Following the damaging rains of 2007, the National Grid instigated a flood resilience programme to ensure that its substations are protected and remain operational during extreme flood events. We were commissioned to assess the flood risk for over 100 electricity substations, which together provide power to up to 500,000 people. Where risks were judged to be intolerable, our engineers were tasked with designing effective flood resilience measures.
Using detailed hydrological and hydraulic modelling, we assessed the risk to substations from heavy rainfall, river and tidal flooding, and other sources including flooding from sewers and drains and reservoir failure. Our solutions aimed to protect each substation through whole-site protection, such as flood walls and/or earth bunds; localised protection, such as building barriers around equipment; raising or moving critical equipment; improvement of site drainage systems; installation of pumps; and drainage diversions.
Many National Grid substations are now protected against extreme flooding, including 1:1000 year flood events. The remainder will be made resilient by the end of the programme in 2022. The programme will help to safeguard power supplies to critical assets in all infrastructure sectors – such as water, transportation, communication, and health services – maintaining the provision of essential services to the public and preventing disruption to the economy.