8.2 Design principles for SuDS in Surrey

Specific designs will differ by location and will reflect the local context, site layout, local topography and geology. Detailed design guidance is available on the Surrey County Council SuDS Design Guidance website.

However, all planning and design of SuDS must:

• Be designed to accord with the Environment Agency (EA) long term flood risk assessment, Construction Industry Research and Information Association (CIRIA) guidance, Defra non-statutory technical standards and the appropriate District or Borough Local Plan;
• Manage surface run-off as close to the source as possible;
• Follow Surrey County Council’s sustainability hierarchy (see figure 8-2); and
• Consider the effects of climate change, such as increased rainfall intensity, in line with current Environment Agency and SCC guidance.

Figure 8-2: Sustainability Hierarchy for SuDS selection (Credit - SCC)

• SuDS must be designed with multifunctionality in mind from the start.
• They must follow the four SuDS objectives to enhance:
• Water quantity: to control the rate and volume of runoff, preserve the water cycle and reduce flood risk.
• Amenity: create and sustain better places for people, through the introduction of greenery and water features.
• Water quality: manage the quality of runoff and prevent pollution of watercourses.
• Biodiversity: to create and sustain better places for nature by including planting and habitat niches that respond to surrounding ecological conditions.