Detailed technical work has been completed in respect of drainage to understand how the site could be developed to ensure the current drainage regime is maintained and there is no risk of surface water flooding to existing or new residents of Uckfield
The development area to the east of the A22 is entirely within Flood Zone 1, in land defined as having a low risk of flooding from rivers or the sea.
Within the development area there are several small watercourses that flow through the site and into Shortbridge Stream via culverts beneath the A22. There are several flow paths that form in the woodland surrounding the watercourses during extreme storms but the EA maps show that risk of flooding outside of the woodland areas is very low from these sources.
There are no other risks of flooding identified within the site, including from groundwater, sewers, reservoirs and canals. There is no history of flooding identified within the site.”
The drainage strategy for the site has been carefully designed so that the flow of water within the Ancient Woodland ghylls are retained as per the existing situation. Surface water runoff from the proposed development would be restricted to the greenfield runoff rate, which mimics the existing runoff from the undeveloped site, so that flood risk is not increased off site. A series of detention basins would provide the required attenuation, prior to discharge into the ghylls.
A range of other Sustainable Drainage Systems (SuDS) are proposed within the site in addition to the basins, including swales, rain gardens, permeable paving, and rainwater harvesting. These would slow the flow of water, as well as providing treatment to remove potential pollutants and amenity and biodiversity benefits.
Some of the types of drainage features are shown below.