Keeping water out of underground storage tanks is just as important as keeping the stored fuel safely inside. But while modern, well-maintained tanks seldom let in water from the surrounding soil, it continues to make its way into the fuel.

Rodney Carter, managing director of Petroman Environmental Services, says: "Water gets in the only way it can down the vent pipes. The caps on the top of vent pipes only protect them from rain that is coming straight down from above or directly behind any other direction and rain will inevitably be blown in.

"Traditional vent caps offer no protection against fog, mist or just moist air that causes condensation on cold pipes," adds Carter. "Once the moisture is in the pipes, gravity will do the rest, taking it down to enter the tank."

To prevent atmospheric water getting into fuel storage tanks and aggravating biofuel problems, Petroman has introduced new vent pipe caps. "The caps themselves are simple devices with nothing to go wrong, but to perform properly they must be set up properly and aligned in the correct manner," says Carter. "Petroman can install the new caps on a complete set of vent pipes in less than an hour, with no disruption to forecourt operation."

Edward Wheeler, managing director of Eurotank Environmental, says that a retailer’s emphasis needs to be changing from keeping fuel out of the ground to keeping water out of their tanks.

"Before biofuels, if water entered an underground tank, it could simply be pumped out into the site interceptor with no serious consequences. With the introduction of both ethanol and biodiesel, any water that leaks into the tank can cause serious and expensive problems with customer vehicles and lost product through phase separation in petrol. Both of these problems can cost many tens of thousands of pounds for a single incident.

"Removing water from fuel storage tanks is not as straightforward as it might sound," adds Wheeler. "Water is heavier than both petrol and diesel, and will always find its way to the bottom of a tank. Using a basic standpipe to remove water will not guarantee that all water has been removed.

"Eurotank uses an endoscope camera system to run along the bottom of a tank after the initial water level has been removed. Pockets of water along the floor and water at the end of tanks if the tanks are sitting at an angle in the ground can be removed, and the Eurotank endoscope operator can confirm that the tank is completely free of water and issue a water-free certificate in confidence."

Wheeler says there are three places where water can enter into a tank. "One is via tank shell failure, the attached pipework or through the tank lid where considerable amounts of water sit above the tank in the underground access chamber," he says. "The industry has already moved to double-wall tank storage and now double-wall pipework is starting to become more popular, so it is only a matter of time before the underground fuel system is completed by double-wall chamber systems."

Eurotank can supply the new ZCL Composites double-wall tank chamber, which is based on the same technology as the manufacturer’s double-wall fibreglass tanks and the Phoenix tank lining system, for which Eurotank is the licensee in the UK. A Parabeam 3D fibreglass fabric is sandwiched between two fibreglass laminates to create a single laminate that can be monitored using a Class 1 pressure system. "I think it is the future and promotes a quality fuel installation, which can be permanently monitored," says Wheeler.

Vapour management

Meanwhile, Petroman estimates that it is helping retailers save more than one million litres per year with three devices installed into the tanks and pipework. There are more than 400 of the Petroman Vapour Management Control (VMC) systems installed on forecourts throughout the UK and Ireland.

The three elements of the VMC system combine to retain as much petrol vapour as possible on the forecourt and turn it back into saleable product, instead of returning it via the vapour recovery hose to the delivery tanker.

The three-stage process works by reducing the amount of vapour created when petrol deliveries are made through the use of the Petroman Softfill perforated beam, mixing the existing vapour back into the fill stream through Petroman’s Accumulus valve, and balancing vapour pressure across all tanks to reduce the amount of vapour that is sucked back into delivery tankers.

John Ryeland, managing director of George Hammond Retail, says: "It is clear that the VMC system has made substantial savings for the business by retaining fuel product that is rightfully ours in the first place within the tank farm and reducing wet stock losses.

"Having the benefit of a spread of sites, with and without VMC and ATC pumps, we have been able to isolate the results of the system. We are now planning to install VMCs in all new installations. We have seen increases in tangible stock retention across the three sites where we have already installed the equipment. I have proved to my satisfaction that it saves me money."

According to David Charman of Parkfoot Garage in Kent, his site lost 7,700ltrs in 2008-9 and 6,000ltrs in 2010. Since fitting the Petroman equipment in the third week of January 2010, the story has turned around completely. In 2010-11, the site actually gained 1,638ltrs of petrol in its two tanks, and up to May 2012 it had gained 1,776ltrs.

Petroman’s Carter adds: "If every garage selling more than two million litres of spirit per year fitted our system, we estimate we could retain 3,000 litres of petrol in forecourt tanks, rather than it going back to the oil companies. This is product that retailers have paid for and paid tax on. We calculate that this represents a saving of £26.30 per tanker.

"As well as saving retailers money, if we were able to retain the full amount of product, this would represent an annual reduction of 6,257 tanker movements. All this is achieved with no electricity costs and no requirement for space on the forecourt; all the equipment is powered by flow from the delivery and pressure, and the valves are mounted with the existing vent pipes."

Preventing biofuel problems

The properties of biofuels, which are now being included in virtually all petrol and diesel, are causing a range of problems for many fuel retailers, and these problems are only going to increase as the percentages of biofuel increase. Microbial contamination in diesel tanks can cause pumps to run slowly, filters to continually clog and pump motors to burn out. Worse case scenario is customer vehicles breaking down after filling up with contaminated fuel, leaving the retailer with a hefty bill to settle.

DP Fuel Tank Services (DP FTS) recommends regular tank cleaning to prevent these problems. Nigel Plumb, director of DP FTS, says: "All the advice from the US and Australia, where they have had biofuels longer than we have, is that it is vital to have a clean tank when dealing with biofuel.

"Our experience has shown that removing the fuel and thoroughly cleaning all sediment from the tank will cure a clogging problem caused by sediment. It will also remove bacterial colonies and algae clinging to the inside of the tank or in the residual sludge.

"If the volume of fuel and contamination is such that it cannot be sold through, or its safe disposal would represent too much of a financial loss, it is worth considering fuel polishing," adds Plumb. "This is where contaminated fuel is put through a series of filters to clean it. For optimum results, we recommend the processed fuel should then be delivered to a cleaned tank. If the contamination is heavy, the fuel may have to go through the filters more than once."

The reason that fuel polishing and tank cleaning go together is that there is little point in returning polished fuel to a contaminated tank, or contaminated fuel to a clean tank.

"Once you have clean fuel in a clean tank, we would recommend keeping it that way. As each new tanker load can bring in fresh biological contamination and, possibly, water, we believe it is prudent to schedule regular fuel analysis. This may lead to further polishing and cleaning, but taking action early will reduce subsequent costs and disruption."

Tank lining

The UK has an ageing population of underground tanks and pipework, particularly in the dealer sector, according to Francis Hollier, director of construction and forecourt services at Vianet Fuel Solutions. "It is probably a matter of when steel tanks and pipework underground fail rather than if they do rust is somewhat inevitable," he says.

"We are also seeing issues where heavily broken, unrepaired surfaces have allowed shock to transfer and fracture shallow-run pipework.

"If fuel is being lost during periods with no sales, retailers should immediately contact Vianet or another specialist to arrange a fuel uplift or transfer before embarking on a testing programme, and subsequently planning remedial action and improvement."

A more financially viable alternative to digging up the forecourt and putting in new tanks is lining the existing tanks. "Vianet offers guaranteed single- and double-skin lining systems," says Hollier.

"Single-skin lining is a cost-effective option for increasing the life of storage tanks. While a single-skin lining is not monitored by a direct leak detection system, we do offer the solution in conjunction with our Clearview real-time wet-stock monitoring option. We are offering one year free real-time wet-stock monitoring and leak detection with every single-skin lining.

"Our TUV/London Fire Brigade-approved double-skin system uses quality materials and refined processes to form a true ’tank within a tank’, incorporating a class 1 leak detection system.

"Vianet tank lining is a genuine solution, not a stopgap."

Moving on

Exit Strategy Planning (ESP), a scheme set up to aid those wanting to sell their redundant forecourts for as much as possible, has been launched by DP Fuel Tank Services (DP FTS) and Legacy Development Initiatives (LDI).
The aim is to give forecourt owners a third option when their business comes to an end, as opposed to making the choice between selling the land to developers for an extremely low price, or solid filling the tanks to make them safe; a very costly alternative, and leaving the land unused.
Nigel Plumb, director of DP FTS, says: "We are regularly contacted by independents who would like to retire but cannot afford to, or feel they are trapped by their own sites. We are often asked to make tanks safe on sites that have had to stop trading, and there is no real prospect of retrieving the full value of the land; so it’s good to finally have the ability to do more to help them."
ESP, DP FTS and LDI have produced a package that takes the retailers painlessly through the entire process of maximising the value of their property before selling it.