River Thames Scheme
Handing over design to the public –did it make a difference?
24 April 2018
Jenny Marshall-EvansEnvironmental Scientist
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Agenda
• Introduction
• RTS Vision
• Deliberative approach
• Enhancement opportunities
• Design areas influenced
• Engagement shaped the Vision
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• 14.6 km long
• 20-50 m wide
• 150 m3/s
• 2-3m deep
Schematic
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Intro
The River Thames Scheme (Datchet to Teddington) is one of the UKs largest flood risk
management schemes of recent years. It involves construction of a 15km long flood
relief channel through west London. Black & Veatch is leading outline design for the
Environment Agency and partners.
The new flood channel is in 3 sections (red dashed lines).
• Nearly 15km in length and
• Up to 50m wide
• Flow capacity of 150m3/s
• 2-3 m deep, but water level increases by c.1m when channel in operation
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New opportunities for tourism/recreation/sport
Improving access to the river
Improving landscape and habitats
The vision consists of 3 elements:
- Protecting the communities in the area by reducing flood risk
- Securing the economy by keeping businesses and transport running, allowing the
communities to thrive and encouraging investment
It is the last item where our vision goes beyond the “functional” and becomes more
aspirational.
- To enhance the area by providing new opportunities for tourism, recreation and
sport; improving access to the River Thames; and improving the landscape and
surrounding habitats.
In response to this vision, the project team has placed strong focus on the landscape
and environmental design. Of course, the design has to function as a flood scheme, but
to deliver these wider benefits the scheme needed to be ambitious in its aspirations,
and ensure landscape and environment were at the centre and fully integrated into the
design. It was with these aspirations in mind that we sought to engage the public in the
design.
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Deliberative engagement
A deliberative approach was adopted to engage with the wide variety of
stakeholders, including authorities, user groups, conservation bodies and
landowner
The Discussion Groups help stakeholders to work through the complexities of the
channel design. The key objectives are to give participants an opportunity to:
• share their views, knowledge and expertise,
• suggest ideas; and
• explore options about what the channel could look like and how it can be
used; whilst also
• ensuring that it creates benefits for people, livelihoods and nature.
By using this approach, we hoped to maximise the potential for the Project to
deliver mutually acceptable designs that bring multifunctional benefits, attract
partnership and investment funding, and empower community groups,
organisations and businesses to be stewards of the improvements it will deliver.
Incorporated stakeholders in the iterative design process, including consideration
of the potential environmental effects.
- Minimising the projects environmental impact and enhancing the benefits, as
part of the EIA process.
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• Green: natural ground
• Pink: landfill
• Blue: flood embankments
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Channel section 1
We identified an area where we felt there was a better route to that agreed in the
original Strategy, and wanted the discussion group to be a part of the option appraisal
process.
On this drawing, there is a long section of channel through landfill (as shown in the
pink), and our ground investigations showed this to be a particularly nasty site, with
medical waste found. We therefore considered some alternatives.
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6 options
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Influencing the design
Using:
Optional appraisal using multi-criteria evaluation
Feedback from Discussion Groups
Consensus building at final Discussion Group Workshops
Concerns
- potential effect the introduction of River Thames water would have on the lakes
water quality,
- the risk of introducing invasive species and
- the affects the different options would have on recreation in the lake (especially as
the northern lake is currently a commercial fishery and the southern is used by a
sailing club).
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Option 1 selected
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0%
20%
40%
60%
80%
100%
Strategy (n = 22) 1 (n = 27) 2 (n = 25) 3 (n = 24) 4 (n = 26) 5 (n = 26)
Options
Strongly
support
Support
Neutral
Opposed
Actively object
There was strong opposition to the Strategy option through the landfill and also for
options 2 and 3 which had the greatest impact on recreation in the lake. The most
favoured options (or the least opposed) were options 1 and 4.
We later undertook groundwater and water quality modelling to assess the impact on
water quality, and using this were able to demonstrate to Natural England (needed
because the lake is part of the South West London Water Bodies Special Protection
Area) that it was not necessary to isolate the flood water from the River Thames from
the rest of the lakes, so separation embankments were not required.
A consensus was reached.
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• Green: natural ground
• Pink: landfill
• Blue: flood embankments
Building consensus
Second example:
This shows the original strategy alignment - a straight, trapezoidal channel, through
natural ground.
Flood embankment to the north to protect the Chertsey water treatment works.
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Building consensus
The first workshop asked for ideas for enhancements from stakeholders, including areas
of habitat creation, footpaths, viewpoints etc…
Using the stakeholder idea for habitat creation in this area we subsequently developed
our habitats strategy and led us to focus our efforts on specific locations, such as the
channel at Abbey Meads.
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Abbey Meads
0%
20%
40%
60%
80%
100%
Abbey Meads
Strongly support
Support
Neutral
Opposed
Actively object
In consultation with Affinity Water identified the need for a shallow, wider channel in
this area to prevent affecting their groundwater abstraction requirements.
Having developed a habitats concept using the views from the first workshop the
proposed concept was presented to stakeholders at the second workshop.
No one actively objected to design and overall the majority supported it
We were able to build consensus on this section of the channel.
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Abbey Meads
Using the ideas provided from the discussion groups, expertise from the Project Team
and engagement with the water utility company we were able to develop a concept for
this area of the channel that met the needs and aspirations of all stakeholders and
contributed to achieving all elements of the RTS vision.
We have further developed the design, due to the consensus built from the discussion
groups and have created an area of high value habitat enhancements, incorporating the
entire area in to the channel to create a wet meadow that will be partially flooded in
winter and largely dry in summer with rough grazing during the summer months.
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Shaping the Vision
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Third example:
On this drawing there is an existing landfill site – it’s been poorly restored - and has a
degraded landscape. The project, by its nature of excavating a flood channel, generates
an excess of freely available material (approximately 1.5 million cubic meters).
An initial concept for a raised landform was sketched then a more detailed drawing of 2
options presented to the discussion groups:
- option 1 was the development of country park
- Option 2 was a sports and activities recreation center
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Option 1 selected
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Manor Farm
0%
20%
40%
60%
80%
100%
Manor Farm Option 1 Manor Farm Option 2
Pe
rce
nta
ge
of
vo
tes
rece
ive
d
Options
Strongly
supportSupport
Neutral
The Discussion Group Workshop preferred the concept proposals for option 1.
Stakeholders had several concerns with option 2, with 47% expressing concerns and only
6% expressing support for the ‘Active Leisure & Development’ concept. Option 1 was
subsequently taken forwards as the chosen configuration for the LEA. In certain
instances, specific comments from the Discussion Group Workshop were carried over
into the LEA design such as “Planting of trees along M3 motorway to improve air
quality.”
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Manor Farm Artist’s Impression
“Great, exactly the type of landscape opportunity we
would like out of the scheme ”
Not only did feedback from the Discussion Groups factor into the decisions for the
locations of the LEAs, but attendees also had the opportunity to comment on specific
aspects of the concept plans. Across the sites, there was general support expressed for
the ‘beacons’ concept, additional access routes and the general landscape
enhancements, all of which have been included in the outline design.
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Beacon concept
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Beacon concept:
Provide visual connectivity between the different channel sections – with views between
4 Beacons along the flood channel, but also to other landmarks in the area
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Human/natural benefits
106 ha country parks
4 km navigable channel
4 km navigable channel
183 ha habitat183 ha habitat
23 km footpaths/ cycle ways
23 km footpaths/ cycle ways
- The scheme will deliver a 106 ha of new publicly accessible country parks, with car
parking and visitor facilities (this is equates to roughly three quarters the size of Hyde
Park)
- It will create 183 ha of habitat, with this figure increasing to 250 ha on completion.
- 23 km of new footpaths and cycle ways linking into the existing networks; and
- 4km of new navigable channel
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Summary
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Deliberative approach:
• Two-way dialogue
• Local knowledge and expertise
• Collaborative design
Through a series of meetings, stakeholders suggested 100’s of enhancement
opportunities that were captured in the design of the channel and surrounding
landscape. It will summarise how: a) design suggestions from stakeholders were
incorporated and shaped a vision that linked the history of the River Thames with the
functionality of the scheme; b) consultees were able to influence areas of uncertainty.
Specific examples will be shown of design areas that were influenced by engagement.
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Black & Veatch Ltd., 60 High Street, Redhill, RH1 1SH
+44 1737 856480
24th April 2018
Jenny Marshall-Evans
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