Adam Cane, Sustainability Lead at ACO Water Management, looks at how we can build better by boosting biodiversity
Biodiversity depletion in the UK may not come as a shock. Since the Industrial Revolution, Britain has lost over half of its natural biodiversity. There is still a need to build more infrastructure as human populations continue to grow which, in some cases, has a negative impact on nature where construction leads to land loss, fragmentation and degradation.
This is pushing many species and ecosystems into decline and some to the brink of extinction.
To understand the vulnerability of species, we need not look any further than the humble hedgehog. According to the National Biodiversity Network (NBN), in the past 20 years, up to 75% of Britain’s rural hedgehog populations have disappeared and are considered vulnerable to extinction with road networks, urbanisation and fragmentation considered major factors.
According to the 2021 River Basin Management Plan more than 10% of freshwater and wetland species are currently in danger of going extinct. This is linked to the decline in wetland ecosystems which have decreased 90% during the past 100 years in the UK. A likely culprit for the decline could be the fact that just 16% of England’s water bodies are in a good ecological state (GES) due, not only to water discharged by water companies, but also oil, hydrocarbons, metals and plastics discharged to the natural environment from the connected road network and separated surface water systems. Pollution of this sort has a massive negative effect on nature and people and has not yet been properly quantified.
Changing a landscape from its natural state and replacing it with hard-landscaping can also increase the likelihood of floods, potentially having a severe impact on people, infrastructure and nature. As a result, reversing the influence the built environment has on the natural world, mimicking natural systems and supporting nature-based solutions (NBS) is now more important than ever. The industry must balance the need to reduce carbon emissions with a duty to protect and enhance the natural world. Housebuilders are able to play a special role in changing things for the better and providing better outcomes for homeowners and broader society.
Footprint only construction
For the above to work, the natural environment needs to be left as intact as possible. Leaving soil undisturbed is best for nature but necessary for building. The reality is that soil health has degraded globally, likely due to frequent building works. Disturbing soil releases a significant amount of naturally stored carbon into the air and disrupts the normal activity and lifecycles of native plant, bacteria and animal life, all of which play a vital role in fortifying natural biodiversity.
Where disturbing soil is unavoidable, the top 150mm – where the majority of life is – should be kept safely and stored or used elsewhere on site. Any vegetation should be kept in natural areas of the site for biodiversity to find refuge. Developers should also consider temporary fencing wherever possible to protect nature from making unwanted ingress.
Every living organism needs water to survive. Preventing toxins on roads from washing into waterways and neighbouring habitats is one technique that has a positive effect on the environment and regulating the quality of runoff is crucial, serving as a fundamental rule of sustainable drainage systems (SuDS). Water treatment systems like ACO’s V-Septor (Hydrodynamic Separator), Q-Ceptor, or QuadraCeptor solutions can be put in place before water is discharged into swales and ditches in SuDS schemes. These are vital additions because natural resources can only purify water so far and should be allowed to function and grow as nature intended.
The V-Septor, for example, is designed to capture sediment bound contaminants and floatables by directing incoming stormwater to make a vortex, slowing the water so the suspended solids settle down in the sludge chamber. Baffles work as barriers to keep sludge and suspended plastics in the chambers rather than flowing back out during periods of heavy rain. Once cleaned, water can move through an outlet back into the environment. Remaining debris can be easily removed during regular maintenance.
To specify such SuDS systems and understand the impact of different site developments, housebuilders can use the Simple Index Approach (SIA) as set out in the CIRIA SuDS Manual, in collaboration with water management experts and manufacturers. By doing so, housebuilders can assess if a SuDS design offers sufficient protection against pollution dangers such as tyre rubber, lubricants and heavy metals from automobiles etc.
The use of SuDS in both new builds and retrofit projects should be embraced by developers. Runoff from hard surfaces can be captured by SuDS features such as bioretention zones, rain gardens, swales, and tree pits supported by proprietary cleaning products. By making developments more hospitable areas for people to live, work and enjoy recreational activity helps enable positive engagement with the natural environment.
To ensure that we protect key species we must first examine the local ecosystem before beginning any construction work. The Environment Act 2021 makes it clear that new developments in England must demonstrate a minimum 10% Biodiversity Net Gain, making systems like SuDS and the use of Nature Based Solutions (NBS) increasingly necessary. A new SuDS scheme should connect with other local and/or regional habitats to help create and strengthen habitat connectivity, according to recommendations in CIRIA’s SuDS Manual.
Each site is different but there are a range of products on the market, such as wildlife kerbs, guide tunnels, and escape ladders which can help integrate wildlife mitigation measures. These features can aid mammals and amphibians in safely navigating road networks and mitigate entrapment or fatalities. There is also the opportunity to create refuges by integrating bird boxes, bat boxes and bug hotels into houses.
Engagement opportunities can be created, and housing projects can be connected, using the Habitat Matters Mapping System. A free tool that enables the replication of the physical environment, connecting users to the built environment asset using a QR code. The Habitat Matters Mapping System makes it possible to submit biodiversity observations that contribute to national record keeping. Housebuilders have the opportunity to go beyond simply offering products and systems by better connecting people to infrastructure and nature.
Built to succeed
As an industry, we have the knowledge, technologies and tools to build better environments where people and wildlife can flourish. The loss of habitats can start to be reversed through design. ACO possesses a range of expertise and can provide a free consultation, design service or Continued Professional Development (CPD) to help create sustainable drainage.
For further information on ACO visit https://www.aco.co.uk/