SuDS - Sustainable drainage systems

What is SuDS?

a relatively new approach to managing rainfall by using natural processes in the landscape to reduce flooding, control flooding and provide amenity for the community.

General benefits to SuDs:

easy management

environmentally friendly

requires little to no energy to function

sometimes enhances biodiversity - depends on SuDs.

General limitations to SuDs:

small scale

only benefits localised areas

relatively new (UK legal requirement after Flood and Water Management act in 2010) → difficult to measure

Swales:

linear depressions, usually covered in grass, which slowly transport water away

designed to promote infiltration where soil +groundwater conditions allow, with water colllected in vegetation also needed,

Infiltration trench:

a long, narrow trench lined with filter fabric or backfilled with stone/or other things.

What do SuDS use?

rather than using environmentally unsustainable techniques or construction, uses techniques that recreate natural drainage systems

means water is allowed to flow gradually through system before being removed

Examples of SuDS:

introducing permeable surfaces, like grass verges

green roofs which increase transpiration

Swales

Ponds

What was the original aim of the Lamb Drove SUDS scheme?

to demonstrate that SUDS are a viable and attractive alternative to more traditional forms of drainage and to deliver practical solutions

what measures have been implemented in the Lamb Drove SUDS scheme?

-green roofs
-detention basin
-filter strip
-swales
-water butt
-permeable paving
-retention pond

summarise the impacts of the Lamb Drove SUDS development

-cost-effective
-construction and ongoing maintenance costs have been 10%
-substantial improvement in the biodiversity, ecology and subsequent quality of life
-visually enhanced and attractive landscape
-increased amenity and social value to both residents and the local community
-improved quality of water

summarise evidence that demonstrates that the Lamb Drove project is a success and cited as 'best practise' for all planners nationally

-less heavy metal concentrations at Lamb Drove
-half of copper levels at a nearby control site
-1/6 of zinc levels at a ncs
-1/12 of lead levels at a ncs
-1/2 of chromium levels at a ncs

successes of the Lamb Drove SUDS scheme

-Successfully intergraded a comprehensive SuDS scheme within a residential environment, with positive reactions from both the residents and stakeholders.
-Substantial improvement in the biodiversity, ecology and subsequent quality of life at Lamb Drove compared to typical residential developments.
-The sculptured swales and detention basins have resulted in a visually enhanced and attractive landscape. This provides increased amenity and social value to residents and the local community.
-The use of SuDS has resulted in an improved quality of water leaving the site compared with traditional piped drainage systems.

challenges experienced in the SUDs system

• Input of specialist SuDS drainage expertise was effective from the FLOWS team but there needs to be wider understanding and expertise amongst other stakeholders.

• Need to keep SuDS simple, as this will reduce maintenance costs and the likelihood of system being well maintained into the future. Also a key advantage of swales and other surface-based SuDS is that problems can be observed and dealt with as they arise.

Why are SuDs needed in London?

-manage rainfall
-replace impermeable surfaces with sustainable drainage systems
-improve water quality
-manage flood risk
-reduce surface water

why does the river Lea in London cause flood risk issues?

because the channel morphology encouraged flow conveyance and pushes issues downstream to areas where the water could get out of the bank

how has the river lea been reprofiled to reduce risk of floods?

-contaminated land was treated

new river bank profiles were excavated and

an agreed landscape and planting strategy
-banks lowered and reconnected the channel with its flood plain
-areas of land lowered to create floodplains
-vegetation cleared to open up river for public

organisations involved in river lea scheme

environment agency, thames water, groundwork lution, luton friends of the earth

benefits of river lea sud scheme

-new bank profiles have created a new flood storage facility for 1 in 50 year flood events
-water conveynance has also been improved by reducing how quickly water flow passes through the system
-new bankside habitat has been created
-reassure locals there is a lower risk of flooding

What regeneration was heavily tied into River Lea’s SUDS scheme?

The Olympic Park regeneration