A 'LIVING' roof has been installed at the Stone Castle Centre, a multi-million-pound health facility currently being built for NHS Doncaster. Designed to boost the green credentials of the two-storey building, the mass of sedum plants act as sponges, soaking up rainwater instead of allowing it to flow into the mains drainage system. The 12m by 10m lawn is separated from the flat aluminium roof by layers of sand and rubber. Doug Eastwood, site manager for construction partner, Morgan Sindall, said: "Some of the rainwater landing on the building's aluminium roof will be harvested and channeled into a 2,000-litre tank, which will supply water to flush the building's six public toilets. In periods of low rainfall an external mains supply will automatically kick in if the tank gets low. Other rainwater run-off will be trapped in a huge tank and released into the mains drainage at a steady rate to prevent the drains becoming blocked during stormy weather." Costing £7m, the centre is on track to open next month, making it the eighth new 'mega surgery' to be built in the Doncaster area by Doncaster Community Solutions - a public/private sector partnership involving NHS Doncaster and Doncaster Council.