Following details of the government’s Environmental Bill last month, Jon Stewart, Business Development Director for Drainage at Polypipe Civils & Green Urbanisation, unpacks the policy for developers and explains why, if considered holistically and creatively, it can lead to better, more marketable homes.
Achieving planning requirements and upgrading or adding to sewer networks during the construction of a new development can be complex. So as specifics of the government’s Environmental Bill were released in early May, many developers looked on keenly to understand what the legislation might mean for future works.
The Bill, which is currently in the House of Lords, will bring unprecedented reform to our foremost environmental priorities, with legally binding changes spanning aspects from air quality and biodiversity, to the regulation of chemicals.
Water, as the lifeblood of the natural world, forms a vital part of the Bill with a focus on how we manage water and wastewater services more effectively for future generations.
In particular, water companies will be required to publish a water resources management plan, as well as a drought plan and a drainage and sewerage management plan. In recognition of the growing pressure on combined sewers as a result of population growth, increased urban density and the challenges we face as a direct result of climate change such as increased rainfall and severe flooding, the Bill focuses on building capacity into the water undertaker’s drainage and sewerage system to meet current and future demand and requires reporting on storm overflow performance annually.
For housebuilders, this means that in the coming months and years, there will be increased pressure from water companies and planning authorities to reduce stormwater discharge when designing and building developments. While seemingly just a further challenge to achieving planning consent, this new requirement – if considered in a creative and holistic way – could in fact make better developments for buyers and address other aspects of the upcoming Environmental Bill.
One such aspect is Biodiversity Net Gain. Once the Bill comes law, housebuilders will need to achieve a minimum of 10 per cent improvement in biodiversity on or near a new build site to get planning consent.
These changes mean developers must now re-evaluate how to introduce green infrastructure to ensure that residential developments comply with sustainable drainage best practice and deliver an uplift in biodiversity post-completion.
To realistically achieve these aims, surface water management solutions must be placed at the heart of dense and diverse green infrastructure while preserving the economic viability of a project.
The next generation
While conventional sustainable drainage systems (SuDS), such as retention ponds, basins and swales, provide a route to manage excess run-off rainwater brought about by extreme weather, they often take up significant amounts of developable space and limit the aesthetic and landscaping options.
Fortunately, breakthrough stormwater attenuation and re-use technologies are giving rise to a new generation of enhanced SuDS that deliver the best of all words. As well as significantly reducing, or even eliminating, the volume of stormwater that enters the combined sewerage network, these innovative green urbanisation systems retain and reuse stormwater to support greater biodiversity above.
Shallow invert geocellular sub-base replacement systems are specifically designed to manage surface water at source. Cells are inter-connected using unique geometric ties to create a uniform structural ‘raft’ with exceptionally high load bearing characteristics.
Such systems can be used to attenuate and manage water at ground, as well as roof or podium level, and a shallow invert makes them ideal for projects where there is a high water table, contaminated brownfield land or where there is a shallow outfall – a situation where conventional deep buried surface water storage tanks would require additional pumping.
Having the ability to store water safely immediately beneath a finished surface allows these systems to be used for irrigation. Surface planting can be sustained by drawing stored water from the raft through special ‘wicking cones’ to the soil above. This unique, net zero feature enhances resilience – supporting volume planting and ecosystems through extended dry spells – and in turn, creates attractive, marketable landscapes while maximising land.
Reset not offset
While a recent revision to the Environmental Bill means that developers can include biodiversity enhancements near to a development, rather than on the site itself, housebuilders – for the good of future residents, our climate and wildlife – should only consider this option as the last resort.
As the pandemic has shown us, green spaces are powerful for our mental health and wellbeing, and similarly in nature, wildlife cannot flourish if isolated to a single place.
To tackle the effects of climate change and create sustainable habitats for wildlife – as well as places buyers want to live – housebuilders should be prepared to think differently and consider new, creative ways of using excess water for positive effect, rather than viewing it as a negative to be controlled.
Innovative green urbanisation solutions make it possible to tackle excess stormwater and achieve biodiversity uplift simultaneously, all the while producing attractive, saleable developments that benefit future owners long-term. All that’s required is a new way of thinking.