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Going underground
11 January, 2019

With all the talk (and hype) about electric vehicles, Edward Wheeler, group managing director at Eurotank, is concerned that there's a big risk that retailers will stop investing in their underground fuel systems, because they don't know what the future holds.

"The financial rationale to replacing underground tanks and pipework will be less clear as each year passes," he explains. "Digging up a site to replace a liquid fuel system, while the future of road transport fuels is not so clear, is perhaps unwise."

At the same time, he says the likely increase in biofuel (specifically E10) will probably place a strain on ageing, existing infrastructure.

"Seals and gaskets are most at risk from the introduction of E10. Unfortunately, tank gauge systems will not always detect water leaking into a tank containing E10 or even E5 petrol, as the water is absorbed before settling at the bottom of the tank and lifting the water float. When the petrol finally gets saturated with water, the water and ethanol will 'drop out' to the bottom of the tank. This process is known as phase separation. The result is a water bottom phase, containing ethanol/alcohol, which is a lighter density than pure water. This lighter density water/ethanol mix will not 'lift' the water detection float as the float is less buoyant in this mix."

Wheeler says the first a retailer will know that water has leaked in, is via customer complaints about vehicle breakdowns. "Since the introduction of E5, which happened more than 13 years now in the UK in some areas, we have dealt with countless incidents where water has leaked into tanks and has not been detected before customers break down. Retailers should make sure they are insured for this scenario and ideally invest in having their tanks and pipework checked and seals and gaskets replaced with the latest versions, which are needed for higher levels of alcohol." That's because vehicle damage and the cost of damaged fuel can easily run into thousands of pounds. "A high-end petrol car, in warranty, will often be given a new engine by the dealership, which the retailer's insurers will be asked to pay for. So, a single vehicle claim can be in excess of £10,000," explains Wheeler. He says that E10 is likely to mobilise sludge and rust in petrol tanks that are currently storing E5. This could then create filter problems in pumps and vehicles. Wheeler believes now is therefore a good time to clean tanks out, repair them and even reline them with materials suitable for alcohol-blended fuel. Eurotank has two tank lining systems. The first is Lifeliner, a double-skin tank-in-a-tank solution, which is resistant to up to 100% ethanol and methanol. The second is Fastliner, a lower cost, 'bladder' lining system, which lives up to its name with a very fast installation time of two-to-three days per tank from start to finish.

Wheeler says retailers should also be aware of the potentially damaging effect of methanol, which can be blended into petrol, on GRP tanks, seals and gaskets, which were not designed to come into contact with the chemical.

"As a very small molecule, methanol has the ability to penetrate and degrade unsuitable plastic material, which in the real world, can result in water leaking in and fuel leaking out."

According to Byron Barker, wet-stock operations co-ordinator at Suresite, a growing problem for his forecourt customers is diesel 'bug' an umbrella term for the various types of bacteria, fungi or algae that can propagate within modern blends of fuels.

"We have recently seen microbial growth in suction lines as well as tanks," he says.

The most frequent issue that Suresite is alerted to is when a tank gauge has detected water in the tank. "Ninety per cent of the time, this is due to the probe being disturbed during fuel delivery, with the reading reverting to normal once the delivery has ended. The 10% of cases that don't clear after delivery finishes are usually due to diesel bug contamination causing the probe to stick, so it can't return to zero. The difficulty comes in knowing which occurrences are simply stuck floats and which are real events."

The Suresite team can advise on the scenario as a whole and work with the site on the best course of action. They can make use of data-driven alerts alongside tank gauge alarms so they can set centralised triggers requested by the customer to detect issues as early as possible.

"Alongside this, forecourt customers are also facing issues relating to faulty valves, which can cause fuel lines to drain back into the underground storage tanks (line-drain-back)," says Barker. "While this fuel isn't lost to ground, it does place extra strain on the pumps as the line has to be re-primed on every transaction. Recently we identified 'line-drain-back' within hours at one of the sites we monitor. We found that a stone was blocking the under-pump valve. If this had been left undiagnosed, it would have led to eventual meter failure."

Issues within tanks and pipework that are allowed to persist can result in sites needing costly repairs so are always best dealt with promptly, he explains.

Barker adds that thankfully catastrophic incidents involving thousands of litres of fuel going to ground are a rarity. "With advances in wet-stock monitoring, we are now looking to identify loss on a much smaller scale. Suresite streams data 24/7 from site so we can identify unusual occurrences in real time. This, accompanied with our data-driven alerts means we are reporting issues as they occur, not the next day or even later."

tank gauge review

Barker continues: "As part of our install process we do a review of the history of the tank gauge. At one site we found an interstitial space alarm and a data driven water alarm, soon followed by a rise in stock height and a water-level reading. We were able to notify the site and arranged for an engineer to attend as soon as possible. This allowed the site to save the fuel in the tank, and by closing the tank off, no customers' cars were contaminated with water or interstitial space liquid saving the site from potentially hefty repair bills and, of course, reputational damage."

With new-to-industry sites rarer than they used to be, Barker says Suresite is coming across more legacy equipment. "However last year's changes to the Blue Book plus a greater awareness of the need to protect the environment are all driving considerations for maintaining and upgrading older infrastructure. And advances in technology mean it is now easier for tanks to be relined with new skins and even bladder systems. With additional tank skins, interstitial monitoring can be introduced and linked to a modern wet-stock management system."

He says installing under-pump valves (UPVs) is the most straightforward and cost-effective method to save fuel going to ground. A site with UPVs monitored with real-time wet stock is environmentally and financially in a good place. Any issues can be detected quickly, and fuel losses will be minimal as the fuel will return to the tank."


Problems with single-skin tanks

Ray Blake, technical manager at the PRA, says 99.9% of the issues he hears about relating to tanks and pipework are concerned with single-skin steel tanks and/or pipework that are still in use on sites.
"These older installations remain in use at sites where redevelopment or renewal hasn't been considered justified or viable. The reality is that the operators of these sites run the risk of either leaks into the ground that hopefully don't find their way to either voids where explosive atmospheres can form with the potential of harming people, or to water courses or sources, causing contamination and harm to the environment. Or leaks of water into the fuelling system that, if not discovered immediately, have reputational and financial consequences when customers' cars are filled with water."
He says that at some point single-skin steel will corrode and allow fuel to escape or water to enter, and it is impossible to predict when this will occur.
"There is evidence that the bio elements being added to fuel have, in some cases. accelerated the failures through internal corrosion of both tanks and pipework, and it is practically impossible to know the external condition of below-ground tanks and pipework.
"My advice to forecourt operators with single-skin steel installation is to ensure that they have correctly assessed the risks associated with it leaking. Also, to consider the impact of ground contamination to their site, as I know of sites that have become unsaleable due to the cost of decontamination."


OPW comes up with solutions

These are the most common problems with tanks and pipework that OPW comes across:
Problem: Water ingress into sumps.
Solution: Install high-quality products that will not deteriorate over time (eg Fibrelite GRP composite sumps and Fibrelite pipe and cable entry seal kits). Vacuum test sumps during installation and on completion of the install. Perform periodic visual checks post-installation in line with the manufacturer's recommendations.
Problem: Installation time is too long.
Solution: Installer training and design of products so they are installer friendly. This means features such as: more room to work (in the case of sumps) or a minimal number of welds (in pipework).
Problem: Steel pipe weight, corrosion and, installation time.
Solution: Lightweight plastic piping, eg Petro Systems Management (Ireland), ALFA LEVL GRUP (Russia) and VSE DLA AZS (Russia) have recently switched from installing steel piping to plastic KPS piping for all new installations.
Problem: Metal manhole cover manual handling risks.
Solution: Lightweight GRP composite manhole covers to reduce potential manual handling issues.
Problem: Metal manhole cover skid risks when wet.
Solution: Fibrelite GRP composite covers that have a special anti-skid surface.
Problem: Corrosion of metal sumps and pipework.
Solution: Highly-engineered GRP composite and plastic products.


As the Government is urged to publish its plans for E10 by the All Party Parliamentary Group (APPG) for British Bioethanol, would you welcome the introduction of E10 as the right next step in cutting automotive carbon emissions?