Grand designs on water

Water sensitive urban design has a big role to play in creating an economical and resilient water infrastructure for the UK, argues Paul Shaffer, associate of the construction industry association, CIRIA

The challenges of delivering effective, efficient and reliable water and wastewater services are well understood. Urbanisation, climate change, environmental protection, expectations from the public and the quest for cost effective infrastructure delivery and operation are some of the potential head aches that trouble the UK water industry.

Water sensitive urban design (WSUD), originally an Australian concept, recognises and attempts to overcome these challenges by integrating water into urban development and planning from the earliest stages to maximise the opportunities for sensitive water cycle management. WSUD can be synonymous with sustainable urban water management and integrated water cycle management, which encourages ‘big-picture’ holistic thinking about the water cycle. This includes managing potable water, surface water, wastewater (sewage and grey water), as well as natural watercourses.

It is this integrated approach and the consideration of water supply and wastewater that differentiates WSUD from how sustainable drainage systems (SUDS) are defined in the UK.

WSUD is a seductively simple concept, but complex in delivery, as it focuses on the relationship and synergies between urban design and development, liveability, ecosystems, landscape, and the urban water cycle. It challenges our traditional approach to water management by recognising that community values and sustainability should inform urban design decisions and water management practices, which should be an integral part of urban planning processes, not simply ‘tagged-on’ at the end.

The objectives of WSUD are to:

  • Protect and enhance natural systems within urban environments
  • Manage the impact of surface water on watercourses
  • Control the generation and treatment of sewage
  • Consider opportunities for daylighting culverts and urban channels
  • Manage water resources and abstractions to maintain groundwater levels and surface water flows
  • Promote and deliver water conservation
  • Reduce the use of potable water
  • Promote the harvesting of rainwater
  • Promote the use of greywater and effluent recycling
  • Integrate surface water management into developments
  • Protect water quality
  • Manage flood risk
  • Improve biodiversity and urban design
  • Protect public health by providing liveable, resilient and adaptable urban developments

The urban water cycle is under increasing social, environmental and economic pressures. Recognising this there are numerous policy and regulatory drivers that relate to climate change, water quality, flood risk management, the natural environment, public health and general sustainability.

The challenges of managing the water cycle are demonstrated by the droughts experienced in parts of the UK in 2006, the subsequent flooding in some of the UK in 2007 and the drought conditions currently affecting many parts of England. WSUD can also help overcome some of the wider challenges being faced by the water industry that include:

  • Reducing carbon and embracing innovation
  • Environmental pressures and regulations
  • Population growth and distribution
  • Effectively managing water networks and assets
  • Delivering multi-functional infrastructure economically
  • Consumer expectations and welfare
  • Ageing infrastructure and traditional approaches to water management

Traditionally we may have designed and built our way out of these challenges with hard engineered sewers and treatment systems. In recent years we have begun to recognise there are more sustainable approaches to respond to these environmental and regulatory pressures In England and Wales the Cave review on competition and innovation has highlighted the potential for change and how the regulatory regime should facilitate inset appointments which could enable the delivery of more WSUD approaches like SUDS, water and effluent reuse and less intensive water treatment for different uses. The Cave review highlights the role that competition in the water industry has in helping the UK mitigate and adapt to the effects of climate change. This can only be achieved if the integration offered under a WSUD approach is pursued and one wonders how further fragmentation by more service providers can achieve this. The requirement for sustainable water management will increase in response to environmental and legislative drivers. WSUD will become crucial in providing an inclusive

approach to spatial planning, urban design and water management, helping to overcome the challenges of delivering more sustainable developments within a changing climate.

Better performance
In the UK we have yet to really deliver WSUD or integrated water management in our housing developments. Building Regulations provide a baseline compliance for water efficiency and some developers are striving for better performance by using the Code for Sustainable Homes and comparable initiatives like BREAAM and LEED for commercial buildings to assess (and improve) environmental performance.

Looking at sustainable drainage; the commencement of Schedule 3 of the Flood & Water Management Act (FWMA) in England and Wales should improve the delivery of SuDS.

There is also growing interest in how far the Water White Paper will promote retrofitting SUDS and WSUD. It is likely that the benefits of the FWMA and the White Paper will not be realised for some time. Despite, this there are developments that have already recognised the opportunities and implemented SUDS (Lamb Drove, Cambridge; Elvetham Heath, Hampshire; Blashfield Place, Lincolnshire).

It is a similar picture with water efficiency, where only a handful of large developments have wholeheartedly adopted water efficiency (Millennium Green, Nottinghamshire; Gallions Ecopark, Thamesmead). While Lamb Drove and the Gallions Ecopark may be exceptions to the rule, the use of rainwater harvesting systems, water efficiency and SUDS are seldom delivered on the same development and very exceptionally do they include innovative wastewater treatment and recycling.

When these technologies are integrated they are often as part of a showcase eco-house or eco-development. Some of these systems are pioneering and therefore more experimental and temperamental than acceptable for mainstream developments.

Water cycle studies (WCSs) may offer a chance to promote WSUD. Around 80 WCSs have been produced in partnership by local Planning Authorities to determine the timing, location and requirement of sustainable water infrastructure and integrate it within the local planning framework. A WCS will tend to flag the requirement for integrated water management, rather than provide guidance on delivery but combining these with development masterplans provides a strong evidence base and framework. This combination is a prerequisite for eco-towns, where the masterplans set a vision to more holistically manage water.

WSUD and its holistic approach to masterplanning, detailed design, delivery and management will be essential in delivering sustainable drainage, water efficiency and water infrastructure to create fantastic places for people to live, work and play while reducing the impacts on the natural and built environment. It is accepted by a growing number of disciplines that WSUD is appropriate and required in the UK. By working in partnership and using more imaginative thinking we should be able to

deliver better water cycle management and water sensitive developments in the UK.

CIRIA, building on its guidance on sustainable water management, has been developing ideas with support from Arup, Aecom and Pennine Water Group to explore the role of WSUD in the UK. CIRIA is fundraising a scoping study and has some interest from the Government, regulators, water companies,

consultancies and manufacturers of water related building products and is looking to work with others to champion water sensitive urban design in the UK.

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