GO isolated the 136ML Hope Valley EL170 tank and replaced the roof while maintaining supply. This was achieved by installing a new sleeve discharge valve in a valve chamber next to the existing sleeve discharge valve. GO identified a number of construction and operational risks associated with locating the valve underground and proposed an innovative solution to bring the valve above ground inside a soundproof building. This solution minimised the cost of excavating rock and provided a safe working environment for operators. The project included tie-ins to the existing buried MSCL pipework and the upgrade of an existing Hydraulically Operated Control Valve (HOCV) station, replacing existing pipework, pressure control valves and electrical and control systems.