Uni-Contain: New Design for Service Stations

Underground tank systems installed with the wave of a magic wand? Not quite that quickly, but close. Bruce Lewolt reports.

What would typically take several weeks was completed in just 15 minutes. An underground fuel tank, piping system, pumps, and electrical conduit — complete with canopy support structure and foundation — were set and level in a hole, ready to be back-filled. The first US installation of a modular gas station was completed in September in the Los Angeles suburb of Tujunga.

Such efficiency was made possible by pre-assembly of the parts comprising a modular unit. All of the equipment mentioned above works together as a unit that can simply be taken off the truck and placed in the hole. There is no need to erect the individual pieces on site.

Known as Uni-Contain, the modular system is engineered and built in a clean factory environment and shipped to a job site ready to install. With up to 80 percent of the construction process complete, on-site requirements are kept to a minimum. Since the Uni-Contain goes into the ground as a modular unit, it can also be taken out and relocated as a modular unit. This advantage has attracted the attention of the military, the mining industry and other groups needing temporary, movable fueling stations.

With the Uni-Contain, companies can progress from a bare hole in the ground to pumping gas in two weeks or less — in some cases, much less. In August, a station in Finland turned the project around in just four days.

The Uni-Contain is delivered to the job ready to be installed. This picture shows the Uni-Contain on a large truck.

The Uni-Contain can accommodate any fuel storage need, from a small, one-island, 6,000-gallon system to a large multi-island truck stop with 40,000 gallons or more of storage. Since this technology eliminates the need for a dedicated tank farm area in the parking lot, stations can now be located on properties that are often considered too small for normal gas station construction. On normal-sized lots, the technology allows the owner to dedicate more space to the C-store or to install more islands and dispensers.

Weather incentive
The concept was originally developed in Northern Europe to address the problems that harsh weather posed to installers. In the late 1980s, service-station systems were installed in Europe much like they are in the United States today. A contractor would order hundreds of parts and components from one or more distributors.

The parts were then delivered to the job site where a team of installers took six to 12 weeks to assemble them into a working forecourt (a European term for the area that contains the tanks, piping, islands, dispensers and canopy—basically everything except the C-store and other buildings).

The hole can be backfilled to the top of the tank as soon as the unit is set in the ground.

In Europe, bad weather has had an extremely negative impact on the quality of station installations. When it isn’t raining in Northern Europe, it is usually snowing or blowing cold winds out of the Arctic north, making it difficult, at best, to complete the job with conventional systems.

Oy U-Cont, the largest fuel tank manufacturer in Northern Europe, teamed up with the major oil companies across the continent to achieve two major objectives for service stations. They aimed to develop a system that could be installed quickly and that would increase the quality control of the gas station by decreasing the possibility of leaks to the ground with the system’s secondary containment chamber.

Initially, some European oil companies were concerned about how the under-island tanks would be filled without interrupting station operations. Several systems were developed to solve this problem. Some of the solutions provide an option for the fill to be under the canopy, which also eliminated the possibility of rainwater getting into the manway.

The idea of putting the tank under the island had been around for years. The configuration reduced the amount of pipe in the ground, and the forecourt itself occupied a smaller footprint because no extra space was needed for a tank-farm area. The problem with the concept was finding a place to put the canopy column footings since the tank is positioned directly under the canopy columns.

Architects and engineers looked into the possibility of attaching the canopy columns directly to the steel tanks; however, the forces exerted by wind on the canopy, and by uneven freezing in the ground, meant the relationship of the canopy columns to the tank might constantly change. Over time, this could lead to metal fatigue, which would then lead to tank failure.

Uni-Contain being craned into position in Tujunga, California.

The golden arch
The proverbial lightening struck Oy U-Cont’s president, a young engineer by the name of Jari Sistonen. He surmised that a cement and steel rebar system could be constructed in the form of an arch that would take the stress load of the canopy around the tank. He called this the A-Frame.

All the weight of the dead load and any live loads (wind, snow, rain, earthquakes and hurricanes) would be transferred around the tank to the concrete foundations located on both sides of the tank. These foundations can also be used to secure the tank hold down straps to counteract buoyancy created by high water tables. The foundations and A-Frames are designed and manufactured in accordance with strict specifications set out by an independent engineering firm to meet national seismic zone 4 and other standards. This patented system can hold up under huge snow loads in Siberia, Russia, as well as California’s earthquakes.

The next step was to develop a system where the pumps, piping and electrical conduit could be pre-installed and tested in a clean, well-lit factory environment. The solution was a chamber that could be attached to the tank like a sump. This chamber created a secure, leak-tight, protected housing for the piping, pumps, sensors, electrical and other components. The ground could freeze and thaw repeatedly, and the pipe would never move.

If the piping were to develop a leak, it would be contained inside this leak-tight chamber. Sensors would then activate a shut-down of the pumping equipment and alert the operator to the leak. Afterward, the chamber could easily be cleaned out from a manway access at the surface level, eliminating the need to bring in a backhoe to dig up pipe or clean up of any contaminated soil.

The containment chamber enabled Oy U-Cont to develop cleanup and repair procedures that could get a system back in operation after a leak as quickly as 24 hours. Normally, a major pipe leak causing ground contamination would take weeks to clean up with conventional methods.

Piping and equipment are factory installed inside a secondary containment chamber.

Installation results
The first Uni-Contain system was installed in Finland in 1992. Since that time, hundreds of Uni-Contain units have been installed in locations around the globe. No leakage of fuel to the ground has been reported in any of these installations.

According to contractors around the globe, permitting for the system has proved to be easier than that for conventional installations. From Saint Petersburg, Russia, to Los Angeles, California, Uni-Contain systems have been successfully permitted and installed.

Fullerton-based Diamond Point Construction bought and installed the unit in Tujunga. Owner Karl Watkins said he was amazed at how quickly the County of Los Angeles approved this first Uni-Contain installation. That county is reputedly one of the toughest locales in the United States for gas station permitting. The fire inspector, for instance, commented on the fact that the pipe was pre-installed and tested in a clean factory environment. Since the unit arrived at the installation site ready to test, it saved time for the inspector. He was able to inspect all of the pipe at one time instead of needing to return to the site on several different days.

Major oil companies throughout Europe have used the Uni-Contain since 1992. Shell Oil’s Glen Marshall, P.E., learned about the Uni-Contain system while on a fact-finding tour in Europe two years ago. He pushed for Oy U-Cont to bring the system to the United States because he felt the technology would solve some problems involved with gas station installations. Oy U-Cont teamed up with ITEQ, one of the largest producers of US fuel tanks, to represent the technology in North, South and Central America, as well as parts of the Pacific Rim. ITEQ owns Trusco Tank and Brown Minneapolis Tank.

Marshall describes why the innovation works. “With the A-Frame, the tank does not know that the canopy is there, and the canopy does not know the tank exists. They operate completely independently of each other.” As a result, this system has been able to pass full seismic four (4) zone requirements, a must for installation in many parts of the Americas.

The electrician on the first US Uni-Contain installed in Tujunga, California, said the installation was “a dream” for his crew. During the installation, the temperature averaged 102 degrees, and the smog was so thick “you could cut it with a knife.”

His installers simply ran electrical conduit from the power source to the conduit that was stubbed out at the Uni-Contain. Once this was connected, they pulled wire through the conduit. All the back-breaking, tedious, metal bending at the turbine and under the dispenser, which normally takes place under the hot sun, was already done for them at the factory.

The owner of the station in Tujunga will get his business back 30 days sooner than if conventional installation techniques had been used. When taking into consideration the money made during these 30 days, the cost of the system is far less than conventional construction. Even without those earnings, the cost is less.

Risers are installed to street level prior to final backfill and pouring of a pad.

Upgrades and approvals
Housing the pipe in an accessible chamber eliminates the need to cut through the concrete pad and dig piping trenches through the dirt. The Uni-Contain can be used with any UL-listed underground storage tank. Also UL-listed are the tank and system that connect the secondary containment chamber to the tank. The Uni-Contain also meets all applicable NFPA, UFC and SBCCI fire codes. Currently, the Uni-Contains are manufactured using the SuperTank or the Titan Tank.

Thus far, the largest US response to Uni-Contain has come from hypermarkets that are looking to install service stations. Such stores want a quick installation process to avoid losing a percentage of their sales during conventional development. This development may take as long as two months, with construction trucks, barricades and a large hole in the ground deterring customers from driving into the parking lot.

By all accounts, if patterns follow successful European trends, Uni-Contain could well be the wave of the future for gas stations.

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