The cycling charity delivering Sustainable Drainage interventions?

Patrick Williams, Project Leader for the Sustrans SuDS project, explains how and why community street design can make an impact on our travel behaviour, manage flood risks and make our streets better places to live….

Embleton Road SuDS Project

What, you may ask, are a charity who are best known for their work to promote cycling, doing delivering a street design project, focusing on Sustainable Drainage Systems (SuDS)?

In fact, Sustrans have been delivering community street design projects for several years now. Streets are the network that we use everyday, and it’s those shorter everyday journeys where we have the biggest potential to make an impact on our travel behaviour.

Modern living means that we often live apart from our friends and family in a sort of urban solitude. The greater the tendency to be disconnected from the world around us, the more we distrust strangers, and the more we opt to hermetically seal ourselves away in our homes and cars.

Streets become roads, predominantly designed to accommodate greater numbers of cars, and facilitate their efficient movement. Space for people is limited, and segregated – more space for cars, less for people. Mistrustful of strangers, concerned about the dangers of collision with fast moving motor vehicle, we take ourselves and our children from house, to car, to school/office/shop, back to car, and back to house. And so the cycle (no pun intended) continues – we build bigger, faster roads, to accommodate ever increasing numbers of cars – thus reinforcing the physical and psychological barriers to us using the street in more enjoyable and healthier ways.

In our community street design programme, we engage local people, and demonstrate through on-street events and activities that streets are a stage for people to come together. A place to play, a place to walk, a place just to be – a place which belongs to them.

It takes time, we build consensus, we trial new layouts in the street using turf and slowly but surely work towards a re-imaging of the street – in a way which reflects the hopes and aspirations of the local people. It doesn’t have to be expensive, as any party-goer knows, it’s the people that create the vibe.

We believe if people have been part of the creative process they will not only ‘own’ the design but actually use the street in new and wonderful ways.

Why pick Southmead, and what’s the point in SuDS?

Recent years have seen a succession of extreme weather events, with the South West being hit particularly badly with the floods of 2013/14. With the prospect of more of the same, we have to make our ageing drainage systems more resilient, and fit for future purpose.

The Bristol Surface Water Management Plan identified Southmead as an area with surface water flooding problems. The area also suffers from poor water quality; the Southmead River Trym (the destination of most surface water flows in Southmead), forms part of a classified ‘failing’ water body under the Water Framework Directive – In short, Southmead is at risk of flooding, the Trym is polluted, and unless we take action, it’s going to get worse.

So what are Sustainable Drainage Systems, and how do they work?

Sustainable Drainage Systems (SuDS) are features that help to manage flood risk and water quality, as well as providing other benefits that create great places to live.

In natural environments, rain falls on permeable surfaces and soaks into the ground; a process called infiltration. In urban areas, surfaces are often sealed, limiting the ability for rain water to soak away naturally. Instead, water is directed into gulleys, and from these, into a drainage network consisting of pipes and culverts hidden under our streets. The water then eventually finds its way into local watercourses – such as the Trym.

The capacity of existing drainage systems is limited, and often during extreme rain fall, the system just can’t cope. Large amounts of water is discharged into local water courses, resulting in flooding downstream, and when the system can’t hold any more, drains overflow, and streets and houses flood.

Pollution, typically oil residue from cars, is washed down the drain, resulting in the deterioration of rivers. This is particularly an issue, when combined sewers (which collect surface water runoff and foul waste from our sinks and toilets) are overwhelmed by surface water during heavy rainfall.

SuDS don’t have to be complicated

Although SuDS come in various flavours, and can be quite complex, often the principle is actually very simple. Creating a bigger area to capture the rain, and let it infiltrate naturally, gives the water somewhere to go as it lands on the street. Once collected, and held in these systems, the rush of heavy rain water is slowed down, and water is released into the sewer at a reduced rate – this is called attenuation.  And there’s more – As well as slowly releasing water into the sewerage system, as the water passes through the permeable SuDS materials, many of the pollutants held within the water, are naturally filtered out – this is called filtration. The result is sewers that are not overwhelmed, less pollution to local water courses, and lower risks of flooding all round.

It gets even better – Planting in these systems can provide flowers to attract pollinating insects such as bees, and berries for birds. SuDS make streets more attractive, can provide spaces for people to socialise, and when placed on the road, can encourage slower, more courteous driving, helping to make streets more vibrant, and safer places to be.

Two popular forms of SuDS that will be used in the Embleton Road SuDS Project are:

• Rain Gardens

Small planted areas, normally built on roads. By capturing and treating the first part of a heavy rainfall event, a large fraction of pollutants collected from the street will be reduced, improving the quality of water as it enters local rivers.

• Swales

Like a rain garden, a swale is an absorbent, often planted area. A swale is larger than a rain garden, and is normally found in existing green areas such as parks and large verges. Because they are larger, swales capture more water than rain gardens, holding back excess water produced by heavy rain.

First steps towards the Embleton Road experience

As a pilot project, Southmeads flood risk problems will not be solved entirely by Embleton Road SuDS. The project aims to develop and test an approach to retro fit delivery of SuDS, that could be used then as a broader approach across the whole of the city.

Initial feasibility studies were carried our considering the most suitable areas to benefit from potential SuDS, whilst also considering  how these might provide opportunities engage with the community.

Key delivery milestones were agreed, ensuring that the SuDS could be fitted into the council 2015/16 capital works programme, meaning they would be built this financial year. A key milestone relating to this, was that outline designs for the SuDS, needed to be submitted to the council by late July.

Little Meads Primary School and Embleton Road residents.

Among the various locations highlighted, Embleton Road, with Little Meads Primary School, offered a clear opportunity, not only to provide improvements to flood risk and water quality in Southmead, but the presence of the school, gave the potential to engage with the school and public, and by doing so, leave a lasting educational resource.

The school were eager that their eco-council would work closely with us. A number of workshops were then set up throughout June, to consider in more detail, the various elements of the project. The eco-council would then feed back to the rest of the school, as well as parents and teachers, and this would then lead onto an on-street community design workshop.

Residents along Embleton Road where brought into the discussion, and a date for an on-street design workshop was agreed for early July.

Workshop I

SuDS – What they are, how they work, and the benefits.

The children built a standard drainage system with a water bottle, and a drainage tube. Pouring a bucket of water into this demonstrated how the limited capacity meant that during heavy rainfall, flooding can occur. It also demonstrated how contaminants from the road can pollute local rivers, such as the Trym.

To demonstrate how SuDS reduce flooding and improve the quality of the water, the children built a second system using a large planter, a sponge, and some potting compost. The bigger system held more water, and the earth meant that the water was released more slowly into the system, meaning less flooding. The earth and the sponge also helped to filter pollutants washed into the system from the road, so the water entering rivers, such as the Trym, will be less polluted. Some key lessons learned were the principles of infiltration, attenuation, and filtration.

Workshop II

Urban Design – How to create safer, more vibrant streets for all.

We considered how changing the behaviour of car drivers around schools and in residential areas, would make it safer for other users of the road. We looked at traffic data for Embleton Road, and saw that cars still drive quickly along a 20mph road next to a school. We then considered physical methods of reducing car speeds, and how by changing the appearance of the road, drivers will slow down for psychological reasons. Creating an awareness that the road is next to a school, might be a good psychological traffic calming measure. Adding the school’s leaf motif onto the road, might not only tell people thy are next to a school, but make the road look brighter and more vibrant.

Workshop III

Design a better Embleton Road, incorporating SuDS

Firstly a site analysis was carried out. The children’s walked along Embleton Road, considering the various constraints and opportunities offered. These included the position of existing gulleys, and the way that the street is currently used. We then went back into the classroom and, with the help of some large plans, and rather a lot of modelling clay, planned a vision for Embleton Road that would encourage safer driving, people to walk to school, and a pleasant street – It might have also included one or two trampolines!

Following the completion of the school workshops, flyers advertising the on-street design workshop, were delivered to houses along neighbouring streets, and distributed to parents at the school. The workshops were again discussed with residents, and posters were put up advertising the event.

On-street community design workshop

The workshop was held on Saturday 4^th July, from 10am to 12 noon. A section of the road was closed for the morning, with various activities organised along the road. Anyone could attend.

A plan of the street at 1:50 scale was laid out on a series of tables. A number of information and inspiration boards were pinned up next to the plans, and a myriad of items to help create designs, such as plasticine, pens, mini plants, model people and benches were provided.

Staff from Sustrans, the council, and Arup, were on hand to provide help and answer any questions that anyone might have. A loose plan highlighting some of the ideas from the school workshop was provided, as well as a plan with some suggestions from Arup.

All of the residents were supportive of the scheme, and enthusiastic that suggestions developed through the work with the school, were incorporated into the design.

Although no definitive design had been created through the school workshops, there were 3 clear themes:

• Road safety – Students were eager that cars are encouraged to drive responsibly, and courteously along the road

• Identity – As well as being proud of their school, students also felt that by introducing the identity of the school into the finished design, not only could the appearance of the street be improved, but drivers would be further encouraged to drive safely.

• Enjoyable – The appearance of the street could be improved. This would happen partly with the addition of the new planted areas, but also other elements might help improve the general appearance. Perhaps, using brightly coloured leaves (the school emblem) along the road, not only would increase the awareness of the school, but also make the experience of walking along the road more pleasant.

Trials using turf

Using rolls of turf, a number of rain gardens, and planted with flowers. Residents were able to change the form of the rain gardens, and see what the impact of building rain gardens along the road, might have on the appearance of the street. One of the rain gardens took a more rectilinear form, whilst the other, more organic.

Stencils of the schools leaf symbol were provided, and a design using the leaf was created on the road, using chalk.

Lastly, photographs of plants were provided, along with any benefits they may have – bird friendly berries, or flowers to attract bees. Everyone was given the opportunity to vote for their favourites.

All in all, it was a thoroughly enjoyable morning of using the street to meet people, chat and play.

Next steps

Designs and ideas discussed during these workshops are now in the process of being drawn up into plans and 3d visuals. Once these outline designs, showing the location, size, and form of the rain gardens, as well as the swale in the play area, are complete, they will be taken back to residents, and the school, to confirm that everybody is happy with the drawings so far. These will then be developed by Arup, and submitted to the council to be incorporated into the capital works programme, for building.

These drawings will determine the position of the SuDS, but there is still work to do, to develop other measures that could be incorporated – school leaves perhaps. We have already agreed to continue our work with the school next term, and an on going programme of events is in the process of being developed to continue working with the school and residents.

More detail about the progress of the project, and how people can get involved, will be put on the website as things develop.

The SuDS are currently planned to be constructed during early 2016.

To learn more about Southmead Embleton Road SuDS Project or Community Street Design, contact Patrick Williams