallons or more, and 42,000 gallons or less of completely buried storage; a facility must meet both limits. The guide on on-site fueling versus bulk tank delivery covers when a site ends up with each kind of tank. The carrier’s attendance duty under 177.834(i) does not depend on whether the tank is above or below ground.
How often is the equipment checked?
Under the federal rule, at least every three years. 40 CFR 280.35 requires overfill prevention equipment to be inspected at least once every three years, confirming it is set to activate at the correct level and will activate when product reaches it. The inspection is the owner’s duty, not yours, but it is why a quiet alarm is not proof the tank has room.
How Energy Connect handles it
On Energy Connect, carriers can bid on a posted load, and the poster can accept or decline each bid. The carrier can record dispatch, pickup, transit and delivery on the load, see the pickup, delivery and verification times, and attach the bill of lading and other delivery documents to it.