On this project we were subconsultants to Structural Engineers David Dexter Associates. The project is a multi storey Firmdale hotel with two levels of basement built on the semi derelict site of a former multi storey car park very close to Piccadilly Circus.
Our first task was to understand the existing complex drainage network, which required extensive CCTV surveying of the ageing pipework in the basement of a part demolished car park. Having established existing flow patterns we have prepared options for the new drainage, taking into account the deeper basements proposed and the need to remove third party flows from the current system.
To minimise pumping costs and consequent carbon footprint, the system will maximise gravity foul and storm drainage, resorting to pumped systems only for sanitary fittings below the level of the local public sewers.
A partial green roof system reduces stormwater run-off and has allowed us to negotiate the discharge of pressure relief drainage from beneath the basement raft into the local Thames Water sewer network.