Page 17 - Updated SuDS Design & Evaluation Guide-Newham V3 Spreads

Overview 3.3 Consequences of piped drainage Limited pipe capacity, Trees and plants are at risk Overview

■
Recharge of groundwater and aquifers is
Piped drainage is designed to convey water
prevented, and the natural ‘baseflow’ of
away from developments as quickly as
water through the ground to
possible, and has become the default way to
of drought, due to lack of
manage rainfall across the developed world.
can cause local
However, this is at a cost to the environment ■ watercourses is lost. as well as blockage, rainwater.
and developments themselves. ‘Flashy’ flows from urban areas can cause flooding
erosion of watercourses.
The disadvantages of traditional piped ■ Trees and plants in urban areas are at
drainage are now becoming clear:
greater risk from drought stress, due to
■ Quickly carrying rainwater away from lack of access to rainwater.

where it falls can increase the risk of ■ Wildlife is often trapped and killed by
flooding elsewhere.
conventional drainage structures.
■ Limited pipe and network capacity, as well
as blockage, can cause local flooding as
water cannot get into the system.

■ Pollution from roofs, roads and car parks
is washed into the sewer when it rains,
contaminating streams, rivers and the sea

and killing wildlife.
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Foul water misconnections to surface water Pollution from roads and car parks is often ‘Flashy’ flows can
pipes result in polluted waterways at Glenbrook, visible - fuels, oil, heavy metals, tyre dust and cause erosion of
Enfield where sewage fungus is evident. silt all get washed into drainage systems. watercourses

Pollution can be
washed into
streams, rivers
and the sea.
Recharge of Hydrocarbons and
Quick conveyance of groundwater and tyre crumb are
rainwater from site can aquifers is prevented, examples.
increase the risk of and ‘baseflows’ to
flooding elsewhere. watercourses are lost.

Conventional drainage results in high rates and
increased amounts of runoff reaching streams
and rivers. Pollution from urban surfaces is also
washed into watercourses.

London Borough of Newham SuDS D & E Guide © 2020 McCloy Consulting & Robert Bray Associates London Borough of Newham SuDS D & E Guide © 2020 McCloy Consulting & Robert Bray Associates