Page 99 - Hillingdon SuDS DESIGN & EVALUATION

9.6.1 Design flexibility

A framework of three approaches which
deliver variable outflow rates (Approach 1)

are explored by this guide. These approaches
are intended to inspire the designer to think Detailed Design
about the possibilities that exist for
integrating storage as part of the
development rather than defaulting to an
underground storage structure prior to
discharge from the site. They can be
summarised as follows:

Distributed storage components

■ distributed storage volumes into discreet
storage components such as raingardens,
swales, basins and permeable pavement
with the potential for different rainfall
depths being stored at each location.

Single, uniform storage components 94

■ store up to the 1 in 100 year rainfall in a
single storage component, such as a
permeable pavement or blue-green roof,
with openings sized to achieve the
variable outflow rates.

Single, tiered storage components

■ store up to the 1 in 100 year rainfall in a
single, tiered storage component, such as
a smaller basin used on a regular basis
within a more extensive basin for more
extreme rainfall events and openings sized
to achieve the variable outflow rates.

London Borough of Hillingdon SuDS D & E Guide © 2018 McCloy Consulting & Robert Bray Associates