Innovative SuDS tool for the Borough of Kensington and Chelsea

Innovative tool aids
SuDS planning
The Kensington and Chelsea Small Scale Sustainable Drainage Systems Tool
The impacts of climate change are affecting countries all over the world, with more
extreme weather causing droughts, increasing rainfall and flooding. Effective water
management is crucial to ensure the supply of clean water, safe disposal of waste
water and efficient surface water drainage to reduce the risk of flooding.
In England and Wales the Flood and Water Management Act 2010 and Flood Risk
Management Regulations 2009, changed the way flooding issues are managed, and
required the setting of national standards for Sustainable Drainage Systems (SuDS).
Upper tier Local Authorities were given the role of Lead Local Flood Authorities (LLFAs),
responsible for delivering local flood risk management. Most new developments with
drainage implications will need to obtain SuDS approval from LLFAs and therefore
meet the national standards for SuDS. This will be a separate process to obtaining
planning permission but will also be compulsory for particular developments.
Assessing the potential impact of new developments on surface water drainage has
therefore become a key consideration for local authorities.
SuDS are the accepted standard for large scale developments on greenfield sites.
Designed to replicate natural drainage systems, SuDS collect, store and clean surplus
surface water, before releasing it slowly back into the environment. Developments
in towns and cities have as much need for surface water drainage, though may have
fewer options for SuDS features because of the urban environment.
The Royal Borough of Kensington and Chelsea wanted a decision support tool to help
them assess what types of SuDS were needed for specific sites to aid them in applying
their newly adopted flooding policy requiring SuDS in all developments. This tool
could potentially be used to meet the new duties regarding SuDS. Commissioned in
April 2011, Royal Haskoning has been working with their planning team to design and
build ‘The Kensington and Chelsea Small Scale Sustainable Drainage Systems Tool’.
Innovative tool aids
SuDS planning

“Royal Haskoning worked closely
with us to deliver a high standard,
creative and very innovative tool.
Their consultants were always
flexible and approachable, using
their considerable knowledge and
experience in this field to help
us define our requirements and
ensure they were met.”
Patricia Cuervo, Senior Planning Officer,
The Royal Borough of Kensington and
Chelsea
CLIENT > THE ROYAL BOROUGH OF KENSINGTON AND CHELSEA
Helena Wicks, Royal Haskoning’s project manager explains:
“Royal Haskoning has considerable previous experience
in sustainable drainage systems and is a nationally
acknowledged expert in the field. We consider SuDS
as an important aspect of delivering integrated water
management within the global aspirations of growth in a
changing climate. We have designed and delivered SuDS
into many developments, including the RTPI award winning
Lamb Drove development in Cambourne, Cambridgeshire,
which has been cited as best practice by CIRIA (http://www.
ciria.org.uk/suds/cs_lamb_drove.htm) and England’s Policy
Position Statement on Development and Flood Risk (PPS 25)
Practice Guide. We have also written various best practice
guides and publications on SuDS and their consideration
within developments.
site conditions, surface types and rainfall run-off rates. Other
factors which can affect the applicability of certain SuDS
measures such as whether the location is in a conservation
area or is a listed building are also recorded.
The tool uses all of this information in the calculations and
provides a report detailing the sizes and types of the most
appropriate SuDS features. The report also gives a range of
storage (attenuation) volumes depending on the specific
site considerations and constraints that could affect the
SuDS features. Best practice guidance is provided and the
user directed to sources of further information to help with
detailed designs. The aim is to frontload the process so
SuDS are fully integrated by developers in the design of the
scheme before the planning application is submitted.
1090-cs-w-0312-Small Scale SuDS Tool-V00
“Most of the applications for developments in this densely
populated area of London are on a small scale, but the
Borough planners were concerned that the cumulative effect
of the proposals could have a negative effect on the surface
water drainage network. “Our multi-disciplinary team of
hydrologists, engineers, GIS and IT experts worked closely
with the Kensington and Chelsea planning team, holding
external and internal workshops to confirm the scope and
agree the requirements. We decided that the best option
would be a Microsoft Access database which could be used
internally by the planners and provide separate reports for
each individual planning application.”
The tool helps calculate the effectiveness of proposed SuDS
designs for small scale developments, up to a maximum of
10 dwellings or 1,000m2 of non-residential property. It takes
the planner and the developer through a comprehensive list
of questions to establish the size and type of development,
Helena Wicks
T: +44 (0) 1444 476 656
E: h.wicks@royalhaskoning.com
Helena continues; “Our approach was very innovative
and creative, from developing the original brief with the
Kensington and Chelsea planning team to designing and
building the tool from scratch. One of our challenges was
that best practice in this area is still being researched and
developed, so we had to reflect that and give a range of
options based on current knowledge. We also consulted the
Environment Agency to ensure we were in line with their
guidance on SuDS on larger sites, and confirm they agreed
with the decision framework”.
A key feature of this ground-breaking tool is flexibility. As
the body of knowledge and experience in this field grows,
the tool can be amended simply by changing the underlying
parameters. It can also be readily adapted for other Local
Authorities,. The tool will help developers design the most
appropriate SuDS systems before applying for planning
permission.
Delivered at the beginning of 2012, this decision support
tool is now being successfully piloted by the Kensington and
Chelsea planning team.
www.royalhaskoning.co.uk