Council protects Redbridge school against future flooding with large-scale flood defence scheme

One of the borough’s largest flood defence schemes has been installed at Caterham High School in Clayhall which has previously been impacted by flash flooding.

Caterham High School, in Caterham Avenue, was green lighted for the programme of works and Redbridge Council successfully bid for grants from Thames Water, and the Department for Education.

The completed works saw a range of above ground and underground sustainable drainage schemes (SuDS) implemented at the school to help protect it from flooding, following major damage that occurred to parts of the school in a previous flash flooding incident.

SuDS reduce the risk of flooding by mimicking natural drainage processes to slow the flow of surface water entering sewers and drains – helping to prevent them from becoming overwhelmed and flooded during heavy rainfall.

Overwhelmed sewers and drains were one of the main causes for recent flooding incidents in the borough.

Four SuDS were installed at the school in collaboration with Kenson Highways and SANDS, who designed the schemes:

Attenuation tank

The attenuation tank – a large water storage unit - was built under the school playground. Connected to the school’s drainage system, it can hold large amounts water during heavy rainfall, helping ease the flow of water going into local sewer systems.

Water butts

Four large 1000 litre water butts were installed on the school site to capture and store rainwater. The water collected is used for gardening and other outdoor purposes at the school.

A rain garden

Rain gardens are natural water drainage systems designed to look like a mini garden, featuring plants, shrubs, and other greenery. The rain garden at the school captures and absorb rainwater to drain it away slowly.

Adapted planters

The specially adapted planters feature an internal reservoir with a slow-release drainage system to ensure heavy rainfall does not overwhelm the school site or local sewer system.

The flower and herb filled planters, and rain garden, also have the added eco-benefit of boosting biodiversity and helping cultivate new wildlife habitats around the school.

Following completion of the project an interactive workshop was held at the school to foster a greater understanding of flood resilience and the importance of environmental stewardship among students. The student centred event included educational activities about flood management and planting sessions as part of the school’s new green infrastructure, and was delivered in collaboration with project partners Kenson Highways who installed the SuDS, and SANDS, who designed it.

Headteacher of Caterham High School, Belinda Chapple, said: “Our wonderful school was badly impacted by a flash flood, but with our new flood defences and drainage systems we feel confident that our school is resilient against further significant damage. We can plan for the future with real confidence.

“We also now have water butts, planters and a rain garden with many different varieties of plants that attract insects and birds. It's a joy to see the flowers blossoming and adding colour and greenery to the site. Some planters are specifically for herbs which fosters lots of interesting conversations about the delights of home cooking between children and staff. “These biodiverse additions make our school more attractive and greener, especially around the central playground pond area. The children had a lovely time being involved in the planting. It's made the playground a much more attractive place.”

Combined, the flood defence measures put in place at Caterham High School, can store and divert approximately 175,000 litres of rainwater away from the local sewer systems to help prevent flooding. That’s the same volume of water that would be produced if you used a garden hose continuously for nearly seven days.

Cabinet Member for Environment and Sustainability Cllr Jo Blackman said: “Redbridge is seeing the effects of climate change with more frequent bouts of flooding from torrential rain. To help reduce the impact of flash floods in our local communities and schools we are investing in a wide range of flood alleviation measures including the use of SuDS to help reduce flood risks in the most impacted parts of the borough. It was great to visit this scheme at Caterham which includes planters and rain gardens as a natural way to support the local drainage infrastructure and encourage biodiversity in the borough.”

Thirteen new flood alleviation schemes are set to go ahead in Redbridge. It will see flood risk reduction works being ramped up in several areas that have previously been prone to flooding, including Fullwell, Fairlop, Mayfield, Monkhams and Wanstead Village. The move to build Redbridge’s resilience to flooding comes as the risk of flash floods occurring more frequently increases because of climate change. Over the next ten years the Council will be investing just over £11m into schemes that help reduce local flood risks to protect local homes and businesses from flooding.

For information on staying flood aware, go to the council’s flooding web page on:  https://www.redbridge.gov.uk/flooding