Cost-effective drainage

While we keenly follow new technological developments in structural and geotechnical design, we will use simple traditional designs where they are beneficial to our clients.


A housing developer commissioned our specialist subsidiary Robson Liddle to review an existing outline drainage design for a new site at a former Royal Navy Stores at Topsham, Exeter. The proposal they had been given by their initial designers was for a sustainable urban drainage system (SUDS), forming a rainwater catchment void 2.5m underground. This was below the water table, and flotation issue meant that the hi-tech plastic 'crates' forming the void would need to be weighed down with concrete.


Working as a collaborative team with the developer, we looked at other solutions. Our proposal was to replace the SUDS system by forming the void with a simple cast in-situ concrete 'box' structure. Its natural weight negated the flotation problem, and its simplicity saved 10% from that part of the project budget.