• 14 November 2019

Enhancing natural processes with Green Infrastructure

The growth in public awareness of our impact on the natural world has increased a desire to make an active difference before it’s too late. Having reached every corner of society, the development sector has heavily focused on improving its environmental impact in recent years, also promoting the sustainability and ecological benefits achievable with careful scheme design.

By introducing a network of high-quality green spaces and environmental features, projects can have a positive impact on natural processes and nature. We see this increasingly in new schemes where ‘Green Infrastructure’ (GI) design is integrated into the design principles.

It is common for green initiatives such as SuDs (Sustainable Drainage Systems), green roofs and walls to be included within new developments, however there is now a greater emphasis on providing a more holistic approach to the role of GI. This has progressed to the concept of an ‘Urban Greening Factor’ for both residential and commercial builds being addressed in the current Draft London Plan [latest version published in 2019]. This new policy describes the Mayor of London’s strategic approach for GI and how this can be assessed and planned for, assisting boroughs and developers from the beginning of the design process in determining the appropriate delivery of urban greening.

We spoke to Tom Hurlstone, a Principal Landscape Architect within Waterman Infrastructure & Environment, who specialises in environmental enhancement, public realm renewal and protection schemes, as well as supporting any forward-reaching programme which will integrate targets into future planning policy and guidance.

Tom says; “It is likely a standardised approach will emerge to allow the selection of green infrastructure elements that are most appropriate to a given scheme. Early integration will reduce abortive design work, provide commercial certainty of developable areas and robust support through the planning process. This flexible Urban Greening Factor will encourage GI delivery to be adaptable to all site contexts, conditions and land values to meet recommended targets. For the first time, this allows the benefits of engineering and environmental input to be calculated relative to their contribution to green infrastructure.”

Due to the multiplicity of London as a city, policies tackling poor air quality and deficiencies in green space need to be approached borough by borough to enable the unique environments of each borough to be recognised. With the effects of climate change causing unpredictable weather conditions, such as floods due to heavier rainfall, our cities must become more adapt at controlling these eventualities. In recent years, SuDs have become an essential part of our scheme designs as the impact of previously uncontrolled urbanisation became apparent.

Tom explains; “It works by mimicking the natural drainage system and provides a method of surface water drainage, taking account of quality, quantity, amenity and ecological issues. These systems manage runoff from developments, therefore reducing the flood risk and improving water quality by managing pollution. However, the demand for a wider GI approach within residential and commercial schemes requires a higher standard to be introduced to all projects, major and minor, across the country.”

“An urbanised site may place greater reliance on SuDs, green roofs and street trees, whereas a peri-urban site may make greater use of rain gardens, woodland blocks and areas of open water. When accessing the appropriate system for our 187-ha self-building housing scheme at Graven Hill, our flood & drainage team designed a SuDs drainage swale that provided multiple environmental, engineering and economic benefits. In a similar way, retaining existing mature trees with Tree Preservation Orders (TPO) at our Axis Square project in Birmingham allowed us to include boundary trees that will assist with the management of pollution, climate moderation, rainfall attenuation, increase adjacent land values within the proposed design.”

In addition to government schemes to incorporate more green infrastructure into our cities, the European Union adopted a six-target Biodiversity Strategy in May 2011 in a preventative measure to stop biodiversity loss within Europe by 2020. As part of their ongoing aims, Target 2 focuses on establishing GI in existing ecosystems and restoring 15% of those areas which have already been degraded. To assist developers in placing more green infrastructure and achieving a biodiversity net gain in an accountable and structured manner, our ecology specialists in Bristol have developed a Biodiversity Toolkit in conjunction with Berkeley Homes. This includes a detailed project management and Biodiversity Impact Assessment (BIA) calculator, BREEAM pre-assessment summary, ecology survey calendar, species planting lists, and lists of national and local priority habitats and species to allow for effective ecological design.

Tom says; “Despite ever-increasing pressures on budgets and accessibility of open space developments to create the desired sustainable environments, the snowballing effects of green infrastructure has already begun to be appreciated across the UK and is something we are seeing more and more of within the projects we are working on.”

Although the development industry is now starting to incorporate green infrastructure into schemes there is still some way to go in ensuring it is considered at the very forefront of the design process. It will take a concerted effort from everyone involved in the design process to push for the inclusion green infrastructure within new developments. Waterman are very much up for the challenge.

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