Page 41 - Updated SuDS Design & Evaluation Guide-Newham V3 Spreads

P. 41

Concept Design 7.4.6 Introducing sub-catchments When integrating SuDS into a development, A flow control generally defines the Concept Design drawings should identify Concept Design

Many drainage designs adopt an approach
sub-catchment boundaries with associated
downstream end of a sub-catchment, with
where all flows are taken to the lowest point
the site should be divided into sub-
storage and flow control locations
the flow control situated at the lowest
catchments to maximise treatment and
of the site and attenuated in a single location,
throughout the development.
topographical point within the sub-
often referred to as a ‘pipe-to-pond’ or ‘pipe
storage capacity.
catchment in locations that are accessible for
to box’ approach.
The sub-catchment boundary is usually
inspection and maintenance.
defined as the surface area which drains to a
The ‘pipe to pond’ approach can result in
unsightly, polluted and sometimes hazardous
considered as a mini-watershed.
pond or basin features that offer little
amenity or wildlife benefit. The ‘pipe to box’ particular flow control, and can be Flow control with
Flows are conveyed from one sub-catchment
approach results in below-ground structures to the next along one or more management contolled discharge
that provide no amenity or wildlife benefit at from one catchment to
trains, following the modified flow routes the next
all. All end of pipe solution may fill with silt determined early in the design process.
and generate management problems.
Each sub-catchment contributes flows to the C1
following sub-catchment or to an outfall.

C2
C3

35 36

Controlled flows are released from one sub-
catchment feature to the next, as here at Birchen
Coppice Primary School, Kidderminster.

Sub-catchments are generally defined by flow
controls. Flows are conveyed from one sub-
catchment to the next.

Design Note:
Integrating storage within sub-catchments, as part of site layout, greatly reduces the land
take requirement for attenuation, by exploiting the inherent storage capacity of individual
SuDS features.

36 37 38 39 40 41 42 43 44 45 46