Issue link: https://fhpublishing.uberflip.com/i/796215
NETWORK / 19 / MARCH 2017 Storm DeSmonD: the factS • Before 5 December, Cumbria had already experienced exceptional rainfall, leaving the ground waterlogged and the floodplain upstream of Lancaster flooded. • The Met Office expected between 150 and 200mm of rain. • At the storm's peak, the Environment Agency recorded the highest flow of any river ever recorded in England – 1,742 cubic metres of water per second. • High-capacity pumps and extra protection were brought in to defend Lancaster substation but these were unsuccessful. • At 10:39 ENW made the decision to switch off the substation. • 22,000 customers were reconnected to mobile generator supplies by the following day (Sunday). • By noon on Sunday the waters had receded and the substation had been pumped out. • Grid transformer 1 was restored at 4.28am on Monday 7, and power was restored to almost all households by 3.30pm. • The connection point between conduc- tors – a common 33kV busbar – failed catastrophically because of water ingress. • ENW reconfigured the power supply so Grid Transformer 1 fed the Spring Garden Street and Burrow Beck sub- stations as well as central Lancaster. • Restoration was largely complete by 7.18pm on Tuesday December 8. switchgear – which contained fuses rated at five and six amps – should have been safe, but the floodwaters of Storm Desmond went higher, visibly scarring the old stone wall running along the roads of Lancaster with a grimy tide mark reaching almost hip height on the average man. Once the substation was flooded, there was no saving the power and the lights went out. Further north, Carlisle substation was also swamped by rising water when the river burst, but here the third and final transformer was saved at the last minute by pressing every reset button available, Deehan recalls. The water was rising so quickly that the inspection crew decided to evacuate. They faced being stranded because the only access route was flooding behind them. The reason Carlisle could be saved and Lancaster could not was simple: "Bigger buckets," Deehan says. "We were lucky, we lost two grid transformers. The third one, I have never seen the temperature go up in real time, it reached 110°C. We hit every reset for all we were worth and the cooling came on." Transformers are fairly water resistant, but the investment plan for the site includes liˆing two of the transformers three metres off the ground to protect them. The real vulnerability in a substation is the electrical fuses in the control panels. Once wet these must be dried, cleaned to prevent corrosion and tested before power is switched back on. "It's not just a case of plugging them in and connecting the wires up," Deehan says, "the testing that goes on behind that, it all needs to be done in a controlled manner. But first what you've got to do is get them dry and clean because a lot of the flood water is contaminated – it's not nice clean shiny water," he explains. Ideally, ENW's engineers would like several days to complete this task, ensuring all the equipment is properly dried, but with customers waiting the whole process can be completed in about 30 hours. "The answer really is don't get them wet in the first place. This equipment is not designed to be immersed in water," says Deehan. The real difficulty in getting a substation back up and running is not dealing with the electrical equipment itself. "Once we get on site, this is our environment, we know what we are doing. It's getting to site, that's the thing you have to fight, and that's beyond our control." ENW does not have a unique solution to the problem of flooded roads. "Normally you can get close to site, but this time you couldn't get within ten miles of site without trying four or five different routes because all the normal routes were blocked. It was uncharted what happened that day." Deehan is not shy about laying a great deal of the credit for its fast response at the feet of the emergency services. "The multi- agency support that we got throughout Storm Desmond was absolutely fantastic – the police, fire and rescue – everybody who could possibly help did." Even International Rescue, an organisation of willing volunteers ready to