When the explosion ripped through the block of flats at Redwood Grove, in Bedford, on Monday morning, it brought carnage to the south Midlands. The force of the blast reverberated through the town, and witnesses described the horrifying inferno that followed. Some jumped for their lives from the blaze. At least one person died inside, and firefighters expect to find more bodies in the blackened wreckage.
But the tragedy at Redwood Grove was neither the result of an airstrike, nor a bomb. Rather, Bedfordshire Fire and Rescue Service pinned the blast on a “major gas explosion” – a devastating reminder of the potentially destructive power of the methane used in millions of homes, up and down the country, whether in cannisters or fed in directly by corroding pipes that are now almost a century old.
But this is no one-off catastrophe. According to the Health and Safety Executive (HSE), there were 12 deaths and 178 injuries from gas explosions and fires in the five years to 2021.
It was the same story a week ago, in Kingstanding, in suburban Birmingham. There, cars were peppered with shrapnel, and a lamppost was levelled. Five houses were damaged so badly that more than 20 residents were not allowed to return. And in the middle of it all, a gaping hole had been clawed out of the terrace, a void belonging to 79-year-old Doreen Rees-Bibb. She lost her life in the fireball that engulfed her property. Another man is still fighting to survive, having been pulled to safety by neighbours.
No wonder Cadent, the gas network, was quick to confirm that, in the Kingstanding case, the mains and supply system were not to blame. The same could not be said about the carnage that engulfed Susan Shepherd and her Jack Russell, Milo, five years ago at their house in Sunderland. The pre-war steel service pipe that ran from the gas main in the street, under her garden and to her meter, had corroded. Methane seeped upwards, filling the wall cavities in her house, mixing with the air in precisely the right proportion to become a cocktail waiting for a detonator. When Shepherd opened her fridge one August morning, the internal light switching on proved spark enough. Once again, a house simply disappeared. Shepherd was only saved because her fridge landed on top of her and shielded her from the collapsing rubble.
Yet when the 40-year-old, whose daughter had thankfully not been in the house at the time, brought a personal injury claim against Northern Gas Networks, responsible for the pipes to her home, she lost. Disconcertingly, one of the reasons that the judge cleared Northern Gas last month was that – given the size and age of Britain’s gas delivery network – it’s just not possible to catch every potential time-bomb.
“The mechanism by which this explosion occurred, namely the leakage of gas due to a corroded pipe, is by no means an uncommon phenomenon,” the judge noted. The idea of excavating service pipes to see if they were corroded was just not “practicable”.
According to Stephen Walsh, a chartered engineer who has worked on many gas explosions and served as an expert witness, the problem is simple to diagnose but desperately difficult and expensive to remedy.
“The underground pipework has been there a long time,” he says, “and it’s corroding.” Though it’s hard to know for sure, he estimates that around “100,000km” of iron gas mains was laid in Britain. These are now the subject of a nationwide programme that aims to replace them all by 2032, with more resilient plastic pipes. “But there’s still tens of thousands of kilometres to go,” says Walsh.
And even when mains pipes are being replaced, it’s not mandatory to upgrade service pipes at the same time. Yet leaks from old iron gas mains, further from houses, tend to be less ruinous than those from the steel service pipes. “Gas from the mains can dissipate into the atmosphere,” says Walsh. “Whereas [with service pipes], the gas seeps up, and if it gets trapped anywhere in a room or wall cavity, that has the potential to cause an explosion.
“It’s only when a house is demolished that people take notice,” he adds. “But there are accidents occurring throughout the year. Most of them aren’t that serious, but there are fatalities.” In 2016, the HSE reported that there were “approximately eight to 10 million steel service pipes taking gas from mains to consumers’ premises” and that it was impossible for the gas companies to “establish and monitor the condition of all of the steel service pipes within their networks”.
“Life’s a lottery, and this is one of those tickets,” says Walsh. “You hope you’re not a winner.”
One of the unlucky ones was Stephen Mackenzie. In November 1985, he was sent home from school after lunch. He found his mother watching the news on television. There had been a huge explosion. “My Uncle John’s house had gone, [Aunt] Gina, [their son] Iain, and newborn baby Debbie. I never got to meet her. They were all killed. The nice lady upstairs – her husband was blown through the living-room window. It reduced the place to rubble.”
Even today, Mackenzie is still coming to terms with it. “We think a gas leak ran up the service pipe into the building,” he tells me. “The problem is, we don’t know how good or bad the network is. But we do know it’s antiquated. Where are we getting the leaks? How big is the problem? How many near-miss events do we have?”
Mackenzie followed his father into the plumbing trade, before his family history inspired him to become a gas safety specialist and finally a combustion engineer; one thing he does know is that when things goes wrong, gas “goes off like a bomb”.
Not that all explosions are down to network faults. Many, like the Birmingham blast, are a result of a problem with pipework, canisters or appliances inside rather than outside the house – and for these, homeowners are responsible. Several thousands of dangerous fittings are reported to the HSE every year.
Homeowners, Walsh explains, can often tell quite easily if old steel service pipes to their houses have been replaced with modern plastic ones. Once replaced, the gas meter is usually relocated to the outside of the building.
On top of this, even when there is a leak, an explosion isn’t guaranteed. Gas needs to mix with air to become explosive: too much gas and there is not enough oxygen for a blast to occur. Danger occurs when the proportion of gas to air is between 5 and 15 per cent. “Too much gas, nothing will happen. Too little gas, nothing will happen,” says Walsh, who adds that while the powerful smell of a gas build-up is usually instantly recognisable, residents are sometimes unaware of it if the leak is slow. “You get to the point that the gas is all around you – you get used to it,” he adds.
“Health and Safety acknowledge that there is a risk… explosions can occur. Something’s got to be done.”
CLARIFICATION: This article has been amended to make clear that gas explosions can occur both through canisters as well as mains gas fed directly in to houses. It has been confirmed that the Bedford explosion, referred to in the article, was not caused by mains gas.