Page 28 - Enfield SuDS DESIGN & EVALUATION
P. 28
Due to the high variability in ground Local LPA and Stakeholder Engagement
Local SuDS requirements
conditions it is recommended to carry out a
ground investigation for all development to Enfield Council provide pre-application
establish the potential for infiltration. There advice for developments, and can provide a
may be areas with permeable geology that pre-application report with information and
may not be suitable for full infiltration, such maps on topography, geology, flood risk,
as areas with high risk of contaminated land. greenfield runoff rates and recommendations
These areas pose high risk of mobilisation of for SuDS measures. In addition to the LLFA,
pollutants that could potentially contaminate there are a number of stakeholders that must
groundwater if full infiltration were to be be consulted in terms of flood risk, obtaining
used. They are mainly located in the Lee discharge consents and building in proximity
Valley where there has been extensive to structures and watercourses. These are:
industrial activity historically. Above ground ■ Environment Agency are to be consulted
SuDS measures can still be used in areas of if the development is with 8m of a main
contaminated ground provided that an river, falls within Flood Zone 2 or 3, is
impermeable liner is used to ensure there is within a Source Protection Zone, or on the
no risk to groundwater. discharge of surface water to a main river
Local SuDS specific requirements ■ Enfield Council’s Structures and
Watercourses team are to be consulted if
Enfield Council’s planning policies are the site is within 4m of an ordinary
contained in the Development Management watercourse, culvert or structure, falls
Document which forms part of the Local
23 Plan. The below policies refer to flood risk within an area subject to surface water
and surface water management: flood risk, or on the discharge of surface
water to an ordinary watercourse
■ DMD 59 – Avoiding and reducing flood ■
risk (page 93) Thames Water are to be consulted on
discharges/connections to surface water
■ DMD 60 – Assessing flood risk (page 94) sewers, or if the site is in proximity to a
Thames Water asset such as the New
■ DMD 61 – Managing surface water (page
River
95)
■ The Canal and River Trust must be
■ DMD 62 – Flood control mitigation consulted on discharge to the Lee
measures (page 97)
Navigation
■ DMD 63 – Protection and improvement of Adoption of SuDS
watercourses and flood defences (page
98) Enfield Council will consider Sustainable
Drainage features for adoption. Consultation
In summary, DMD Policy 61 requires all major
developments to achieve greenfield run off with the Council is advised if the developer
rates (for 1 in 1 year and 1 in 100 year events). wants to seek adoption of SuDS measures
Enfield Council SuDS D & E Guide © 2018 McCloy Consulting & Robert Bray Associates
