Page 137 - Updated SuDS Design & Evaluation Guide-Newham V3 Spreads

P. 137

Detailed Design Channels and rills Filter strips 3. Free draining soils - a protective liner Detailed Design

Sett Channels and rills keep rainwater at or
The hard edge from a pavement to a filter
strip is generally defined by a kerb. Filter
near the surface. This is important as it allows
should be situated at least 300mm below
water to flow directly into SuDS features
strips are effective at removing silt at source
clean sub-soil for an agreed distance
reducing cost, trip hazards and the
and will connect to SuDS feature such as a
offset from the pavement to prevent
inconvenience of deep structures in the
swale after a short distance.
pollution migrating through subsoils to
landscape.
groundwater.
1. Provision of a small drop across the edge
In some places a grated surface channel may
be more appropriate but the mesh size
off the pavement.
surface with limited potential for
should not be too small or the grating will be A planted rill at Bewdley of the kerb allows runoff to move freely 4. Clay soils - runoff will flow across the
infiltration negating the requirement for a
School Science Block.
prone to blockage. 2. The concrete haunch should be finished liner.
at minimum of 100mm below the surface
Collecting runoff from a road can be more to ensure good grass growth up to the
difficult where there is a path present and a
edge of the pavement.
flush kerb inlet or chute gully may be needed.

Use of pipes
Although SuDS are delivered without the
requirement for extensive piped networks,
short lengths of pipe can still be very useful

in providing connections under roads, A granite sett channel collecting and conveying
131 footpaths and other crossing points. Key runoff at Holland Park, London. 132

points to consider are as follows:

■ Short lengths of pipework should allow
direct rodding from one end of the pipe
to the other without the need for internal
chambers.

■ Inlets and outlets should be designed so
that they are not prone to blockage.
1
■ An exceedance flow path should be
Concrete pipe surround has been used here to
integrated into the development surface provide minimal cover for a driveway crossing at
above pipework to ensure that Devonshire Hill, Haringey. 2
unpredictable flows are directed SuDS
immediately after the crossing.
■ The depth of the downstream component concrete surround can be considered to 3

should not be artificially increased due to minimise cover - as used for driveway
a requirement for structural cover over crossings at the Devonshire Hill project 4
pipework. Different pipe materials or above.

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