INF 4: Drainage

1. Development proposals are expected to incorporate:
2. Drainage strategies for development must strictly adhere to the approach of the drainage hierarchy:
3. a.an integrated approach to the management of flood risk;
4. b.a strategy for surface water, groundwater and foul drainage;
5. c.management and maintenance plans incorporating any on-site and adjacent watercourses where riparian rights exist;
6. d.flood resilient design that assesses and responds to the existing hydrological characteristics of a site; and
7. e.-surface water drainage (SuDS) strategies for both minor and major schemes regardless of flood risk designation.
8. Priority 1: Collect for non-potable use – rainwater harvesting (e.g. toilet flushing, irrigation).
9. Priority 2: Control at source:
10. i.infiltration, green roofs, run-off to grass or verge, water butts, and permeable layers.
11. ii.on site SuDS treatment with other sustainable drainage system techniques – collection for infiltration and detention.
12. iii.Local SuDS treatment with other sustainable drainage system techniques – collection away from site.
13. iv.Regional SuDS treatment with other sustainable drainage system techniques – collection in wetlands and balancing ponds.
14. Priority 3: Discharge to watercourses – including canals, streams, ditches or existing swales.
15. Priority 4: Discharge to surface water sewers.
16. Priority 5: Discharge to combined sewers.
3. Solutions at lower levels of the hierarchy must only be considered when higher level solutions are demonstrably not possible or suitable. Where more than one