UST Fill Pipe Protection
Written by: Brian Pottebaum, Director of Training Services
When ordering fuel for your underground fuel tank, there are many questions you should be asking yourself beyond, “How much room do I have in that tank?” Some of those other questions include: “Is the transport going to be able to lock on tight to my fill pipe?” “Is the spill bucket cleaned out, and can it provide adequate storage in the event of an overfill or spill?” and “Is the overfill prevention free from obstruction?”
These are all good questions to ask yourself, and a good transport driver will let you know if any of these items are not adequate. Aside from not being properly prepared, the automatic tank gauge and other monitoring equipment will not detect spilled fuel during delivery.
Petroleum releases can and do occur when fuel is delivered into a tank. It is important that the fuel transport can lock on tight to the delivery fill pipe. If the fill pipe is not tight and the fuel extends above the spill bucket, the fuel can spray outside the bucket or even overflow. After every load, you should check the fill pipe adaptor, because it can loosen, or the O-ring can become dislodged when the delivery hose is moved. A loose or compromised adaptor can be another way for fuel to spill during delivery.
Spill buckets need to be inspected frequently. Proper maintenance of your spill buckets can be a major tool in preventing ground contamination. If a spill bucket is completely full of water or fuel, there is no room for additional spilled fuel to be contained. Spill buckets must be kept clean and empty.
When checking the spill bucket and fill pipe adaptor, you should also examine the fill pipe to ensure there are no obstructions in the drop tube, which typically includes the overfill shutoff valve. Approximately 84% of the USTs in Iowa have a shutoff valve installed to prevent the tank from being overfilled. Obstructions prevent the valve from closing properly, allowing the tank to be overfilled. Federal regulations only allow a fill up to 95% capacity in a tank with a shutoff valve. A tank measuring stick is commonly used to disable the valve. If you do find anything obstructing the valve, you need to contact your service company to check the valve for proper operation before the next delivery. It may have been malfunctioning prior to the drop, or possibly damaged when the stick was forced down the fill pipe. If you don’t have that type of overfill protection, you may have a ball float restrictor valve (vent line) or an overfill alarm as part of the tank monitor system. These devices must also be checked for operation. The transport driver is likely the best person to ask if everything is operating properly.
Other components in the fill area that should be inspected routinely include the spill bucket cover/lid, fill pipe cap, and the drop tube (with or without the shutoff valve) in the fill pipe. Spill bucket lids can be a serious problem if they are resting on the fill riser pipe attached to the tank. Industry standard advises 4-6” clearance between the fill cap and the spill bucket lid. If a vehicle drives over the lid resting on the fill cap, it will apply direct pressure on the riser that is connected to the top of the tank. This will damage the fill cap and possibly compromise the integrity of the tank structure. If you have a situation where the lid does not fit properly over the tank, you should contact your service company to correct the situation immediately. Lids that are damaged or do not fit properly can also create a nightmare for you when trying to keep your spill bucket clean.
When not being used, the fill pipe must be properly capped, otherwise water and debris can get into the tank. Check the fill cap for any damage, and make sure the gasket is still in place. The cap must snap down tight to ensure a tight seal on the fill pipe.
Although the drop tube is not always a requirement, it is a good idea to have one in the fill pipe. If you have a shutoff valve in the fill pipe, the drop tube is part of that device. The drop tube must be installed within 4-6” of the tank bottom. It is supposed to reduce the amount of agitation or disturbance when filling the tank. When agitation is limited, it reduces the amount of vapor being released to the atmosphere. You are losing fuel every time you smell vapor. It is a very dangerous situation if vapor collects near a fire or spark, or if they enter the store. Vent pipes must be installed properly, including proper height, protection, and separation from structures.
Fuel vapors can be released on any part of the tank system that is not tight, such as a loose cap on the tank monitor probe. Vapor leaks are a significant factor causing releases and subsequent environmental remediation. Tank systems must be installed properly and maintained, so the system is tight and vents properly to the environment.
As you can see, there are many things to keep track of when receiving fuel. Routine inspections are very important and will aid in preventing releases and ultimately expensive environmental cleanup. It is your responsibility to make sure your system is functioning properly.