SuDS in London - a guide

6.3 Drainage
hierarchy
SuDS designs should generally be
developed according to the CIRIA process
diagram on the previous page. This process
may vary, depending on local conditions
When working in London, water should be
managed by using the following drainage
hierarchy, as described in the London Plan:
1. Intercept and store rainwater for later
use: examples of this include water tanks
and butts, or as well as abandoned and
repurposed subterranean pedestrian
passageways below urban roadways.
2. Use infiltration techniques, such as
permeable surfaces: these offer simple
and relatively low cost surface water
absorption capacity. Permeable surfaces
collect, store and release water at
different rates, depending on the sort of
soil present. Local geological makeup and
hydrology should take account of buried
infrastructure (such as that associated with
London Underground) to ensure chambers
do not become water conduits.
1. Disconnected downpipe to water butt
3. Attenuate rainwater in ponds, green
or blue roofs or open water features for
gradual release: ponds, linear wetlands
and basins can create attractive features
that provide ecological habitat as well as
amenity. There is also scope to incorporate
SuDS into green space alongside London’s
highways.
2. Grit jointed permeable paving
3. Attenuation in planted rill
129 6 Implementation