LANDSCAPING SERVICES
Finally, two flow control chambers
on outlets from the basins protect
the combined sewer. Thus, rainfall
remains within the SuDS landscape
until storms have passed and the
sewer can deal with water again.
Winner of Winners
Recent Research
The importance of this was
highlighted in a 2019 report by the
Greater London Authority which
pointed out that pollution from
vehicles (including electric) is being
washed off impermeable surfaces
into dedicated ‘surface water’
sewers (which do not flow to sewage
treatment plants), then affecting
watercourses and rivers. Of course,
gulleys and piped drainage do not
remove pollution or attenuate water
flows.
Issues such as this have already
been recognised by changes to
planning ‘Permitted Development’
rules for new or replacement paving
around existing homes and various
non-domestic buildings. Before
these changes, paving anywhere
in a garden or within various
non-residential properties, using
any materials, was considered to
be ‘permitted development’. But
these rights have been taken away
unless permeable paving or other
permeable solutions within the
property are used.
Otherwise planning permission is
required for new or replacement
paving which is not SuDS compliant.
With national and, increasingly, local
planning policies encouraging or
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requiring SuDS, such applications
may well be rejected. For example,
the Draft London Plan says that:
‘Development proposals for
impermeable paving should be
refused where appropriate, including
on small surfaces such as front
gardens and driveways’. This stance
is supported by the 2019 National
Planning Policy Framework.
Exemplary Paving
An award-winning, exemplary
landscape and SuDS scheme, Bridget
Joyce Square in White City, London,
demonstrates the multifunctional
benefits of retrofitting permeable
paving in place of conventional
surfaces – not only on adopted
streets (as here) but also drives,
parking and other external areas. Its
design, by Robert Bray Associates,
introduces the innovative concept
of concrete block permeable
paving as a thin overlay for existing
streets, removing rainwater straight
from the surface without gulleys
and providing attenuation and
treatment before discharging to
adjacent, well-planted basins.
The concrete block permeable
paving overlay simply replaces
a tarmac road surface over the
original road base. The same blocks
and 2-6mm grit bedding layer and
jointing material as used in CBPP
generally are here installed over a
geo-composite conveyance sheet
that transports water horizontally,
on an impermeable membrane
covering the road base. Water is
attenuated and treated within the
paving, then released horizontally
via the stainless-steel letterbox slots
into the planted basins.
The scheme won ‘Winner of
Winners’ (the President’s Award)
as well as Winner of the ‘Adding
Value through Landscape’ category
at the 2017 Landscape Institute
Awards, and also an ICE London
Civil Engineering Award in 2016.
But most importantly, it has been
enthusiastically welcomed by
local residents, as recognised by a
Sustrans community survey.
A case study on the project can be
downloaded from www.paving.
org.uk. Here, you will also find
Interpave’s essential document
– ‘Design and Construction
of Concrete Block Permeable
Pavements’ Edition 7. This guidance
aims to ensure that CBPP delivers
predictable, robust solutions and
to minimise cost, maintenance
and adoption issues. Another new
Interpave guidance document,
‘Detailing Permeable Paving & SuDS
with Precast Concrete Products’, is
also available demonstrating how
precast concrete paving products
from Interpave manufacturer
members play important roles
in SuDS ranging from complete
permeable pavements to standard
components helping other SuDS
techniques work more effectively.
This document brings together
a variety of construction details,
demonstrating best practice to make
SuDS robust and durable over the
long-term.
www.paving.org.uk
www.landud.co.uk
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