In line with the requirements set out in National Planning Policy Guidance, EAS prepared a detailed surface water drainage design to manage a 1 in 100yr plus 40% Climate Change Storm Event whilst restricting flows to greenfield run-off rates. Permission from the Lead Local Flood Authority was gained for a controlled outfall into a nearby watercourse. The surface water drainage comprises oversized pipes which attenuate and convey surface water to an outfall chamber within which is a flow control device that restricts flows. The foul water drainage was designed to meet Building Regs Part H standards with outfall to an adopted foul water sewer within the site boundary. EAS gained permission from Thames Water for a new connection to this sewer.