Adam Cane of ACO Water Management explores how housebuilders and developers can build better places to live through including biodiversity and SuDS.
It may come as little surprise, but the current prognosis for biodiversity in the UK is stark. Almost half of Britain’s natural biodiversity has disappeared over the centuries since the Industrial Revolution. Many species and habitats are still being lost today, owing to the pressure to continue building and an ever-decreasing availability of land.
To illustrate the situation, we just need to look at the hedgehog population. Up to three quarters of all of Britain’s rural hedgehogs have been lost in the past 20 years. Already classed as vulnerable to extinction, countryside populations have declined by an average of 8.3% a year for the past two decades, as road networks have left the animals isolated.
In another instance, the UK has seen a 90% depletion in wetland habitats in the last 100 years. As a result, over 10% of freshwater and wetland species are now at risk of extinction, as reported in the 2021 River Basin Management Plan. Only 16% of England’s water bodies are rated at ‘good ecological status’ (GES), which could explain this decline.
These issues are not just having an effect on wildlife. People and places are being negatively impacted, too – replacing green spaces with hard landscaped developments not only means a loss in natural beauty but also increases the chance of flooding. Therefore, it’s no longer a case of just reducing carbon emissions – reversing the impact of the built environment on the natural world is imperative. Here, housebuilders have a unique role to play, and are positioned to make a difference.
PREVENTING POLLUTION
One such way of making a positive change is preventing contaminants left on roads from being washed into waterways and surrounding the surrounding habitats. Controlling the quality of runoff is critical here, forming a key pillar of sustainable drainage systems (SuDS). Natural resources can only clean water to a certain point, so before water is discharged into swales and ditches in SuDS schemes, there needs to be a system in place to treat it beforehand.
Housebuilders, working in conjunction with highways engineers and water management specialists, can use the simple index approach (SIA) to help determine whether the proposed SuDS provide adequate mitigation against pollution hazards like tyre rubber, oils and heavy metals from vehicles.
Developers should also look to combine nature-based solutions and SuDS in both retrofit and new construction projects. Trees and green areas, for example, offer shade, amenity, natural air conditioning and refuge opportunities for wildlife. SuDS solutions, such as bioretention areas, rain gardens, swales and tree pits, take runoff from hard surfacing. This can then make developments more amenable, beautifying spaces for people, making them more aesthetically pleasing and enjoyable to live, work and play in.
BUILDING UP BIODIVERSITY
Continuing in this vein, not only should water be cleansed, but the local ecology should be assessed prior to any construction work, and then continually monitored to ensure that the development does not negatively impact on wildlife. This is a key requirement under the Biodiversity Net Gain regulation, and housebuilders will need to prove that their sites will provide a 10% uplift in biodiversity. Alongside this, habitat guidance in CIRIA’s SuDS Manual states that any new SuDS scheme should link with other local and/or regional habitats to help build and enhance habitat connectivity.
There are several ways to integrate wildlife mitigation measures across developments and roads connecting to these places, from wildlife kerbs and guide tunnels to escape ladders that can help mammals and amphibians navigate road networks safely.
One instance of good biodiversity management that ACO Water Management was involved in is a new 550m carriageway in Wokingham that connects a new housing estate to the wider road network. The project saw a 4.5 hectare open space landscaped to include both nature-based solutions and specially designed SuDS features that protect and improve the diversity of local wildlife.
The ambitious project involved the creation of an ‘eco pond’ and grass verges, which are designed to attract crested newts, dragonflies, damselflies and grass snakes, as well as otters and a variety of birds. Alongside the nature-based solutions, tunnels and guide walls were installed to ensure wildlife can cross under the road. Bringing these features together has harmonised people, wildlife and infrastructure together to co-exist
and flourish.
Creating better places for people and nature to thrive will certainly take a lot of thought and consideration. Housebuilders can begin to turn the tide on habitat loss, and good design is at the heart of driving change.
Adam Cane is sustainability lead at ACO Water Management