The risk of using resin-generated (RG) foam to fill redundant tanks in the concourses lies primarily in the assumption that it is risk-free.

Resin-generated foam, in its many forms, RG22, RG8, and RG30, is now widely used at fuel sites everywhere. RG30 is used to line fuel tanks for added safety and protection against contamination. The RG8 is used to fill degassed tanks very temporarily, as it is claimed that it can be completely decomposed with water. RG22 is the most prevalent as it is widely used for “permanent” tank filling.

The RG22 was first developed at a time when the solid fill material of choice was a 20: 1 sand / cement slurry. To successfully fill each part of the tank with this, contractors had to open the top of the tank, pour the grout and shake it; otherwise it would settle as a cone with space around it. Sometimes part of the esplanade had to be excavated if the manhole was in the wrong position.

The advantages of the RG22 were that it was said to be safe, environmentally friendly and could be pumped through an outlet pipe or flange on the manhole cover. This made it a huge favorite among oil officials and oil companies, some of which began to insist on its use.

It was also cheaper than grout and much lighter, which meant the final excavation of the tank was said to be easier and less expensive.

The introduction of foam concrete has eroded some of these advantages, as it is much lighter than its predecessor and has similar flow properties. This means that for most fuel site uses, there is now a viable alternative to RG22 that meets the requirements of oil companies and oil officials.

The main reason we need an alternative to RG foam is that it contains formaldehyde, a probable human carcinogen. In 2002, formaldehyde was included in the 11th edition of the US Carcinogens Report, Compiled by the US Department of Health and Human Services, the Public Health Service, and the National Toxicology Program; something that only has moral power in the UK and the EU.

In Canada, urea-formaldehyde foam, which also uses formaldehyde as a curing aid, was used to insulate houses, particularly wood-frame houses, but is now banned by the Canadian government after occupants complained of dripping. nasal and eye pain.

Because formaldehyde is used as a curing agent, while R22 must be handled carefully at all times, the greatest health risk does not occur when foam is pumped into tanks in its liquid state, but rather when it is fills the so-called ‘permanently’ tanks must be excavated and removed to allow a site to be dismantled and used for some other purpose.

The concerns are twofold: handling the foam itself and exposure to formaldehyde gas that is given off when tanks are dug and cut for disposal.

Due to its purported properties, we were just as interested in using RG22 as anyone else when it first appeared. Our doubts began when we started digging tanks that had been filled with the foam and discovered how difficult and expensive it was to dispose of them.

We found that RG22 can shrink, allowing air to flow back into the tank, reducing the safety effects of RG22 and accelerating corrosion. Later we also found out that it gave formaldehyde gas a place to meet.

We have excavated tanks less than three months after they have been filled with RG22 and the foam had already reduced considerably. On the other hand, we have excavated tanks that were filled with RG22 two years earlier and found that some of the foam was still in a liquid state.

When our people opened the tanks, they found that the fumes were often overwhelming and anyone who was unlucky enough to touch things got a nasty and uncomfortable rash as a reward. All of our people now wear a full suit and breathing apparatus when it comes to RG22. “

The lightness of the foam was supposed to make digging easier, allowing the tank containing the foam to be lifted directly off the ground and placed in the back of a truck. Unfortunately, we found that there are only one or two disposal sites that will accept tanks with RG22 still inside. Even then, they will only accept small tanks, and only when they can be placed in a deep part of the landfill.

We will only attempt the all-in-one approach when our customer insists as we prefer the greener approach of shipping the tank metal for recycling. This means that once it has been removed from the ground, the excavated tank must be cut, and the metal is taken to one site and the RG22 to another, usually a hazardous waste site.

We are not the only ones with concerns, another company in our industry told us: “RG foam is fine if the tank is never going to be opened again, the problem is that these days, eventually, many tanks will be needed. Removed , if the site will be sold for development.

“My concern is that when we open the tanks there is a very pungent formaldehyde smell and often a sore throat and eyes.

“Now we use a different technique where we try to use heavy machinery to open the tanks, keeping personnel away from the excavation.

“It seems that the problem lies in the fact that during curing the foam emits a considerable amount of formaldehyde gas, which is trapped in the tank, to be released only when it is opened.

“Our workforce also initially noticed some irritation through exposure to the foam and, in fact, the manufacturers’ data sheet says it is a ‘mild irritant’.”

This company believes that the main problem is that, in addition to being an irritant, the material is light and friable, so, if precautions are not taken, it can get under clothing or even be inhaled.

“However,” says the company, “this part of the problem can be solved if contractors are properly warned. Like any other risk, they can deal with it, if they know exactly what they are dealing with, by elimination, in the first place.” example and, when not possible, control techniques such as the use of protective clothing, gloves, masks, eye protection, etc.

“A bigger problem is that fuel sites undergoing decommissioning are typically bounded by roads and pavements, often in built-up areas, so there is a danger that light friable foam could easily slip off the site. These days We do not remove these foams on a windy day.

“However, as I said, the problems associated with the foam itself can be solved with a few simple precautions, our real concern is the formaldehyde gas that is given off when the tanks are shut off, as it should be when a site is decommissioned. .. “

Experience has shown us that air pockets occur, where gas tends to concentrate, leading to a gas explosion being released when these pockets rupture.

Proximity is the real problem. Once the formaldehyde gas is vented to the atmosphere, it will be distributed to a harmless level, but if it is near the tank when it is cut off, it is more of a concern.

The environmental and personal monitoring was carried out by a company in our sector, observing the level of formaldehyde gas concentration in the fuel sites that are dismantled when the tanks are opened.

In one of these tests, formaldehyde sensors were placed at four strategic points on the site. Three produced results below the recommended level of two parts per million, but the closest sensor, located 3 m from the tank, registered 2.07 parts per million, which exceeds the UK’s Workplace Exposure Limits (WEL). 2.0 parts per million, currently listed in HSE Publication EH40 / 2005 Workplace Exposure Limits.

This indicates that steps must be taken to protect anyone approaching that distance.

We also believe that the two parts per million limit itself needs examination as, in my opinion, there is no real evidence for this level, one way or another. Much more research is needed.

The message is to be aware of the risks and take the proper precautions.

The main problem is the respiratory system and the eyes, so we use a helmet, with a visor and an assisted respirator.

His message to oil companies and officials is not to be seduced by the supposed benefits of RG foam, to look for where it is appropriate to use it.

RG foams have their place in the mix, they should not be seen as the first resort.

It may be a bit more economical to use RG22 to fill the tanks first, but any savings are outweighed by the additional disposal costs and the precautions that must be taken.

Hazard management hierarchy.

1. Delete

If the work is dangerous, is it really necessary to do it?

2. Substitute

If the work is really necessary, then the hazardous material can be substituted for something more benign, such as grout, foam concrete, or polyurethane, which is now sold as a substitute in the US, but not here yet.

3. Change working methods

Use more machinery to reduce direct contact. Pay more attention to the weather on digging days.

4. Control

Increased use of personal protective equipment (PPE) and greater attention to on-site containment.