Phase 1 containment sump system for petroleum fueling facility underground storage tanks

A containment system for a fuel site according to the present invention comprises: a fuel storage tank; at least one fuel line connected to the fuel storage tank; a containment sump associated with the fuel storage tank and encircling the at least one fuel line connected to the fuel storage tank; an opening in the containment sump through which external connections may be made with a remote end of the at least one fuel line; and a removable catch basin adapted to fit into the opening in the containment sump and to fit over and around the remote end of the at least one fuel line such that the catch basin can catch fuel spills from the remote end of the at least one fuel line.

FIELD OF THE INVENTION

The present invention relates to containment sump systems for containing spillage of gasoline dispensed to underground storage tanks at filling stations and preventing overfilling of the underground storage tanks.

BACKGROUND

Gasoline and other petroleum based fuels are dispensed to motorists and other users from underground storage tanks (USTs). The USTs are filled periodically from tanker fuel trucks with hoses connected to the fill port (or fuel drop tube) and in most cases, an additional hose is used to vent the vapors displaced from the UST as the fuel level rises back to the tanker truck to form a closed loop system. The process of UST filling and vapor recovery is called Phase 1 vapor recovery, as shown inFIG. 1.

To minimize the potential of fuel spilled from the fuel delivery process entering the surrounding area or soil, as shown inFIG. 2, a spill containment sump20(commonly referred to as a “spill bucket”) is used to hold any fuel splashed or drained from the fuel transfer hose. Fuel collected in the spill containment sump20is typically drained back into the drop tube unit21through a valve22operated by the delivery driver.

Spill containment units can be either the direct burial or the containment sump type. Overall, the petroleum industry is shifting towards constructing spill containment systems with tank top containment sumps, as shown inFIG. 5, because they provide an additional level of leak protection. One application of the present invention involves an integrated tank top containment sump spill containment system.

In addition, USTs are typically equipped with an overfill protection device to prevent excess fuel from being delivered to the tank. These devices fall into two categories, ball floats and flapper valves. Ball float devices, as shown inFIG. 3, are installed in the UST vapor vent line24. As the fuel level rises, a floating ball25rises up and eventually seals off the escaping vapors, preventing any additional fuel from entering the tank. Flapper valves, as shown inFIG. 2, are installed on the fill pipe21(also called the “drop tube”). As the fuel level rises, a float attached to a valve mechanism23closes off the flow of fuel.

There are a number of problems with the current state of the art of spill containment and overfill protection devices. A large percentage of recently installed spill containment devices fail periodic leak testing. Also, a number of overfill prevention devices fail vapor integrity tests and frequently have mechanical problems that prevent accurate and reliable overfill protection. Also, current spill containment sumps are difficult to properly install and service.

Another problem with current Phase I UST fueling devices is the inability of the vapor piping system to completely contain UST ullage vapors. If the UST is exposed to excess pressure, fuel vapors can escape out of the vent vapor connection while the hose nozzle is being connected to the poppet adaptor by the delivery truck driver. This is both a potential exposure risk to the delivery truck driver, as shown inFIG. 4, and a source of fugitive emissions of volatile fuel vapors26. The various embodiments of the present invention represent a significant improvement over existing Phase I vapor recovery, overfill protection and spill containment systems.

SUMMARY OF THE INVENTION

A containment system for a fuel site according to the present invention comprises: a fuel storage tank; at least one fuel line connected to the fuel storage tank; a containment sump associated with the fuel storage tank and encircling the at least one fuel line connected to the fuel storage tank; an opening in the containment sump through which external connections may be made with a remote end of the at least one fuel line; and a removable catch basin adapted to fit into the opening in the containment sump and to fit over and around the remote end of the at least one fuel line such that the catch basin can catch fuel spills from the remote end of the at least one fuel line.

In one embodiment, the containment system according to the present invention also comprises a removable drip cap placed over and around the at least one fuel line and extending between the at least one fuel line and the removable catch basin such that fuel cannot drip down between the at least one fuel line and the removable catch basin into the containment sump. In a further embodiment, the removable catch basin comprises an upwardly extending side wall, and an upwardly extending inner wall lower than the side wall that encircles but is spaced from the at least one fuel line, and wherein the drip cap extends from the at least one fuel line over the inner wall of the catch basin but is spaced from a top edge of the inner wall such that the fuel filling the catch basis can drain into the containment sump. The catch basin may also comprise a drain and a drain line connected to the at least one fuel line in yet a further embodiment.

The present invention is directed in one embodiment to a tank top containment sump assembly for containing gasoline spilled during the filling of underground storage tanks at fueling facilities and/or for preventing the overfilling of the storage tanks.

The present invention in one embodiment also provides an improved method and device for filling underground storage tanks, preventing overfill of the storage tanks, and/or for containing spillage during the filling of the storage tanks.

DETAILED DESCRIPTION

In one embodiment, as shown inFIG. 6B, a tank top containment sump assembly is a continuous shape with two round upwardly protruding openings, one for a fuel delivery line27, and the other for a vapor riser connection28. Threaded onto each riser is a connection adaptor28afor delivery tanker truck nozzles. Installed below the connection adaptors are drip caps29. There is a seal between the adaptor and the drip cap. The drip cap is installed so that any fuel running down from the adaptor is directed into a containment reservoir or catch basin30. The drip caps are also designed for removal without disassembly of the riser adaptors to assist with rapid removal of the spill containment unit. The spill containment reservoir is installed beneath the drip cap so the shoulder of the drip cap overlaps the wall of the containment reservoir while leaving a gap to ensure spillage in excess of the reservoir's capacity is drained into the containment sump. The containment reservoir contains a drain valve32to drain spillage from the reservoir into the underground storage tank.

In the assembly or disassembly of this embodiment of the present invention, there is provided a reservoir or catch basin for collecting and containing fuel from a UST filling event of a continuous shape with two round openings protruding upwardly from the center of the basin, as shown inFIG. 8. The two openings43serve to allow the fuel delivery riser and vapor riser passage through the basin. The center of the basin contains an opening33through which the sump drain valve system passes. Attached over the openings in the catch basin, as shown inFIG. 6B, are two drip caps29, one screwed over the vapor riser connection, and the other screwed over the fuel delivery line.

Beneath the vapor riser connection, as shown inFIG. 6B, is an “EZ-Fit” connection30a(a 3A type sanitary fitting) attached to a 4″ section of removable flexible piping30b, at the end of which is attached another “EZ-Fit” connection30a. Below the bottommost “EZ-Fit” connection is a threaded pipe section31afor height makeup. Beneath the threaded pipe section is a sensor unit31b, a ball float riser proximity indicator for the sensor32aand a ball float overfill protection device32b. The sensor unit is connected to a j-box29afor an overfill valve and sensor which is connected to a solenoid actuator29b. The j-box is connected to a sump sensor27alocated beneath the j-box. The solenoid actuator is attached to a solenoid actuated overfill protection valve assembly27bwhich is attached beneath the drip cap over the fuel delivery line. Beneath the solenoid actuator is an “EZ-Fit” connection30a. Below the “EZ-fit” connection is attached the drain valve piping27c. Beneath the drain valve piping connection is a threaded pipe section31afor height makeup. Below the threaded pipe section is a vapor tight drop tube assembly28csealed at the top of the UST. Beneath the drop tube assembly is a drop tube29c. The parts used in the present invention may be made from fiberglass reinforced materials.

The drop tube sealing assembly, in one embodiment, as shown inFIG. 12, includes a riser tube47ehaving a proximal end with internal threads and an UST spaced apart from the proximate end of the riser tube. The UST contains a threaded inlet47awhich is positioned atop the tank. A standard pipe nipple47b, includes a first end in cooperation with the proximal end, an opposite end in connection with the threaded inlet, and an annular inner surface that forms a conduit. The inner surface comprises a female thread section. A drop tube adapter fitting47cis concentrically disposed within the pipe nipple. The adapter fitting contains an outer surface containing external threads in cooperation with the female thread section. A seal in the form of an O-ring is disposed between the adapter fitting and the pipe nipple. A drop tube47dhaving an open end is coupled to the adapter fitting.

The disassembly of this embodiment of the present invention, as shown inFIGS. 9A–D, begins as shown inFIG. 9Bby removing a 36″ manway and unscrewing the drip caps from the vapor riser connection and fuel delivery line. After the drip caps are removed, the spill containment basin is lifted up as shown inFIG. 9Cusing the foot operated drain valve. As the basin is lifted up, the dry break fitting on the drain valve is disconnected and the basin removed. Once the basin is removed, the electrical fitting to the solenoid actuated overfill protection valve is disconnected as shown inFIG. 9D. The two “EZ-Fit” clamp fittings are then removed, and the vapor and fill risers are then removed. This disassembly sequence can require less than one minute.

To drain the fuel from the spill containment basin into the UST, a drain valve, as shown inFIG. 11, is mounted at the lowest point of the basin. The drain valve comprises a dry break fitting34, a threaded fitting35, a compression spring36, a sealing gasket37, a connector rod37aand a foot valve pad38for manual draining. A float or electronically actuated valve may also be used for draining. The connector rod is connected to the foot pad at one end, and the sealing gasket at the opposite end. Attached to the opposite end of the sealing gasket is the compression spring which is connected at the opposite end to the threaded base. The threaded base is connected at its opposite end to the dry break fitting. To drain fluid from the basin, the operator applies force to the foot valve pad either by sliding laterally or by depressing the pad. Operation of the foot valve pad compresses the spring thereby depressing the sealing gasket, resulting in fluid draining through the opening. A replaceable metal mesh screen filter39may be placed around the opening in the basin to prevent debris from entering the drain valve and storage tank. The dry break disconnect fitting facilitates the removal of the spill containment basin.

Passing through the upward open protrusions in the spill containment basin, as shown inFIG. 6Bare a fuel delivery riser27and a vapor riser28. Threaded onto each riser is a connection adaptor28afor the delivery tanker truck nozzles. These adaptors allow the tanker truck fuel and vapor connections to be attached to the risers to allow fuel to be delivered to the UST and to allow vapor to be directed to the tanker truck.

Installed below the connection adaptors are drip caps42, as depicted inFIG. 7. Each drip cap comprises a collar40with interior threading fitting around the connection adaptor41. The collar flares outwardly41ato form a shoulder41band then turns downwardly to form a lip41c. There is a seal between the adaptor and the drip cap. Preferably, the seal is formed by an O-ring40areceived in a recess around the internal wall of collar40and a gasket40breceived in a downwardly facing recess such that the gasket is compressed against a flange on connection adaptor41when the drip cap is tightened into place. Extending laterally from the drip cap collar is a shoulder41bdirecting any fuel running down from the adaptor into the containment reservoir. The drip caps fit over the upward protruding openings in the containment reservoir. The drip caps are also designed for removal without disassembly of the riser adaptors to assist with rapid removal of the spill containment unit.

The spill containment basin is designed to nest, as shown inFIG. 6, onto the upper edge of the tank top containment sump top hat cylinder28b; however it is not attached to the top hat. This allows for rapid removal for service and maintenance of the sump and piping. The fuel fill and vapor riser drip caps are removed prior to removal of the spill containment basin. In one embodiment the capacity of the spill containment basin is at least five gallons.

Another feature of this spill containment system is that in the event of a quantity of fuel entering the spill containment basin greater than the capacity of the spill containment basin, the excess, as shown inFIG. 8will rise up and flow over the protruding riser openings43and be captured by the tank top containment sump. Then fuel proximity sensors located in the sump can trigger an alarm. The outside edge44of the containment sump basin is sufficiently higher than the riser protrusion openings to assure that all the overflow is directed to the tank top containment sump. Preexisting spill containment systems are unable to contain a volume of fuel greater than the rated capacity, thus the excess fuel flows over the top and either onto the ground or down into the underground storage tank.

Another feature of this spill containment system is the ability to rapidly remove the entire spill containment system (drip caps, spill containment basin, riser piping and hardware), as shown inFIGS. 9A–D. This feature makes it possible to combine all the necessary tank top connections into one tank top containment sump, as shown inFIG. 10. These items include a fill riser45aand vapor riser45b(both including extractor tee fittings), tank level monitor (TLM)45and turbine pump46. The savings to the petroleum industry can be significant due to the elimination of one tank top containment sump and associated fittings and manways for each UST. To facilitate the installation and maintenance of the one sump containing all four items, quick connect fittings would be used for the piping connections and for various sections of the piping risers.

Another feature of this design is that the drain valve discharge is not exposed to the UST ullage vapor pressure. The drop tube is sealed at the top of the tank, as shown inFIG. 12(please note other patent application by McGill and Wyper, U.S. Ser. No. 10/020,690, filed Oct. 29, 2001, which is incorporated herein by reference). Because the top of the drop tube47is sealed off from the ullage, all of the hardware and piping above that point is sealed from the ullage, similar to a p-trap or soda straw. A common failure point on ullage pressure testing of USTs is leakage from the spill containment sump drain valves. The fuel drain connection in this design is below the shutoff valve and above the drop tube seal.

A further feature of one design of the present invention is an electronically actuated overfill protection valve on the fuel drop fill pipe and an electronically actuated valve on the vapor connection riser. These features protect the delivery driver from fuel vapor exposure and minimize fugitive emissions from the UST system. The overfill protection valve in this design serves the same function as existing overfill protection devices, namely to prevent delivery of excess fuel to the UST greater than a fixed fill percentage, typically 95%. The overfill protection system presented in this design could be triggered by the existing electronic tank level monitoring system (TLM) controller (typically a Veeder-Root TLS 350 monitoring system, which is in use at many station sites) or, as shown inFIG. 14, from a dedicated float valve sensor48aintegrated into the ball float unit. The valve could be configured as a fail-safe unit so that if the actuator was not connected, the valve would be closed to prevent fuel from being delivered to the tank. The valves could also be mechanically actuated.

The overfill protection valve, as shown inFIG. 13would normally be in the closed position48. An electronic proximity sensor located in the vapor riser poppet valve unit would detect the connection of the vapor nozzle. After a preset time delay, the vapor and fill valves would open for fuel delivery. Both valves close immediately after the removal of the vapor nozzle or a signal from the TLM indicating the fuel level in the UST is greater than permitted. Also, the time delay opening the vapor valve permits the delivery driver to connect the vapor nozzle without exposure to the UST ullage fuel vapor pressure because the driver is connecting the nozzle to a closed valve. Again, these valves could be mechanically actuated.

Prior to filling the UST, the fuel delivery driver must manually gauge the UST with a tank gauge stick. This can be facilitated by pushing a special “TANK STICK” button on the control system console located in the station. This may also be facilitated by attaching the vapor nozzle first, which after the time delay will open both valves and allow a gauge stick to be inserted into the fill pipe to measure tank level. The fill valve will automatically close several minutes after the “TANK STICK” button is activated unless the vapor nozzle is connected.

The preceding description has been presented with reference to presently preferred embodiments of the invention. Workers skilled in the art and technology to which this invention pertains will appreciate that alterations and changes in the described structure may be practiced without meaningfully departing from the principal, spirit and scope of this invention. Accordingly, the foregoing description should not be read as pertaining only to the precise structures described and illustrated in the accompanying drawings. Rather, it should be read consistent with, and as support for, the following claims which are to have their fullest scope.