The main control room threshold is predicted to be breached from the 1:50 year event. At a 1:1000-year event all the surveyed substation critical equipment is predicted to be under water. It was proposed to use flood mitigation funding in RIIO-T1 to construct a new 275kV GIS substation to replace the existing 275kV AIS substation. GTDS were contracted by Siemens PLC to install a new 275kV 9 Bay Indoor GIS Substation. The Works included Project Management, SHEQ Management, Installation and Commissioning of New Primary Equipment, Protection and Control Panels etc.