Image description: cars stuck in traffic.Photo by Nabeel Syed on Unsplash
After six years, Brighton’s Wild Park rainscape, formed of a vegetated swale linked to four planted basins, is almost completed.
The Aquifer Project, formed in 2016 to protect the chalk aquifer, secured £1.79m funding from National Highways to build the rainscape with the help of Brighton and Hove city council.
The park drainage system was designed to absorb run-off water pollution from one of Brighton’s busiest roads, breaking it down through a variety of processes involving plants, sunlight and microbes in the soil. Crucially it will prevent it from seeping into the precious chalk aquifer that lies beneath the city, which supplies residents with drinking water.
The little-known risks of road run off
Research by Martin Smith, a professor of geochemistry at the University of Brighton, previously found that contaminant levels in the area’s water were higher than recommended.
The Guardian reported road runoff, the liquid that trickles off roads and into our waterways when it rains, is not monitored by the UK government or globally, and the makeup of this chemical and microplastic cocktail will vary from country to country and from one road to another.
Yet, millions of gallons of this toxic liquid pour into our waterways every year and one study suggests microplastics shed by car tyres could make up a quarter of the microplastics in the environment. Many of the chemicals present are known to be toxic to aquatic life and in 2020 runoff was linked to a vast die-off of silver salmon off the US west coast. A recent study in southern China found tyre-derived chemicals in most human urine samples, suggesting they are transferred through the food chain. This is especially concerning as some of the chemicals are known carcinogens.
Brighton leading the way in tackling road run-off
Monitoring the problem or stopping it at source appears, for now, too complex for many local authorities and governments. Coping with storm water has become a severe challenge for local authorities and governments everywhere as the climate crisis brings heavier rainfall and more rapidly overwhelms city sewage systems.
However, Brighton’s drinking water is sourced from the underground chalk aquifer, meaning preventing pollution from seeping into the ground is crucial to reducing reliance on chemical water. Under the new system, instead of seeping directly into the chalk aquifer, water from the motorway will be captured and will flow along a 1.2-mile route, passing through multiple stages of filtration, before being released into the ground. Two vortex separators have been installed in a balancing pond near the motorway to remove particulates, such as grains and granules. The remaining water will then move through three bays of reeds and planting before being piped to settlement basins in Wild Park.
Increasing access to nature
Wild Park nature reserve is in the Moulsecoomb area, which is highly deprived, and the team behind the development are hopeful the landscape will improve the local community’s access to nature as well. Smith and his students will continue to monitor the performance of the Wild Park rainscape over the coming years – data he hopes to share with other councils to inspire similar developments.