Flood Risk Management in the Royal
Borough
The problem of flooding
Both the Royal Borough and the neighbouring borough of
Hammersmith & Fulham have experienced flooding incidents
over the last 20 years. The main reason for the flooding is
the inability of the Counters Creek, the Victorian sewer
system to cope with the amount of surface and foul water
entering the system during significant rainfall events.
However, there are other causes that can lead to
an increase in flooding:
- an increase in population with more development can
lead to an increase in foul water discharged
- an increase of impermeable surfaces as a result of actions
such as paving gardens and building more houses and roads. As
a result, rainfall does not soak away into the soil - it
drains directly into an already close to capacity sewer system
As a result, the Counters Creek sewer can
get overwhelmed during periods of heavy rainfall and can
surcharge back into the lower parts of properties (normally
basements) causing flooding with all distress and damage
that is associated with it.
Objectives and solutions
The Council is working in partnership with Thames Water to
reduce the risk of flooding. There are several solutions to the
problem which cannot be viewed in isolation, but various
objectives have to be integrated to achieve a successful
solution.
Increase the size of the existing Counters Creek
sewer
Thames Water is researching this through the Counters
Creek Sewer Alleviation Scheme.Thames Water will be
submitting a bid to Ofwat (the regulator of the water companies) in
order for this scheme to be delivered. There are issues with
regard to the adequate capacity of the new sewer in
relation to the frequency of different rainfall events,
the allowance for the expansion of the population, reduction of
permeable land and the impact of climate change. The case to
Ofwat will be supported with information on the
number of people and properties benefiting from the alleviation
scheme. If the case is successful, planning applications for
the works will be submitted to the Royal Borough and the
borough of Hammersmith & Fulham.
Reduce the flow of water into sewers during periods of
heavy rainfall.
This can be achieved through the provision of
Sustainable Urban Drainage Systems (SUDs) both in new developments
and through retroffiting that which exits. The Council is working
in partnership with Thames Water on two SUDs projects:
- SUDs in small developments: the outcome of
this project will be a tool used by developers and planning
officers to ensure provision of SUDs in all development and not
just in major developments. This project will be finalised by the
end of this year and we aim to start using the tool at the
beginning of 2012.
- Retrofitting SUDs in
existing properties: the Council is helping Thames Water with their
pilot project to retrofit SUDs so that a cost-effective and
sensitive approach can be developed.
There are a number of major developments in the lower
catchment area of Counters Creek sewer that are under construction,
have been built recently or are in the planning stage. These
include: Westfield, the Warwick Road sites; Earls Court/West
Kensington Opportunity Area, White City and the Westfield
extension. These developments have the potential to increase the
amount of foul water entering the system but they should be
seen as opportunities to reduce the amount of surface water
discharging into the system compared with the existing situation.
Lessons can be learnt from some of these developments (e.g.
Westfield in the borough of Hammersmith & Fulham). It is
also important that residents' views are taken into account when
the decision is taken at the planning application stage.
Mitigating against the increase in impermeable
land
The mitigation of the impact of small
developments are key to reduce the flooding risk in the borough as
they are responsible for the constant increase in impermeable
surfaces. The Council has specific policies to stop paving front
gardes where planning control exist. However, the Council is
also working on a tool to include SUDs in small developments
(as explained above). This tool will be used from February 2012. It
is important to note that the planning system cannot control the
paving of back gardens as this is permitted development and is
therefore exempt from planning control.
The Council is working in partnership with other
London boroughs who are higher in the Counters Creek catchment
area (Brent and Camden) through the Drain London Forum. Development
in these boroughs could have an impact on the amount of water
in the sewer system that flows into the Royal Borough so it is
important that they also embrace SUDs.
Public meetings on flooding
Every six months Thames Water organises public
meetings in the Town Hall to give an update on the Counters Creek
Sewer Alleviation scheme and the installation of Fooding Local
Improvements Projects (FLIPs) in the borough. The last meeting
took place in November 2011. Representatives from Planning and
Borough Development have also participated in these meetings
to update residents on what the Council is doing in terms of
flooding and its new duties as a Lead Local Flood Authority (see
below).
New Duties
The Flood
and Water Management Act 2010 and Flood Risk
Regulations 2009 designated the Unitary and County Councils as
Lead Local Flood Authorities. As such, the Royal Borough, has now
taken over this role. You can read more about our new duties in the
Lead Local Flood Authority webpage.
Page updated 18 January 2012