DBFL has introduced a transformative shift in our approach to drainage design in response to the climate crisis and our commitment to sustainable engineering solutions. We are leaders in the design of nature-based drainage solutions at regional and site level to mitigate the effects of extreme weather events. Our design approach focuses on replicating the natural drainage regime while ensuring robust and maintainable systems for our clients and future generations. This approach ensures the functional requirements of on-site drainage systems are achieved while also respecting the flood protection of downstream assets and receptors.
We implement Nature-Based Drainage Solutions throughout the built environment. Attenuation ponds, swales and wetlands are designed within residential and commercial development through detailed coordination with the landscape proposals while green and blue roofs are proposed on more condensed high-density development. Our active travel and street projects give a unique opportunity to retrofit nature-based drainage to the existing built environment by introducing rain gardens, swales and tree pits to existing streets where sustainable drainage had not been previously considered. A significant net gain in terms of biodiversity and surface water management can be achieved where nature-based drainage is retrofitted to the existing built environment.
The benefits of Nature-Based drainage solutions can be summarised in the following 5 points which align with our commitment to sustainability while working with natural materials where possible.
Nature-Based drainage such as attenuation ponds, wetlands, open water streams and swales provide nature rich habitats for wildlife and ecosystems. Where newly constructed nature-based features are linked with existing eco systems on sites, such as rivers, hedgerows and vegetation, a net benefit for biodiversity can be established. Traditionally, biodiversity would be eradicated in these development sites.
As school students, we learn about the natural hydrologic cycle of evaporation, transpiration, precipitation, run-off, infiltration and percolation. At DBFL our aim is to replicate this process in the built environment by implementing nature-based solutions. Evaporation, infiltration and percolation can be replicated by providing open water in swales, ponds and streams. Transpiration is replicated by diverting surface water into tree pits and rain gardens where plants and tree absorb water.
Surface water generated in the natural greenfield environment, initially infiltrates to the underlying soils and geology before the ground becomes saturated and overland flow occurs to watercourses. This process naturally recharges the groundwater within underlying aquifers. Traditionally in the built environment, hardstanding areas inhibits infiltration. The incorporation of permeable paving, tree pits, swales and open water bodies allows water to infiltrate before entering watercourses and pipe networks therefore replicating the greenfield scenario.
At DBFL, we engineer sustainable futures which include flood resilient homes and businesses. By implementing Nature-Based drainage, we are controlling surface water at source within developments to protect homes and businesses from flood waters in flood events.
Climate change is predicted to result in more extreme weather events which will increases the risk of flooding along coastlines and watercourses. A key measure to mitigate downstream flooding is to control surface water at source (i.e. where rain falls). The implementation of Nature-Based Drainage Solutions within development sites reduces the volume and intensity of surface water leaving the site and mitigates downstream flood risk.