FIRE Correspondent Dave Sloggett looks at the unique challenges faced by crews attending the Ocado warehouse fire in Andover
Fires, it can be said, have a life of their own. There is always a subtle difference between events even if on the surface they fit a previous pattern; each posing its own special set of problems. For members of the fire and rescue services, wherever they fight fires, one of the knacks of firefighting is to grasp early on the nature of those differences.
This was certainly true of the fire at the Ocado warehouse in Andover which was attended by Hampshire Fire and Rescue Service with crews also attending from nearby services, such as Dorset and Wilshire Fire and Rescue Service. On the surface this was a warehouse fire, not of itself a challenge. Underneath the surface, however, this was a very different challenge. One that was to require a great deal of dynamic risk assessment and innovation.
The initial issue, says Andy Bowers, the Deputy Chief of Hampshire Fire and Rescue Service, was “the sheer scale of the facility”. It occupied an area nearly the size of three football pitches. Once ablaze, videos posted by the public illustrated the challenge firefighters faced.
The images from the public make impressive footage and showed the hazards facing the firefighters attending the scene. The thick black smoke blowing over a vast area billowing up to several hundred feet saw the brigade warn residents in the area to close their windows.
By the time crews arrived the fire had started to spread rapidly throughout the facility. It was quickly established that there was no immediate threat to life of anyone trapped inside the building. This enabled firefighters to focus on the blaze rather than also have to think about possible evacuations of employees.
Drones that the brigade would normally use to help gain an airborne image of the situation to help develop their situational assessment were not immediately available. However, it is possible to speculate that the contribution from infra-red sensors on a drone trying to fly above the facility would have been hampered by up and down draughts caused by the heat flow from the facility. This lack of coverage was made up by the picture that was available from the ALPs on which cameras were located.
Within hours, Hampshire Fire and Rescue Service had declared it a major incident. At its peak over 300 firefighters were on the scene, four of whom were checked in to hospital for the effects of smoke inhalation. Thankfully all were quickly released from hospital.
“In time-elapsed videos they show an impressive array of small robots navigating a ‘railway’ grid the size of three football pitches laid out in front of them”
The warehouse facility is one of four such installations in the United Kingdom. These house all the necessities for daily life. For customers the drudgery of the weekly shop is now removed. Ocado is not a supermarket in the traditional sense. It is a warehouse from which customers pick their weekly or monthly shop. It is packaged and sent to their homes. The Andover facility was capable of handling up to 4,000 orders a day from customers across the south of England from a range of 10,000 products held in the warehouse.
Videos of the operations of the warehouse that are available online reveal what is unique about its operations. In time-elapsed videos they show an impressive array of small robots navigating a ‘railway’ grid the size of three football pitches laid out in front of them. The grid is the size of three football pitches and sits 17 metres above the ground on one of 17 mezzanine floors in the single storey building.
Using wheels mounted on each side of the robot they can move forwards and backwards along the grid turning left and right at mini-junctions to reach their destination. At any instance in time nearly 700 robots are on the move on the grid. While on the surface it looks chaotic, underneath the movement of the robots is carefully choreographed.
The movement of the robots on the grid is controlled by what is described by Ocado in their marketing literature as an ‘air traffic control system’. This is based on collision avoidance algorithms. When operating at top speed the robots can move at up to four metres per second.
The robots are powered by lithium batteries and communicate through a Wi-Fi system. When the power available from the battery is low the robots simply move to a rest spot where they recharge themselves. The images also reveal that the technology used is so novel that Ocado also makes money selling the system across the world to other major retailers.
The grid on which the robots move is itself on a mezzanine floor that is largely sealed from human access. Speaking about the incident Neil Odin, the Chief Fire Officer of Hampshire Fire and Rescue Service, noted that making “an effective firefighting strategy” was “very difficult”.
As firefighters tried to tackle the fire innovation was the watchword. Like those at incidents like Buncefield before them it was a question of trying a number of approaches to get to the seat of the blaze when the warehouse ‘furniture’ and operations inside the facility posed a hazard to entry and operations. Various parts of the toolkits available to firefighters were used including drilling holes in the fabric of the building to gain access to the fire and pouring water down from above the roof which at one point partially collapsed.
While the source of the fire is not yet clear, speculation surrounds it being associated with one of the robots; possibly one of the lithium batteries that power the robots as they move around the grid. It would be easy to think of one robot catching fire and then travelling along the grid spreading the fire across the floor to other nearby robots.
While measures to shut down the operations were quickly put into effect, that would have taken time allowing the fire to spread. In that intervening period, it is possible that the damage had already been done. The fire had taken hold before the crews arrived on scene at around 0245 on the first day of the incident.
Speaking after the incident Andy Bowers noted that Hampshire Fire and Rescue Service had visited the warehouse when it had been constructed to conduct a routine check and raised some concerns over their ability to fight a fire in the facility. Their concerns were fully vindicated despite, somewhat ironically, Ocado receiving an award for its sprinkler system in June 2018.
Fire Risk Assessment
One specific worry for the firefighters was a three-ton container, situated on the roof, that contained ammonia. It used a gravity feed system to pass the ammonia to the refrigeration units inside the warehouse which were vital to its business operations.
The ammonia tank, however, located as it was on the roof, presented an explosive risk. Nigel Cooper, from Hampshire Fire and Rescue Service, said: “The toxic chemicals involved were extremely volatile and flammable”. He added that “our main aim was to try and keep the fire away from those chemicals but unfortunately due to the complexities of the building and the ferocity of the fire they encroached slightly”.
Shrapnel from the tank could have injured people nearby and the ammonia might have also spread as a cloud to nearby buildings causing breathing difficulties for people exposed to the gas. As a result, a 500 metre cordon was implemented and nearly 100 local people were evacuated to temporary accommodation in a hotel and a nearby school. Had the ammonia tank exploded the story might well have had a very different outcome.
Given the sheer scale of the fire it is remarkable that no one was injured. One metric quoted by Andy Bowers noted that over 300 BA units were exhausted during the operation. It is a massive tribute to the methodical way in which Hampshire Fire and Rescue Service and their colleagues from other brigades went about tacking the fire that saw it was brought under control so quickly.
While four firefighters were treated in hospital for suspected exposure to smoke all, thankfully, were quickly discharged. In such situations it is easy for people to forget that some situations have very different outcomes as events at a warehouse fire in Atherton-on-Stour in November 2007 showed.
It is clear this was a case of a difficult and challenging job that had been dealt with in a highly professional manner. While lessons will be learnt the underlying axiom that every fire is different and presents its own unique challenges will remain.