A cutting edge bio-technology system is being tested by Highways England to improve water quality around a Site of Special Scientific Interest (SSSI) in Devon.
Water run-off from the A38 and adjacent farmland can carry pollutants such as oil and metal residue, and this has the potential to impact water quality in the Dean Burn and the surrounding area, including Potters Wood SSSI.
The new system features a bio-engineered filtration pond which will substitute a traditional reed bed by using an engineered soil specifically designed to trap dissolved pollutants in the highways water run-off. This should significantly enhance the quality of water running into Dean Burn and improve the local ecosystem.
The system is being trialled for the first time by Highways England and if successful could be rolled out and used across the country.
Project manager Michelle Reed said:
We are delighted to be able to work on such a worthwhile pilot environmental scheme, especially as it is the first time this system has been used on the strategic road network in England.
The filtration system provides a physical barrier to polluted water, then chemical and biological mechanisms work in combination to break down even more pollutants. It also has the advantage of taking up far less space than other treatment systems, which makes it very cost effective.
When completed, this work should significantly improve the quality of water running into Dean Burn and help to support the local environment and its wildlife.
Bug hotels, butterfly scrapes and bee banks are also being installed as part of the work to benefit biodiversity in the area.
The scheme, which has been designed by Highways England contractor Kier and delivered by South West Highways, will start on Monday 10 June and is expected to continue for 14 weeks.
In order to modify the existing drainage system and divert it into the new treatment system, a tunnel will be bored under the A38, which will limit the impact on traffic.
However, two overnight lane closures will be required on the A38 in August to make the drainage connections. There will also be temporary traffic lights on the B3380 and the road between Dean Burn overbridge and the A38 westbound onslip during June and August.
Highways England is committed to a national Biodiversity Plan which is being supported by a £30 million national investment programme over the next five years. The plan recognises road verges and associated land can be managed to provide areas of habitat, relatively free from human access, that may be scarce in the surrounding landscape. These road verges can also be used to connect fragmented habitats in the wider landscape, enabling plant and animal populations to move and interact, and so become stronger and more resilient.