Biobasins are designed essentially as a large filtration system for water running off the estate, before it enters waterways such as creeks and rivers. This is achieved by creating a catchment and filtering the water through several layers of filter sand and plants on top.

• Excavate each basin to correct size and depth

• Lay impermeable matting along base to prevent water loss

• Dig trenches and lay pipes for the water to flow down through the sand and then into storm water outlets

• Refill basin with sand (2 layers, 100mm transition layer followed by 600mm filter media) and plant through top layer of sand

• Coir fitted to batters for stabilisation and on basin floor to prevent wash and gouging in high flow areas

• Rock armour installed upstream to add in filtration and prevent gouging