Hillingdon SuDS Design & Evaluation Guide

Raingardens
The raingarden concept was pioneered in
Prince George’s County, Maryland, USA in
1990 when small stormwater basins were
proposed for individual houses to replace
larger regional stormwater ponds.
Raingardens are designed to collect and
manage reasonably clean water from roofs
and low risk drives and pathways, has been
used where community or private care is
available to maintain these potentially
attractive site features.
Key aspects of raingarden design include:
1. gentle side slopes with water collected at
the surface
2. a free-draining soil, sometimes with an
underdrain to avoid permanent wetness
3. a minimum of 450mm improved topsoil
with up to 20% course compost
4. garden plants that can tolerate occasional
submersion and wet soil – this includes
most garden plants other than those
particularly adapted to dry conditions
5. an overflow in case of heavy rain or
impeded drainage.
Detailed Design
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London Borough of Hillingdon SuDS D & E Guide
© 2018 McCloy Consulting & Robert Bray Associates