CONCRETE & STONEWORK
Key SuDS Technique
These multifunctional possibilities
are expanded further with concrete
block permeable paving (CBPP), a
uniquely flexible SuDS (sustainable
drainage systems) technique. It
provides an inherent drainage
system that requires no additional
land take for water storage,
treatment or conveyance, and
offers the same visual richness as
conventional block paving.
Its capability to attenuate
water flows during rainfall for
gradual discharge is optimised
by considering distinct storage
‘compartments’ of permeable paving
strategically deployed around a
development, each with a flow
control demonstrating compliance
to local authorities as part of the
SuDS design approval process. In
fact, it can also accept runoff from
other impermeable paving and
roofs, giving further savings.
Overall, whole-life-
costs were much
lower than those for
the conventional
piped drainage
system. The
Monitoring Report
noted capital cost
savings of £314
per home using
SuDS, with further
potential savings
available through
more holistic design,
as well as lower
maintenance costs.
Holistic Design
This is particularly interesting when
considering the extra water storage
provided within deeper CBPP
constructions needed to support
heavier traffic, as discussed earlier.
Here, a holistic design approach
combining trafficking and drainage
can maximise multifunctionality
and still deliver attractive hard
surfaces.
CBPP also addresses both flooding
and pollution issues by storing and
cleaning water runoff at source
avoiding drains surcharging and
downstream flooding. It removes
water-borne pollution and provides
a gradual flow of clean water at
the head of the ‘SuDS management
train’ enabling safe, open SuDS
features on the surface downstream
and enhancing landscape design and
biodiversity.
This technology also eliminates
pipework, gulleys and manholes,
and should therefore cost less than
conventional drainage and paving.
These savings are demonstrated at
the Lamb Drove SuDS Monitoring
project in Cambridgeshire, which
assesses various SuDS techniques,
including CBPP, in a management
train, compared with a conventional
piped drainage system nearby.
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A new Interpave case study on this
project has just been published,
alongside Interpave’s new guidance
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. It includes
the most recent CBPP techniques,
such as overlays to existing road
constructions and enhanced,
predictable water storage using flow
controls. Design procedures have
been comprehensively updated and
new, straightforward maintenance
guidance added.
Finally, it is worth remembering that
the key to attractive, durable, cost-
effective precast concrete paving
is to optimise its modular nature,
by dimensioning areas to minimise
cutting and combining compatible
products to avoid it. As with any
construction operation, detailing of
edges, insertions, level changes and
junctions within paving should not
just be left to site operatives but
resolved off-site by designers. With
precast concrete paving of all types,
well-established guidelines and case
studies are readily available from
Interpave’s information resource:
www.paving.org.uk
Detailing Guidelines
Another new Interpave guidance
document, ‘Detailing Permeable
Paving & SuDS with Precast Concrete
Products’, is also available. 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.
Interpave, The Old Rectory, Main
Street, Glenfield, Leicester LE3 8DG
Tel: 0116 232 5170
E-mail: [email protected]
Website: www.paving.org.uk
www.landud.co.uk
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