Permeable paving & redesigned tenfoots: New schemes to reduce flood risk in Hull

DEVASTATION: Hull under water after the 2007 floods. Picture by the British Geological Survey

By Angus Young

The waterlogged streets of Derringham photographed from the air by the British Geological Survey became the defining image of the devastating flooding experienced in Hull in 2007.

Now the same area which flanks Priory Road in west Hull is about to see the latest in a series of community-based flood alleviation schemes aimed at reducing the risk of a similar event happening again.

The immediate lesson learned from the floods of 16 years ago was that Hull’s combined sewer and storm water drainage system had been unable to cope with prolonged intense rainfall, despite being upgraded at a cost of £200m just six years earlier. In short, the rain and the surface water run-off on that fateful day in late June had nowhere to go.

Slowing that flow of water into the drainage system became the subsequent focus of a number of large-scale construction projects to create several water storage lagoons on the western outskirts of the city.

At the same time, smaller-scale flood alleviation work started on school playing fields, in parks and public greenspace where mini-swales and so-called aquagreens were created to do the same job on a more local level.

PLANNING AHEAD: Strensall Road in west Hull, where an aquagreen is being created. Picture by Living With Water

More recently, the Living With Water partnership has switched its focus from grass to concrete, looking at how actual streets could be similarly re-designed to control rainwater flow.

Established as a direct result of the 2007 floods, the partnership includes Yorkshire Water, Hull City Council, East Riding Council, the Environment Agency and the University of Hull, and the first fruits of its new £23m five-year investment programme were unveiled last month in Rosmead Street in east Hull.

That scheme has seen the old road – including its traditional gullies – ripped up and replaced with permeable paving made of non-porous blocks with spaces between them to allow water to flow through. The rain is then collected underneath with the eventual flow into the sewer controlled to reduce the likelihood of flooding.

Delivered on time and within budget, officials also point to intensive work with the local community as being key to its success including the operation of two temporary car parks during the street’s five-month closure. Now they are hoping for similar results back in Derringham where an open greenspace behind homes in Strensall Road is set to be converted into an aquagreen.

However, unlike work carried out a few years ago on a similar patch of nearby land in Bristol Road famously captured in that iconic aerial photograph, this scheme will also include re-building a private tenfoot between two properties which currently provides access for vehicles to the rear of the houses and the greenspace itself.

GROUNDWORK: Children from Estcourt Primary Academy in Rosmead Street, east Hull, where the old road has been replaced with permeable paving. Picture by Living With Water

City council flood risk manager Rachel Glossop explained: “The idea is to effectively channel surface water from the street down the tenfoot and into the aquagreen where it will be stored for a while before being released. To do that, we need to create that channel by changing the levels in the tenfoot itself.

“There is also an opportunity to create a new grassed parking space with sustainable drainage around the edge of the aquagreen so we are asking residents whether they want that or not.

“Ultimately, it’s important to remember that we’re not saying any of these schemes will completely prevent flooding. However, we do know they will reduce the probability of flooding and, in some circumstances, give people the time they need to prepare, which didn’t really happen at all in 2007.”

With other community-led projects in Bilton currently in the pipeline, the partnership acknowledges its work definitely doesn’t fall into the ‘one size fits all’ bracket. The current crop of projects are also being promoted as template ideas for wider adoption in the future when additional funding is available.

“We can’t re-engineer the whole of the city all at once,” said Rachel “but what we can do is better understand both the threats and opportunities that water brings and increase flood resilience across the region.”